All electrospun fabrics based piezoelectric tactile sensor.

Tactile sensors have been widely used in the areas of health monitoring and intelligent human-machine interface. Flexible tactile sensors based on nanofiber mats made by electrospinning can meet the requirements of comfortability and breathability for wearing the body very well. Here, we developed a flexible and self-powered tactile sensor that was sandwich assembled by electrospun organic electrodes and a piezoelectric layer. The metal-free organic electrodes of thermal plastic polyurethane (PU) nanofibers decorated with multi-walled carbon nanotubes were fabricated by electrospinning followed by ultrasonication treatment. The electrospun polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) mat was utilized as the piezoelectric layer, and it was found that the piezoelectric performance of PVDF-TrFE nanofiber mat added with barium titanate (BaTiO3) nanoparticles was enhanced about 187% than that of the pure PVDF-TrFE nanofiber mat. For practical application, the as-prepared piezoelectric tactile sensor exhibited an approximative linear relationship between the external force and the electrical output. Then the array of fabricated sensors was attached to the fingertips of a glove to grab a cup of water for tactile sensing, and the mass of water can be directly estimated according to the outputs of the sensor array. Attributed to the integrated merits of good flexibility, enhanced piezoelectric performance, light weight, and efficient gas permeability, the developed tactile sensor could be widely used as wearable devices for robot execution end or prosthesis for tactile feedback.

TiO2hierarchical nano blooming-flower decorated by Pt for formaldehyde detection.

To achieve an ultra-low concentration formaldehyde detection at low temperature, a platinum (Pt) assisted TiO2hierarchical nano blooming-flower sphere material is synthesized through hydrothermal method. SEM and transmission electron microscope characterizations show that the diameter of the nano sphere was around 2µm with dissilient rods of 60 nm in diameter and 1µm in length on the surface. The response (Ra/Rg) achieved form this nanomaterial to HCHO is 1.08 (100 ppb) and 5.82 (5 ppm) at 130 °C without an involvement of any light source or solution. The relationship curve between the responses and concentrations shows regular exponential trend. The verification of sensor stability done by a 3 month reliability test shows no response-degradation. The optimal response and stability is attributed to the massive dissilient rods on the surface of TiO2spheres and the assistance of Pt as a catalyzer disperses to intensify the formation of depletion area on the surface of TiO2. This study provide an attractive and cost effective solution for the detection of HCHO in air at a relatively low temperature.

Adjuvant PD-1 inhibitor versus high-dose interferon α-2b for Chinese patients with cutaneous and acral melanoma: A retrospective cohort analysis.

The clinical efficacy of PD-1 inhibitors as an adjuvant treatment for Asian melanoma patients has not yet been determined. This retrospective study analyzed the clinical data of 90 Chinese patients with completely resected, stage III cutaneous or acral melanoma who received either adjuvant PD-1 inhibitor or high-dose interferon α-2b (HDI). Anti-PD-1 treatment resulted in significantly longer RFS and DMFS than HDI in cutaneous melanoma patients, with hazard ratios (HRs) (anti-PD-1 versus HDI) of 0.402 (95% CI, 0.183-0.886) and 0.324 (95%CI, 0.122 to 0.861) for RFS and DMFS, respectively. However, adjuvant anti-PD-1 treatment had no advantage over HDI in acral melanoma patients with HRs (anti-PD-1 versus HDI) of 1.204 (95% CI, 0.521 to 2.781) and 1.968(95% CI, 0.744-5.209) for RFS and DMFS, respectively. Adjuvant anti-PD-1 treatment yielded a significantly better prognosis than HDI in Chinese patients with stage IIIB/C cutaneous melanoma, but a significant difference was not observed in those with acral melanoma.

Thermal conductivity and interfacial thermal resistance in the heterostructure of silicon/amorphous silicon dioxide: the strain and temperature effect.

This article reports the thermal conduction properties of Si/a-SiO2 heterostructure with two different interfaces: weak and strong coupling strength through molecular dynamics simulation. The size and temperature dependencies on the interfacial thermal resistance of the weak coupling interface are larger than those of the strong coupling interface. The thermal conduction in Si/a-SiO2 shows strong anisotropy. The thermal conductivity, interfacial thermal resistance, and enhancement of the anisotropy can be modulated by changing the strains applied to the heterostructures. This work provides an optional way to design the silicon-based heterostructures considering heat insulation and heat dissipation.

