Nowadays there is increasing interest in identifying–and using–metabolites that can be employed as biomarkers for diagnosing, treating and monitoring diseases. Saliva and NMR have been widely used for this purpose as they are fast and inexpensive methods. This case-control study aimed to find biomarkers that could be related to glioblastoma (GBL) and periodontal disease (PD) and studied a possible association between GBL and periodontal status. The participants numbered 130, of whom 10 were diagnosed with GBL and were assigned to the cases group, while the remaining 120 did not present any pathology and were assigned to the control group. On one hand, significantly increased (p < 0.05) metabolites were found in GBL group: leucine, valine, isoleucine, propionate, alanine, acetate, ethanolamine and sucrose. Moreover, a good tendency to separation between the two groups was observed on the scatterplot of the NMR. On the other hand, the distribution of the groups attending to the periodontal status was very similar and we didn´t find any association between GBL and periodontal status . Subsequently, the sample as a whole  was divided into three groups by periodontal status in order to identify biomarkers for PD. Group 1 was composed of periodontally healthy individuals, group 2 had gingivitis or early periodontitis and group 3 had moderate to advanced periodontitis. On comparing periodontal status, a significant increase (p < 0.05) in certain metabolites was observed. These findings along with previous reports suggest that these could be used as biomarkers of a PD: caproate, isocaproate+butyrate, isovalerate, isopropanol+methanol, 4 aminobutyrate, choline, sucrose, sucrose-glucose-lysine, lactate-proline, lactate and proline. The scatter plot showed a good tendency to wards separation between group 1 and 3. NMR spectroscopy analysis provides information on both the structure and the composition of low-molecular-mass metabolites in biological fluids and is a rapid and low-cost technique for exploring pathological metabolic processes. The major advantages of NMR spectroscopy include its unbiased metabolite detection, quantitative nature, and high reproducibility. NMR-based metabolomics could be appropriate as a cost-effective solution for high throughput analysis . Saliva Glioblastoma (GBL) (2016 WHO classification of CNS tumors) is one of the most lethal primary malignant tumors of the central nervous system, as the mean survival is under 15 months and the five-year rate is under 10%. The risk factors for GBL are unknown, although constant exposure to ionizing radiation or chemical agents can increase its development. GBL is mainly diagnosed at advanced ages, with a mean age on diagnosis of 64 years [Chronic periodontitis (CP) is an inflammatory disorder characterized by the progressive and irreversible destruction of the tissues surrounding the tooth. It affects approximately 50% of the adult population and its incidence and severity increase with age, reaching a prevalence of 70% of over-65 years-old in the USA , and pro1H NMR to identify whether saliva contained greater concentrations of any particular metabolites which could serve as biomarkers for diagnosing and monitoring GBL and PD and to study a posible association between both diseases.The aim of this study was to use This case-control study was approved by the Ethics Committee of the Hospital Clínico Universitario of Valencia, Spain  in accordance with the Declaration of Helsinki of 1964 and subsequent amendments by the World Medical Association. The case group comprised hospitalized patients with brain tumors awaiting surgery in the neurosurgery unit of this hospital. Following the operation, the suspected diagnosis was confirmed. The control group was composed of patients from the University of Valencia dental clinic. Oral examination and saliva sampling were performed in both groups.All the participants of legal age (18 years or over) were given an informed consent document with all the information concerning the study, to be signed voluntarily before taking part. For the control group, those who had taken antibiotics in the past six months, had fewer than eight teeth (excluding third molars), were pregnant or, in general, presented any condition that could lead to error like cardiovascular diseases, diabetes mellitus, rheumatoid arthritis, chronic obstructive pulmonary disease, pneumonia, chronic kidney disease, metabolic syndrome, obesity and Alzheimer´s disease, were excluded from the study . The casSaliva samples were obtained in the early morning to avoid the introduction of exogenous agents into the oral samples. The participants had not ingested any food, or chewed gum, or brushed their teeth or used any oral hygiene product in the two hours before the sample was taken, and had not smoken for at least one hour before. To collect the saliva samples, we used the “draining method”: the participants were seated comfortably for a few minutes in a resting position with their heads tilted slightly forward, in a quiet environment to avoid non-test stimuli. The slightly parted lips allowed the saliva to fall into a wide-necked sterile container. The liquid collected was then transferred with a pipette to a sterile 1.5 mL Eppendorf tube and was frozen immediately at -80°C until the NMR measurements were made ,20.http://www.hmdb.ca) and the Chenomx spectral database contained in Chenomix NMR Suite 8.1 .The data acquisition and processing were conducted as previously described by Galbis-Estrada et al. . Forty-eChemometrics statistical analyses were performed using in-house MATLAB scripts and the PLS Toolbox 6.7 . Metabolite levels were computed from the raw (untransformed) data and expressed as mean ± SD (standard deviation). T-Student’s test was used to determine the statistical significance of differences between the means in both of the cases, and the control group and ANOVA to estimate the differences between the three categories of periodontal status. A chi- squared was used for comparative proportions. The significance level was p < 0.05. Principal component analysis (PCA) and projection to latent structures for discriminant analysis (PLS-DA) were applied to the NMR spectral datasets. Results were cross-validated using the leave-one-out to evaluate the accuracy of each classification model ; in eachTen participants met the requirements for assigning the case group. This was performed by 1 male (10%) and 9 females (90%) in which the average age was 54.7 years old, range 26–78. In contrast, the control group comprised 120 participants of whom 49 were males (40.8%) and 71 were females . The average age was 51.8 years old, range 19–81 .http://www.hmdb.ca) and the Chenomx spectral database contained in Chenomix NMR Suite 8.1 sofware . The databases compare metabolites together with their respective concentrations based on a known reference signal, in this study we used TSP, 32 mM. A sample 1H NMR spectrum of saliva from a participant is shown in The identification and quantification of the saliva metabolite concentrations were made using the Human Metabolome Database , a total of 39 subjects were placed in group 1 , 59 in group 2 (gingivitis/early periodontitis) and 32 in group 3 (moderate/advanced periodontitis). A total of 68 metabolites were assigned, quantified and included at an ANOVA test . On compNumerous metabolites have been proposed for diagnosing, monitoring and treating inflammatory diseases. Identification and quatification leves of N-acetyl aspartate (NAA), choline, glutamate, glutamine, lactate, alanine, glucose, inositol, creatinine and lipids have been useful in previous studies to separate glial tumors by type and grade, and determine the choice of therapy and treatment efficacy to evaluate the progression or remission of GBL –25. The Short chain fatty acids such as butyrate, caproate, isocaproate, propionate, isovalerate and lactate play an important role in periodontal disorders. They are end-products of bacterial metabolism and have been strongly linked to deep periodontal pockets, loss of insertion, bleeding and inflammation. The acids prevent cell division, making repair difficult and favoring junctional epithelium degeneration processes, which in turn allows the entry of pathogens and the formation of periodontal pockets. These bacterial metabolites stimulate an inflammatory response and the liberation of cytokines. At cell level, they inhibit leukocyte apoptosis and cell proliferation in the gingival epithelium and endothelium, preventing their repair. . As has 1H NMR or LS-MS to identify metabolites related with PD, collect and analyze saliva samples seems to be a good and useful method to follow-up different diseases due to the fact that it is an easy, fast and non-invasive option, and its results are similar to those obtained from serum analysis or tissue cells cultures. There are a lack of studies in screening saliva to find biomarkers of GBL. In this study, we used 1H NMR but other complementary analytical platforms from the same sample, as such Mass Spectrometry, would be necessary to conclude if saliva could be used in the screening of GBL.The present study found significant differences in some metabolites in saliva of GBL and PD patients but any association between GBM and periodontal status was found. Sucrose and propionate in GBL patients and caproate, isocaproate-butyrate, isovalerate, lacatate+proline and proline in PD patients, were very significantly increased . Previous studies have analyzed saliva using S1 TableThe statistically significant ones are marked * p < 0.05 and ** p < 0.01.(DOCX)Click here for additional data file.S2 TableThe statistically significant ones are marked * p < 0.05 and ** p < 0.01.(DOCX)Click here for additional data file.


Moreover, our sensor with such an unprecedented response capability can be operated as a barometric altimeter with an altitude resolution of about 1 m. The outstanding behaviors of our devices make nanoparticle arrays for use as actuation materials for pressure measurement.Tunneling conductance among nanoparticle arrays is extremely sensitive to the spacing of nanoparticles and might be applied to fabricate ultra-sensitive sensors. Such sensors are of paramount significance for various application, such as automotive systems and consumer electronics. Here, we represent a sensitive pressure sensor which is composed of a piezoresistive strain transducer fabricated from closely spaced nanoparticle films deposited on a flexible membrane. Benefited from this unique quantum transport mechanism, the thermal noise of the sensor decreases significantly, providing the opportunity for our devices to serve as high-performance pressure sensors with an ultrahigh resolution as fine as about 0.5 Pa and a high sensitivity of 0.13 kPa Designing reliable piezoresistive pressure sensors based on percolative nanoparticle (NP) arrays remains a challenge. Here, the authors propose a percolative NP array sensor deposited on a flexible membrane with ultra-high sensitivity and resolution by modifying the thickness of the membrane. Electromechanical pressure sensors consist of two essential components: a membrane and a transducer element, which converts the applied pressure to an electrical signal change. Most recently, a wide variety of materials and nanostructures such as two-dimensional layers3, nanotubes6, nanofibers8, nanoparticles (NPs)10, and even composited conductive rubbers11 were focused to be used in these devices. Piezoresistive sensing is the most frequently used transduction mechanism in these pressure sensors12, owing to advantages such as direct current input, high yield, simple structure and manufacturing process, low cost, scalable, as well as easy signal collection14. These piezoresistive sensing elements undergo a change in their internal resistance when they are stressed, which breaks the ohmic contact or forms new defects in the materials. Generally, these piezoresistive sensing elements are hard to distinguish external pressure changes lower than 100 Pa, since the piezoresistive mechanism does not work if the external pressure change is tiny16. There is a tremendous interest to develop MEMS integrated pressure sensors that allow for atmospheric applications with a very high resolution of sub-10 Pa. With such a resolution, an altitude difference of about 1 m can be distinguished by barometric measurement.Precision pressure sensors are essential to many micro-electro-mechanical systems (MEMS) devices, with applications in various areas. Currently, the development of smart systems and wearable devices has drawn tremendous attention toward the high-resolution MEMS integrated pressure sensors working stably on atmospheric pressure18, humidity sensors19, as well as force and mass sensors20. In the closely spaced NP arrays, the spacing of the adjacent NPs is so small that the electron transports between NPs are dominated by tunneling or hopping22. There are a large number of percolative paths existing in the disorder NP arrays. Since the quantum tunneling or hopping is extremely sensitive to the inter-particle spacing, the percolative paths could be broken or regenerated by a tiny change in the geometries of the NP arrays. As a result, the conductance of percolative NP arrays is sensitively related to the deformation of the substrates on which the NPs deposit23. It is reasonable to assume that such mechanism is applicable to a piezoresistive pressure sensor by fabricating percolative NP arrays on flexible membranes as transducer elements.Recently, percolative NP arrays have been used as piezoresistive transducers of ultrasensitive mechanical sensors, such as strain sensors28. The device characterizes with an extremely high resolution of about 0.5 Pa. Working as a barometric altitude sensor, it demonstrates the ability to distinguish altitude difference of about 1 m. While the majority of the piezoresistive pressure-sensing devices today use doped silicon transducers wherein they undergo a change in their carrier mobility when they are stressed, our devices offer an alternative with potentially higher pressure resolution in terms