Effect of grinding parameters on surface roughness and subsurface damage and their evaluation in fused silica.

Based on micro-indentation mechanics and kinematics of grinding processes, theoretical formulas are deduced to calculate surface roughness (SR) and subsurface damage (SSD) depth. The SRs and SSD depths of a series of fused silica samples, which are prepared under different grinding parameters, are measured. By experimental and theoretical analysis, the relationship between SR and SSD depth is discussed. The effect of grinding parameters on SR and SSD depth is investigated quantitatively. The results show that SR and SSD depth decrease with the increase of wheel speed or the decrease of feed speed as well as cutting depth. The interaction effect between wheel speed and feed speed should be emphasized greatly. Furthermore, a relationship model between SSD depth and grinding parameters is established, which could be employed to evaluate SSD depth efficiently.

Study of ZnS Nanostructures Based Electrochemical and Photoelectrochemical Biosensors for Uric Acid Detection.

Uric acid (UA) is a kind of purine metabolism product and important in clinical diagnosis. In this work, we present a study of ZnS nanostructures-based electrochemical and photoelectrochemical biosensors for UA detection. Through a simple hydrothermal method and varying the ratio of reaction solvents, we obtained ZnS nanomaterials of one-dimensional to three-dimensional morphologies and they were characterized using field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). To fabricate the UA biosensor and study the effect of material morphology on its performance, ZnS nanomaterials were deposited on indium tin oxide (ITO) conducting glass and then coated with uricase by physical absorption. Three kinds of working electrodes were characterized by cyclic voltammetry method. The effect of material morphology on performance of UA detection was investigated via amperometric response based electrochemical method based on enzymatic reaction. The ZnS urchin-like nanostructures electrode shows better sensitivity compared with those made of nanoparticles and nanoflakes because of its high surface-area-to-volume ratio. The photoelectrochemical method for detection of UA was also studied. The sensitivity was increased 5 times after irradiation of 300 nm UV light. These results indicate that ZnS nanostructures are good candidate materials for developing enzyme-based UA biosensors.

Revealing the Indispensable Role of In Situ Electrochemically Reconstructed Mn(II)/Mn(III) in Improving the Performance of Lithium-Carbon Dioxide Batteries.

Li-CO2 batteries are regarded as promising high-energy-density energy conversion and storage devices, but their practicability is severely hindered by the sluggish CO2 reduction/evolution reaction (CORR/COER) kinetics. Due to the various crystal structures and unique electronic configuration, Mn-based cathode catalysts have shown considerable competition to facilitate CORR/COER. However, the specific active sites and regulation principle of Mn-based catalysts remain ambiguous and limited. Herein, this work designs novel Mn dual-active sites (MOC) supported on N-doped carbon nanofibers and conduct a comprehensive investigation into the underlying relationship between different Mn active sites and their electrochemical performance in Li-CO2 batteries. Impressively, this work finds that owing to the in situ generation and stable existence of Mn(III), MOC undergoes obvious electrochemical reconstruction during battery cycling. Moreover, a series of characterizations and theoretical calculations demonstrate that the different electronic configurations and coordination environments of Mn(II) and Mn(III) are conducive to promoting CORR and COER, respectively. Benefiting from such a modulating behavior, the Li-CO2 batteries deliver a high full discharge capacity of 10.31 mAh cm-2, and ultra-long cycle life (327 cycles/1308 h). This fundamental understanding of MOC reconstruction and the electrocatalytic mechanisms provides a new perspective for designing high-performance multivalent Mn-integrated hybrid catalysts for Li-CO2 batteries.

An ultrasensitive isoprene gas sensor based on the In2O3/MoS2 nanocomposite prepared by hydrothermal synthesis.

Isoprene is one of the specific biomarkers of liver disease in human exhaled gas, which should be detected with a high response at an order of ppb in actual application. In this paper, the heterojunction between n-type In2O3 and MoS2 was proposed to improve the isoprene sensing properties. Both In2O3 and MoS2 were prepared by a hydrothermal method, and nanostructured In2O3 flowers and solid micro irregular MoS2 particles were mixed into the In2O3/MoS2 composite with a mol ratio of 6 : 4. The composite was characterized by EDS and XRD to confirm the element types and crystal types. The isoprene sensor was prepared by dipping the composite suspension on a ceramic substrate integrated with a sensing electrode and heating unit. The testing results of the sensor showed the highest response value of 1.8 to 100 ppb isoprene at 200 °C. Besides, the low detecting limit (less than 5 ppb isoprene) and excellent selectivity are also revealed, showing that the composite can be a good candidate sensing material for isoprene for application in breath analysis.