of higher sensitivity, reduced thermal disturbance, and decreased power consumption with a larger resistance of about 10 MΩ.In this paper, we realize a new configuration of piezoresistive pressure sensor fabricated from percolation-based conductive nanostructures. Differing from current piezoresistive pressure gauges, these devices transduce the external pressure on the elastic membrane on which the NPs deposited to the change of the tunneling conductance across the NP percolating networks29. A quarter cross-sectional view of our sensor is shown in Fig. 10. These NPs formed a discontinuous film in a disordered manner on a highly deformable membrane such as polyethylene terephthalate (PET) with prepatterned interdigital electrodes (IDEs). These can be considered as percolation pathways that conduct electric current distinguishable from the leakage current when a fixed voltage is applied24. The strain-sensing mechanism of this structure comes from the deformation-dependent percolation morphology over the IDEs. By applying an external pressure, a small deformation of the PET membrane induces a change in the inter-particle spacing, enabling more or fewer conductive percolation pathways, thus leading to a change in the electron conductance, as shown in Fig. Similar to typical configurations of pressure sensors, the architecture of our pressure sensor is comprised of a strain gauge fabricated directly on the surface of the membrane and hermetically encapsulated on a vacuum or gas-filled reference cavity31, considering the similarity between the coverage of the NP assembly and the particle filling fraction used in the percolation model, both of which increase with the deposition time. In our device, the electrodes cover an area ranging from several square millimeters to several ten square millimeters, resulting in a huge aspect ratio  of the inter-electrode gaps. This morphology leads to a rapid increase of the conductance after the NP coverage reaches the percolation threshold, which is determined by the electrode separation, due to the formation of a large number of conductive percolation pathways (or say closely spaced NP chains across the electrodes). Furthermore, due to the quantum tunneling nature of electron transport, the development of the conductance during NP deposition is not only dependent on the geometric filling pattern of the NPs but also dependent on the distribution of inter-particle gaps along the conductive percolation pathway, which also changes with the increase of the deposition mass. As a result, a finely gradual change in the slope of the conductance evolution curve reported in Fig. The flexible strain-sensing element Fig.  was fabrTo analyze the micro-morphological characteristics of NPs, images from the scanning transmission electron microscopy (STEM) using a high-angle annular dark field (HAADF) detector Fig.  and the 33, the high mobility and easy coalescence behavior of gold NPs leads to large instability when they were used to constitute percolative conducting NP arrays.Generally, NPs of various metals can be used as the piezoresistive sensing medium. In the present research, palladium (Pd) NPs were used in preference owing to their less coalescence  and high-resolution transmission electron microscopy (HR-TEM) characterizations demonstrated that there is a PdOx layer of 0.5 nm in thickness formed on the NP surface  versus ΔP, where ΔG = G − G0, in which G and G0 denote the conductance with and without an applied differential pressure ΔP (with reference to atmospheric pressure), respectively. We first discuss the situation of a sensor with a 0.05-mm-thick PET membrane. Over the whole applied pressure range, our sensor showed a steady response to static pressure, and the conductance under each pressure was constant /ΔP) could be used to characterize the sensitivity S of the pressure sensor32. For smaller differential pressures (lower than 60 Pa), there is an approximately linear relationship between the response and the applied pressure, with a pressure sensitivity value S = 0.13 kPa−1. Above 60 Pa, the sensitivity dropped to 0.049 kPa−1. A response drop in sensitivity at higher pressures has been widely observed in recently reported pressure sensors37. In our sensor devices, the decrease in sensitivity might be attributed to the transition of the deformation behavior of the PET membrane.A home-made system was used to test the sensing performance of the sensing elements as shown in Supplementary Note 38. This could be proved by the changes of relative conductance influenced by different strain, as shown in Fig. For a thin film assembly of NPs on a flexible membrane, a compressive strain may induce a decrease in the mean distance to adjacent NPs, resulting in an increase in the conductance of the NP array, as shown in Fig. Back to the pressure sensor device, the strain generated on the PET membrane under pressure is not such simple. Since the edge of the PET membrane supported on the cavity is constrained, inhomogeneous deformation is generated on the membrane under applied pressure. We find that when a pressure is applied to the PET membrane, a compressive strain is generated from the center of the membrane while a tensile strain is exerted on the surrounding area. For convenience in analysis, we pay close attention to the cross section across the center of the circular membrane, as depicted by the schematic diagram of Fig. The inhomogeneous deformation of the membrane under pressure induces an inhomogeneous distribution of the inter-particle distance changes in the NP arrays. The conductance measured across the electrodes is an integration of the electron transport over all the conductive percolation pathways, which contain various inter-particle distances characterized with a complex function of position and pressure. Therefore, the response of conductance to pressure is no more a simple exponential function of pressure. At a smaller applied pressure, the compressive strain dominates the main area of the membrane, so that the whole NP array undergoes a conductance enhancement. An approximately linear dependence between conductance and pressure is observed. With increasing applied pressure, a transition from compressive to tensile strain can be observed as the position changes from center to edge of the membrane see Fig. . The extσ of 0.0024%.  This indicates that the sensor could resolve pressure changes as small as 1.5 Pa /(ΔG/G0)) without difficulty. This high stability and repeatability were also demonstrated in a compression test on the NP-coated PET membrane-based strain-sensing element, wherein the conductance response characteristic did not show any evident changes after repeated compressing for over at least 500 cycles . The root mean square (RMS) noise at different applied pressures was calculated from the fluctuations in ΔG/G0, as shown in Fig. 2f39. It can be seen that up to 60 Pa applied differential pressure, the RMS noise is always lower than 0.005% and remains fairly constant with pressure, making the noise-limited pressure resolution of the sensor as small as 0.38 Pa. Figure G. This relative change in conductance was well above the conductance fluctuation levels, so the reversible decrease and increase in G upon loading could be clearly distinguished from the random electrical noises. This indicates that our sensor has the ability to reliably detect pressure variations as low as 0.5 Pa.We now look at the resolution of the pressure measurement of the sensor. Generally, the random electrical noise in a piezoresistive sensor, which is dominated by thermal and flicker noise, sets the fundamental lower limit of its piezoresistive transducer resolution5 , graphenes43, PtSe23, and GaAs44 is shown. It is clear that the sensitivity of our devices is among the highest category. The more remarkable is that our sensors show an excellent resolution which is nearly three orders of magnitude higher than that of most of the others44. It is known that the ability to detect subtle pressure variations in the regime from 1 Pa to 1 kPa is crucial for many modern applications. The ultrahigh resolution realized in this paper is a significant improvement in current sensing capabilities.In Fig. 45. We also investigated how the thickness of the PET membrane influenced the effective pressure regimes and sensitivity.A report has shown that modifying the mechanical and geometrical properties of the flexible substrates could change the measuring range of sensors46. This is true when the applied pressure is small. The pressure-response curves measured for sensors having three different PET membrane thicknesses are compared in Fig. −1 for the 0.1 mm PET membrane, and for the 0.25 mm PET membrane the sensitivity is 0.0042 kPa−1. However, at higher pressures, the sensitivity of the pressure sensor with thinner PET membrane dropped noticeably due to the expanding of the tensile strain regions, as discussed above. Since thinner films tend to be subject to significant visco-elastic creep or even plastic deformation at higher applied pressure . But at higher pressure, the deformation of the membrane may be plastic so that significant hysteresis emerges , where l is the spacing of the adjacent NPs and β is a size- and temperature-dependent electron coupling term52. The exponential relationship means that NP arrays respond to a tiny pressure-induced deformation of the actuation membranes with atomic-scale sensitivity. Furthermore, the electrical potential energy built between adjacent NPs due to electron charging could sufficiently reduce the random transport of electrons having energy less than kBT (kB is the Boltzmann constant), which contribute to the lower energy portion of the statistical distribution of electron energy, although no Coulomb blockade was observable at room temperature. As a result, thermal noise may decrease significantly, which enables an increased sensing resolution.The high sensitivity and ultrahigh resolution realized by our sensor can be attributed to the nature of the current transport, which is dominated by electron tunneling or hopping  of the inter-electrode gaps. Pd NPs were generated from a home-made magnetron plasma gas aggregation cluster source in argon stream at a pressure of about 80 Pa and extracted to a high vacuum deposition chamber with a differential pumping system. Some deposition parameters are displayed in Supplementary Table The fabrication of sensing elements is shown in Supplementary Note The piezoresistive pressure sensor was connected to a pressure controller for applying different pressures (see Supplementary Note The commercial software ANSYS 19 was chosen to perform FEA (see Supplementary Note ε could be calculated (more details are given in Supplementary Note The actuation layer was removed from the sensor. Strains were generated from the deformations of the actuation layer which was subjected to a micrometer step by step (see Supplementary Fig. Supplementary InformationPeer Review FileDescription of Additional Supplementary Filessupplementary movie 1Source Data


Gs). Gs, which so far was only predicted theoretically, is inversely proportional to such interactions. As model systems, we use HeLa and HaCaT tissue cultures with water and with an aqueous DMSO solution. The measurements are done using Centrifugal Adhesion Balance (CAB) when set to effective zero gravity. As expected, the addition of DMSO to water reduces Gs. This reduction in Gs is usually higher for HaCaT than for HeLa cells, which agrees with the common usage of DMSO in dermal medicine. We also varied the rigidities of the tissues. The tissue rigidity is not expected to relate to Gs, and indeed our results didn’t show a correlation between these two physical properties.The pharmaceutical industry uses various solvents to increase drug penetrability to tissues. The solvent’s choice affects the efficacy of a drug. In this paper, we provide an unprecedented means of relating a solvent to a tissue quantitatively. We show that the solvents induce reorientation of the tissue surface molecules in a way that favors interaction and, therefore, penetrability of a solvent to a tissue. We provide, for the first time, a number for this tendency through a new physical property termed Interfacial Modulus ( Water is a commonly used medium for transdermal drug delivery because tissue hydration appears to increase transdermal delivery of both hydrophilic and lipophilic permeants5. However, it is not a universal medium because it does not increase the drug percutaneous absorption6. Thus, in many cases, there is a desire to increase the efficacy of drug delivery7. One long-standing approach to increase drugs penetrability to the skin has been to use penetration enhancers that interact with skin constituents to promote drug flux. Most commonly used enhancers are water, azone, pyrrolidones, fatty acids, alcohols, and sulfoxides of which Dimethyl sulfoxide (DMSO) is the most prevalent example10. Sulfoxides in general, and DMSO in particular, have been proven to be better at transdermal drug delivery compared to water13.Drug delivery via transdermal, intramuscular and subcutaneous injections are often performed instead of oral administration, especially for administering therapeutic peptides or proteinsin vitro and in vivo applications primarily due to its enhanced solubility for pharmaceutical reagents, since many drugs drugs are not soluble in hydrophilic solvents14. It is also used as an anti-freeze agent (cryo-preservation)15. In addition of being an effective solvent for small molecules, DMSO is also capable of dissolving macromolecules such as peptides and proteins2 and facilitating drug diffusion across cell membranes comprised of lipid bilayers. Chemically, it is a powerful aprotic solvent which hydrogen bonds with itself rather than with water; it is colorless, odorless and hygroscopic and is often used in many areas of pharmaceutical sciences as a “universal solvent”3. Moreover, it is cost effective to synthesize, is stable at room temperature conditions and has a workable cytotoxicity of up to 10% for most biomedical purposes.DMSO is a common drug solvent