Clinical features and response to systemic therapy in NRAS-mutant Chinese melanoma patients.

PURPOSE: The prognosis of patients with NRAS-mutant melanoma is rather poor. Immunotherapy and targeted therapy have revolutionized anti-tumor therapy, especially for melanoma. In this study, we retrospectively summarized the real-world experience of systematic treatment for NRAS-mutant melanoma patients in this new era. PATIENTS AND METHODS: The respective cohort included NRAS-mutant melanoma patients with metastatic or unresectable disease of Sun Yat-sen University Cancer Center (SYSUCC) from January 2018 to July 2022. The data about the clinical features and impact for systemic therapy of NRAS-mutant patients were collected and analyzed. RESULTS: At data cutoff, 44 patients (19, 11, and 14 for acral, cutaneous, and mucosal ones, respectively) with NRAS-mutant were assessed. In addition, the median time of follow-up was 22.0 months. The immunotherapy-based combined treatment not only significantly improved the progression-free survival (PFS) (P = 0.006, HR 0.322), but was also accompanied by a higher objective response rate (ORR) (18.2%), disease control rate (DCR) (72.7%) than those of cytotoxic therapy or immunotherapy alone for advanced patients as first-line treatment. Nab-paclitaxel combined with anti-PD-1 inhibitor tended to produce better clinical benefit for the first-line treatment, especially for patients with acral melanoma. In addition, the tyrosine kinase inhibitor (TKI) combined with anti-PD-1 inhibitor also seemed to provide longer duration of response (DOR) for some patients. But combined therapy did not prolong the overall survival (OS) of NRAS-mutant patients. The combined therapy was well tolerated. Most adverse events were moderate and controllable. CONCLUSION: In conclusion, PD-1 inhibitor-based combined therapy increased clinical benefit for advanced patients with NRAS-mutant melanoma.

Ag Nanoparticle-Thiolated Chitosan Composite Coating Reinforced by Ag-S Covalent Bonds with Excellent Electromagnetic Interference Shielding and Joule Heating Performances.

Conductive composite coatings are an important element in flexible electronics research and are widely used in energy transformation, artificial intelligence, and electronic skins. However, the comparatively low electrical conductivity limits their performance in many specific applications, such as electromagnetic interference (EMI) shielding and Joule heating devices. Therefore, the preparation of ultrahigh-electrical conductivity composite coatings with good flexibility and durability remains a great challenge. Herein, we fabricated multifunctional conductive composite coatings based on thiolated chitosan (TCS) and Ag nanoparticles (AgNPs) by an eco-friendly drop-coating method. The three-dimensional conductive network constructed by thermal sintering imparted the coating with an ultrahigh electrical conductivity of up to 67079.4 S/m. Moreover, the coating reinforced by Ag-S covalent bonding exhibits good stability, including heat resistance, chemical resistance, and mechanical stability. In addition, based on the ultrahigh electrical conductivity, the coating exhibits superior EMI shielding effectiveness and Joule heating capability. With 30 wt % of AgNPs in the coating, the EMI shielding effectiveness of the coating reaches 70.2 dB, far exceeding commercial standards. Additionally, the coating can quickly reach a saturation temperature (Ts) of 195.9 °C at a safe drive voltage of 3 V. These excellent performances demonstrate that the robust and flexible highly conductive composite coatings prepared by this method have attractive potential for EMI shielding and thermal management applications as well as in wearable electronics.

Selective Sensing of Volatile Organic Compounds Using an Electrostatically Formed Nanowire Sensor Based on Automatic Machine Learning.

With the development of Internet of Things technology, various sensors are under intense development. Electrostatically formed nanowire (EFN) gas sensors are multigate Si sensors based on CMOS technology and have the unique advantages of ultralow power consumption and very large-scale integration (VLSI) compatibility for mass production. In order to achieve selectivity, machine learning is required to accurately identify the detected gas. In this work, we introduce automatic learning technology, by which the common algorithms are sorted and applied to the EFN gas sensor. The advantages and disadvantages of the top four tree-based model algorithms are discussed, and the unilateral training models are ensembled to further improve the accuracy of the algorithm. The analyses of two groups of experiments show that the CatBoost algorithm has the highest evaluation index. In addition, the feature importance of the classification is analyzed from the physical meaning of electrostatically formed nanowire dimensions, paving the way for model fusion and mechanism exploration.