for 13.In this paper we quantify DMSO’s tissue penetrative capacity when mixed with water. This penetrative capacity of the solvent influences its wetting behavior on the substrates and effect the drop pinning. For instance, HaCaT substrate represents cell line from an adult human skin and since skin acts as a barrier to penetrating molecules, chemical permeability enhancers such as DMSO are added to deliver active molecules into or via the skinstratum corneum, are the main barrier to penetration of exogenous substances through the skin10. Yet, evaluating the degree of enhancement of such agents currently lacks a quantitative method. In this paper we show a method for quantifying penetration enhancers, and demonstrate it on DMSO and water. We study the interaction of the surface molecules of HeLa and HaCaT tissue cultures with water and how addition of DMSO to water can influence this interaction. HaCaT substrates are cell line from an adult human skin and HeLa substrates are cervical tumor cell line. Rigidities of HeLa and HaCaT cell substrates are chosen such that they mimic their respective in vivo conditions while water and DMSO are chosen for their pharmaceutical applications. Both solvents are known to not interfere with various drugs and can efficiently interact and penetrate tissues along with other active agents13. To quantify the way addition of DMSO to water enhances the tissue penetrative capacity of drugs13, we use the concept of the interfacial modulus (Gs) as explained below.Though a methodic choice of solvents is important for the drug delivery purposes, and there are studies that target the various parameters in the problem, still the solvent penetration efficacy is not quantifiable. For example, it is known that the lipids of the topmost layer of the skin, the 19 and assumes surface deformation. This approach is particularly sensitive to the normal force that acts on the drop, and therefore requires measurements at effective zero gravity. However, it allows the determination of the interfacial modulus according to:f∥ is the lateral force required to slide the drop along the surface, γLV is the liquid-vapor surface tension, θ is the contact angle that the drop adopted when it was resting on the surface before the onset of motion, θR and θA are the drop receding and advancing contact angles, respectively as shown in Fig. Gs  represents the tendency of the surface to resist interacting with the liquid. It can, therefore, serve as a measure of solvent’s affinity to a certain substrate17. The determination of Gs is done through measurements of drop retention forces at effective zero gravity, i.e. at zero normal force. The force considered in Eq. . The normal component, γLV sinθ creates a ridge at the triple line, that although doesn’t affect the macroscopic contact angle, it does lower the rate of liquid wetting the surface, makes solids exhibit contact angle hysteresis, can increase the drop retentive force and exhibit time effect23 at solid-liquid interface.This approach considers outmost surface layer deformation which is proportional to the Laplace pressure inside the drop and occurs in the normal direction time effect, we study lateral adhesion of a drop after allowing it to rest undisturbed for a fixed waiting time (tstill) duration. We use the Centrifugal Adhesion Balance (CAB)26 so that the normal components of the gravitational and centrifugal forces cancel each other, namely a state of zero normal force (i.e. effective zero gravity), and their lateral components are gradually increased. Figure To study Figure f⊥ and f∥ are the normal and lateral force acting on the drop, respectively, m is the drop’s mass, ω is the CAB angular velocity, R is the drop’s distance from the CAB’s center of rotation, g is the gravitational acceleration, and α is the tilt angle with respect to the horizon. For the experiments done in this study, f⊥ = 0 was maintained and f∥ was gradually increased. The substrates used were HeLa and HaCaT tissue culture cells.CAB manipulates normal and lateral forces according to following equations:2. After reaching 100% confluency, cell samples were crosslinked and preserved in 4% formaldehyde for subsequent experiments. Liquid solution used are deionized (DI) water  ≤ 0.7 × 10−6 Ω−1 cm−1) and 10% DMSO-90% water solution  for their biological significance.Culture human cell lines HaCaT and HeLa  were obtained from the American Type Culture Collection (ATCC). The cells were seeded on silicone plates mimicking physiological tissue stiffness with rigidity of 2 kPa, 8 kPa and 64 kPa (manufactured by MuWells inc) and maintained in DMEM supplemented with 10% fetal bovine serum at the condition of 37 °C and 5% COGs, there is a need to have the tissue in a dry form so that its outer side is more hydrophobic, and its more hydrophilic functional groups are buried inside the layer. One way to achieve this, is to expose the tissue to air over a long time. A quicker way is DI water and ethanol rinse as explained above.The cell cultures used are cleaned and dried by a DI water rinse followed by 70% (30% DI water) ethanol rinse and finally a 90% (10% DI water) ethanol rinse. This step is crucial since biological tissues are naturally wet, both water and DMSO aqueous solutions would wet them completely and contact angles couldn’t be measured. Therefore, to measure Extra care was taken to prevent the contamination of the tissue samples or alter their surface properties due to human error. However, it is important to note that even in a controlled environment the cell distribution in the substrate cannot be controlled and has a random nature . The drGs values of each substrate - liquid pair are measured from values taken at that moment.Figure tstill, during which the drop is resting motionless on the substrate and the CAB is still. After that, the CAB’s arm starts rotating, the sliding force on the drop increases and the drop is still motionless while maintaining zero effective gravity. The time that elapses from the moment the CAB’s arm started rotating till the moment the drop started to slide is noted as tactive. Thus, the total time that the drop is resting on the surface prior to sliding, trest, is trest = tstill + tactive. Figure f∥ required to slide a drop as a function of drop resting time (trest).As can be seen in Fig. f∥, required to slide water and aqueous DMSO on HeLa tissue cultures. The common feature in Fig. trest. With the increase in resting time, the retention force increases  and reaches, or clearly approaches, a plateau. This dependence of retention force on resting time or time effect is observed for HaCaT-Water and HaCaT-10% DMSO system as well  measurements at effective zero gravity. The CAB study also shows that the drop’s lateral retention force increases with the time the drop rests on the surface (drop resting time) and eventually reaches, or clearly approaches, a plateau. This time effect was observed for both HeLa and HaCaT tissue cultures, and is yet another feature of the interfacial modulus which describes the resistance of a solid (or tissue) surface to interact with a contacting liquid. The higher the interaction, the more significant is the solid surface molecular re-orientation that gives rise to the interfacial modulus. The interfacial modulus is not expected to be a function of the tissue’s rigidity, and indeed we found no correlation between these properties. This study demonstrates how to quantify interactions of any tissue with any solvent  or any tissue penetration enhancers.The interactions of water and DMSO solution to HeLa and HaCaT tissue cultures of varying rigidities was investigated. While it was known that DMSO increases the affinity of the solvent to the tissue, such knowledge was not quantitative as of yet. Here, we quantify this property of DMSO by measuring the interfacial modulus -


Smartphone-based technologies for medical imaging purposes are limited, especially when it involves the measurement of physiological information of the tissues. Herein, a smartphone-based near-infrared (NIR) imaging device was developed to measure physiological changes in tissues across a wide area and without contact. A custom attachment containing multiple multi-wavelength LED light sources , source driver, and optical filters and lenses was clipped onto a smartphone that served as the detector during data acquisition. The ability of the device to measure physiological changes was validated via occlusion studies on control subjects. Noise removal techniques using singular value decomposition algorithms effectively removed surface noise and distinctly differentiated the physiological changes in response to occlusion. In the long term, the developed smartphone-based NIR imaging device with capabilities to capture physiological changes will be a great low-cost alternative for clinicians and eventually for patients with chronic ulcers and bed sores, and/or in pre-screening for potential ulcers in diabetic subjects. Chronic wounds—also termed as ulcers—are wounds with a full thickness in depth and a slow healing tendency. Chronic wounds are a silent epidemic that affect a large fraction of the world, and ~1–2% of the population will experience a chronic wound during their lifetime in developed countries [The clinical gold-standard assessment of wounds during their periodic treatment employs visual inspection of chronic wounds to assess wound healing status. Visual clinical assessment of the wound occurs by its color, degree of epithelialization, and size reduction across weeks of treatment. It is a non-objective approach with no systematic or digitized tracking of healing status. Oxygen is a vital factor that is required to enhance wound healing . DetermiSubclinical wound assessment tools include histological detection—to characterize infection, Doppler ultrasound —to measuMore recently, various non-invasive optical imaging techniques have been developed to measure oxygenation in and around the wounds. These include hyperspectral imaging (HSI), multispectral imaging (MSI), diffuse reflectance spectroscopy (DRS), and near-infrared spectroscopy (NIRS) ,5. HSI aTranslating the above developed imaging technologies for wound care management in low resource settings is further challenging due to limited resources/income and affordability for such expensive imaging approaches. Herein, with a global focus in mind, a low-cost smartphone-based near-infrared optical imaging technology was developed and its feasibility tested to obtain physiological information from the wound site apart from visible clinical changes. Physiological changes manifest prior to visual reduction in wound size, allowing potential detection of serious complications early on.Near-infrared optical imaging is an emerging non-invasive and non-ionizing technology that can map the hemodynamic changes in the site of interest  even up to a few centimeters deep. The technology uses near-infrared (NIR) light between 650 and 1000 nm, which is minimally absorbed and preferentially scattered allowing deep tissue imaging. Multi-wavelength NIR images map the spatial and temporal distribution of the optical properties . NIR optical imaging technology has been used in various applications such as cancer diagnostics, functional brain mapping, and more recently in the area of wound imaging. In the area of wound imaging, both spectroscopic point-based NIR imaging  and areaRecently, researchers have developed smartphone-based apps for 2D and 3D wound image analysis ,14, to tIn the area of medical imaging, there are a few smartphone-based imaging technologies that have been developed to cater to various applications ,21,22,23A near-infrared smartphone-based imaging system or SPOT device see  was deveAn overview of the data acquisition and analysis steps is given in The device  was fastened to a table side for stable imaging and maintained approximately 3” above the imaging surface. The ambient light was lowered during imaging studies in order to minimize background noise. The smartphone’s camera was maintained in auto focus mode and high dynamic range (HDR) mode of acquisition was selected during imaging studies. The sampling rate (in video mode) was chosen to be 60 fps and images of 1920 × 1080 (5M) pixels were captured. The custom-attachment device had a manual switch to control the LED driver with a 5 s delay. The delay allowed for the user to start the camera and the camera to auto-focus and stabilize. The LED driver controlled the white light LED and the multi-wavelength LEDs that simultaneously multiplex at 2.5 Hz frequency to emit each wavelength independently. In parallel, the camera was continuously capturing the diffuse reflectance images at 60 fps during a 4 s cycle. The cycle was repeated three times for each case, with each cycle preceded by a white light flash at the same frequency of 2.5 Hz during multiplexing. The white light was also programmed to flash at the end of the three cycles, thus acting as an indicator that data acquisition was complete. The LED driver was programmed to automatically stop after the three cycles, whereas the smartphone camera was manually stopped. In future, the LED driver and camera controls will be automated and synchronized via an app for ease of imaging. The diffuse reflectance signals acquired at a frame rate of 60 fps  were uploaded from the camera and further image analysis was carried out on an external computer (desktop or laptop).The 60 fps video file included the diffuse reflectance signals from all the four wavelengths . The diffuse reflectance signals (or intensity) of the red color channel of each frame were averaged and plotted across the number of frames  is a widely used image processing technique that is implemented in medical imaging data to reduce the image dimensionality. It extracts relevant details by reducing the dimensionality of the data via a simple implementation. SVD is so closely related with principal component analysis (PCA) that the techniques can often be interchangeably used. However, SVD is a more general method and robust approach to understand changes of basis . SVD hasX). SVD was used as an approximation for a matrix X of a given full rank, where X (M × N) is decomposed into orthogonal matrices U (M × M) and V (N × N) and a diagonal matrix S (N × M), as shown in Equation (1).Herein, SVD was implemented to the diffuse reflectance data at each wavelength  and the orthogonal U and V matrices, as a reduced low ranking matrix (represented as matrix A for the Kth EV), given by Equation (2).The diagonal matrix represents the significance of each eigen value (by an assigned weight), organized with the most significant eigen values (EVs) in descending order. The matrix, A low-ranking image implies majority of the information is stored within a few EVs and can be represented by small set of these dominant components . Each EVThe resulting reconstructed images of diffuse reflectance signals  were cropped to only the field of interest. The data were normalized and coregistered onto the white light image for anatomical representation. Coregistration was achieved via optimizing intensity-based algorithms with an initial step size of 0.02 at 300 iterations (using built-in coregistration-based functions in MATLAB). A preliminary analysis of the most significant EVs and their role in image reconstruction is described in Venous occlusion studies are a standard validation technique widely employed to demonstrate the feasibility of physiological measuring imaging technology. It has been widely used by various researchers for various imaging studies in the past ,30,31,32In this Institutional Review Board (IRB) approved study, four healthy control subjects over 18 years of age were recruited and imaged in the lab using the smartphone-based imaging device. Initially, the subject was seated in a relaxed position with arm on bench top and a pressure cuff at the bicep for venous occlusion. A fiducial marker was placed on the subject within the field of view (for coregistration purposes). The diffuse reflectance signal was acquired under rest conditions, and after 45 s of occlusion at 160 mm Hg. The arm cuff pressure was released rapidly after acquiring the second image and the last image was acquired within 2 s of cuff release. A schematic of the study and the time stamp at which diffuse reflectance images were acquired is shown in A quantitative analysis was performed to determine if the difference in the diffuse reflectance data across the three time stamps using various EVs was significant. Initially, a region of interest (ROI) was selected in similar regions (from the wrist below) in subjects 1, 2, and 4. The ROI remained constant across the time stamps in each of the above subjects . In each ROI, 17 30 × 30 pixel boxes were selected  as shown in Single value decomposition (SVD) was applied to images acquired at rest across all four subjects. A sample plot of the intensity of the EVs  at each EV is given in Reconstructed images of diffuse reflectance at a given wavelength (here only 690 nm data were used during preliminary assessment of the device) were compared across the three time stamps . Similar results were observed across the four subjects, where the optical images varied across the time stamps when 3:15, 4:15, and/or 5:15 EVs were used and further removal of EVs diminished that difference. The results of the quantitative analysis are shown in Upon further removing the EVs , the qualitative pseudo-color plots from rest did not appear to depict physiological signals. Hence quantitative analysis was not carried out across these EV ranges. While subject 1, 2, and 4’s wrist was imaged, subject 3’s dorsal of the hand was imaged during occlusion (to determine if the differences in diffuse reflectance across the time stamps was significant) at a different location on the hand. From qualitative pseudo-color plots in Comparing the optical images across the rest, occlusion, and release, it was consistently observed that the diffuse reflected signal reduced after 45 s of occlusion, when compared to rest. Similarly, a significant increase was observed upon immediate release after the 45 s occlusion across all the four subjects. Typically 690 nm predominantly signifies deoxy-hemoglobin concentration changes. Upon occlusion, the deoxygenated hemoglobin tends to increase in the occluded region causing an increased absorption (or decreased diffuse reflectance) of the 690 nm NIR light. Upon immediate release, there is possibly a rapid decrease in deoxygenated hemoglobin as oxygen rich blood flows through the tissue, causing a reduction in its absorption (or increase in diffuse reflectance).An NIR-based SPOT (smartphone-based oxygenation tool) device was developed to image for physiological changes in, in- vivo tissues without contact. The custom attachment that contained all the relevant imaging components  was used along with the smartphone’s camera —collectively the SPOT device—to acquire multi-wavelength diffuse reflectance signals. The ability of the SPOT device to observe physiological changes was validated via occlusion studies. Upon employing SVD-based noise removal algorithms, subsurface information that pertains to physiological changes was observed distinctly when using EVs 3:15, 4:15, and/or 5:15. The differences in the diffuse reflected signal in response to occlusion were similar across all the imaged subjects. Future work will include extensive quantitative studies to show the percentage of change in optical signals and its consistency during repeatability studies within the subject, across the subjects, and at different locations of the hand. Additionally, the multi-wavelength NIR images will be used along with modified Beer–Lambert’s law to obtain changes in oxy- and deoxy-hemoglobin concentrations along with oxygenation saturation maps (and hence the device is termed as smartphone-based oxygenation tool—SPOT).The SPOT device is currently modified to synchronize source and detector operations and automate image acquisition via custom-developed application software. In the current study, data corresponding to each wavelength were manually extracted, causing delays in the entire data processing steps. Our ongoing studies are attempting to automate the data extraction process using machine learning algorithms, such that the required attributes are extracted and frames appropriately labeled automatically. Assessing wounds from a subclinical physiological perspective is a novel addition to smartphone-based technologies that augments wound care management, with a potential to predict serious complications early on, or periodically monitor the wound status in chronic cases. A smartphone-based imaging technology with capabilities to capture physiological changes (as a tissue oxygenation measuring tool) will be a great low-cost alternative for clinicians and eventually for patients with chronic ulcers, bed sores, and/or in pre-screening for potential ulcers in diabetic subjects.Both the authors are co-inventors on the patent related to the smartphone-based imaging technology and methodology described in this manuscript. The patent is currently filed by Florida International University.


Esophageal diverticula and esophageal fibrovascular polyps are uncommon clinical entities. While an asymptomatic presentation is possible, symptoms, when present, may be dissimilar in their gastrointestinal or respiratory characteristics. Additionally, these findings typically occur in different segments of the esophagus, with polyps occurring most frequently in the cervical esophagus and the midesophagus being the predominant location of pathologic diverticula.We report the case of a 55-year-old patient who presented with a two-year history of progressive dysphagia secondary to a large proximal to midesophageal mass. Workup included esophagography, computed tomography, and endoscopy with ultrasound and was initially consistent with a diagnosis of a large esophageal fibrovascular polyp. Upon operative exploration, the mass was found to be a midesophageal diverticulum associated with a leading lipoma. The patient was successfully treated with transthoracic stapled diverticulectomy. At postoperative follow-up the patient was tolerating oral intake with no symptoms of dysphagia.Esophageal diverticula are typically found in the midesophagus and are thought to arise from radial traction secondary to mediastinal inflammation. Esophageal fibrovascular polyps may result from tracheobronchial compression, and esophagography typically identifies a mobile intraluminal mass.Esophageal fibrovascular polyps and diverticula are rare, and a high index of suspicion is important in evaluation of these entities. Unlike distal esophageal diverticula which are often associated with gastroesophageal reflux disease, they are classically associated with chronic mediastinal inflammation and result from traction forces on the esophageal wall . HoweverWe report the case of a 55-year-old woman whose workup supported the diagnosis of a large FVP. On exploration, the lesion was found to be a midesophageal diverticulum traveling in the submuscular plane. The lesion was successfully managed with transthoracic diverticulectomy and buttressed closure.This work has been reported in line with the SCARE criteria .2A 55-year-old healthy woman was referred to our institution with a two-year history of progressive dysphagia to solids . She repPhysical exam and laboratory testing were unremarkable. Esophagography demonstrated a filling defect in the upper thoracic esophagus. Computed tomography (CT) demonstrated an 8 cm mass. Endoscopic ultrasound (EUS) demonstrated a pedunculated mass with a submucosal origin beginning at 20 cm from the incisors on the right side of the neck . The lesThe exploration began via a right cervical approach. The recurrent laryngeal nerve was identified and the cervical esophagus was mobilized. The mass was palpable on the posterior esophageal wall at the thoracic inlet. Upon a short myotomy, no stalk was identified and the mass could not be delivered to the neck. The cervical incision was closed and a right thoracotomy was performed. The mass was seen extending from the level of the azygos vein to the thoracic inlet. The esophageal muscular layer was intact. Following myotomy, the soft mass, which was densely adhered to the mucosa, was visualized and dissected from the underlying mucosa. It became evident that the mass maintained its attachment to a portion of the mucosa. Complete mobilization revealed the mass to be a lipoma at the tip of a large midesophageal diverticulum traveling in a submucosal plane. Repeat endoscopy demonstrated an ostium in the esophageal wall opening into a blind-ending pouch. The diverticulum was fully mobilized and resected using a stapler . MucosalThe patient was diagnosed with a large midesophageal diverticulum with a lead point lipoma. The patient’s postoperative course was uncomplicated. A postoperative esophagogram demonstrated no esophageal leak or obstruction. Pathology demonstrated a 7.5 cm diverticulum with a 4.5 cm lipoma without malignancy. At follow-up on the nineteenth postoperative day, the patient was tolerating a diet without dysphagia.3Fibrovascular polyps classically present as pedunculated masses arising immediately distal to the cricopharyngeus ,7,9. ResMidesophageal diverticula are found near the carina and classically have been attributed to radial traction from mediastinal inflammatory processes ,2. When This case is unique in its presentation in that workup supported a diagnosis of FVP. The intramural tract of the diverticulum mimicked the pedunculated stalk of a FVP. The diverticular ostium was collapsed and not identified on endoscopy until after full operative mobilization of the diverticulum. Unlike most reported cases of midesophageal diverticula, this was neither associated with mediastinal inflammation nor with an underlying motility disorder. The diverticular ostium was collapsed and not identified on endoscopy until after full mobilization of the diverticulum. The presence of a leading lipoma is also uncharacteristic. These findings highlight the importance of maintaining a high index of suspicion when evaluating a suspected FVP or midesophageal diverticulum, as well as astute use and interpretation of diagnostic imaging modalities in patient evaluation.The authors have no conflicts of interest to disclose.This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.MD Anderson Cancer Center Institutional Review Board – This investigation is exempt from ethical approval at our institution.Consent obtained.BS and GW contributed to conceptualization, study design, and manuscript drafting and editing. KM, EC, and RV contributed to data collection, data analysis, and manuscript drafting and editing.NA.Erin M. Corsini.Boris Sepesi.Not commissioned, externally peer-reviewed.