A compact gas chromatography platform for detection of multicomponent volatile organic compounds biomarkers.

Some human exhaled volatile organic compounds (VOCs) can be employed to diagnose related human endogenous diseases as characteristic biomarkers, which is expected to be applied to rapid screening and grading because of their non-invasive and cost-effective advantages. In this study, we developed a compact gas chromatography (GC) platform mainly composed of an integrated silicon-based micro-column chip using micro-electromechanical system techniques and a miniaturized metal oxide semiconductor gas detector. In addition, the sampling/switching valve with related components and embedded microcontrollers was used for airflow control. The fabricated system selectively detected the five VOCs (pentane, acetone, toluene, octane, and decane) considered the typical endogenous disease biomarkers. In the experiments, the functional parameters of the system were investigated, and the optimum temperature conditions of the system for separation were determined. The results show that the system can successfully test the studied five VOCs as low as 1 ppm. In addition, the influence of interfering gas (carbon dioxide and ammonia) on the system for the VOC mixture is also investigated. Moreover, to prove the possibility of breath analysis of the fabricated system, the detection performance of isoprene and acetone at the ppb level is studied. Then, the concentration changes of the isoprene at the ppb concentration for human breath are successfully detected in the system. Therefore, we believe that the prepared compact GC system has potential applications in the human endogenous disease diagnosis for the VOC biomarkers.

Next-generation sequencing in advanced Chinese melanoma reveals therapeutic targets and prognostic biomarkers for immunotherapy.

Limited studies have interrogated the genomic landscape of Chinese melanoma in which acral and mucosal melanoma are the mainstay. In this study, we carried out a retrospective analysis on 81 Chinese melanoma patients (15 acral, 25 mucosal and 41 cutaneous melanoma). With the identification of 1114 mutations spanning 248 genes, we summarized that the mutation spectrum varied significantly by subtypes. Acral melanoma and mucosal melanoma had significantly more CNVs. MYC amplification was one of the most commonly detected CNVs, other frequent CNVs in mucosal melanoma included NBN and KDR, which were associated with the poor survival of melanoma patients. A generally low TMB, with a median of only 5.1 mut/Mb, was observed in three groups including cutaneous melanoma. Additionally, over 50% variants in DNA damage repair pathway were detected in all three subtypes, most of which were HRD related genes. Patients with alterations of HRD related genes had a longer survival time after immunotherapy. This study revealed a molecular profiling of Chinese patients with advanced melanoma, and proposed the high variant rate in DDR pathway as a biomarker of immunotherapy, which might provide therapeutic targets and guidance in making clinical decision for different Chinese melanoma.

Piezoelectric-AlN resonators at two-dimensional flexural modes for the density and viscosity decoupled determination of liquids.

A micromachined resonator immersed in liquid provides valuable resonance parameters for determining the fluidic parameters. However, the liquid operating environment poses a challenge to maintaining a fine sensing performance, particularly through electrical characterization. This paper presents a piezoelectric micromachined cantilever with a stepped shape for liquid monitoring purposes. Multiple modes of the proposed cantilever are available with full electrical characterization for realizing self-actuated and self-sensing capabilities. The focus is on higher flexural resonances, which nonconventionally feature two-dimensional vibration modes. Modal analyses are conducted for the developed cantilever under flexural vibrations at different orders. Modeling explains not only the basic length-dominant mode but also higher modes that simultaneously depend on the length and width of the cantilever. This study determines that the analytical predictions for resonant frequency in liquid media exhibit good agreement with the experimental results. Furthermore, the experiments on cantilever resonators are performed in various test liquids, demonstrating that higher-order flexural modes allow for the decoupled measurements of density and viscosity. The measurement differences achieve 0.39% in density and 3.50% in viscosity, and the frequency instability is below 0.05‰. On the basis of these results, design guidelines for piezoelectric higher-mode resonators are proposed for liquid sensing.

Efficacy and safety of anti-PD-1 inhibitor combined with nab-paclitaxel in Chinese patients with refractory melanoma.

PURPOSE: This retrospective study aimed to evaluate the combined effect of anti-PD-1 inhibitor and nanoparticle albumin-bound (nab)-paclitaxel for refractory melanoma among Chinese patients. METHODS: Data from January 2018 to March 2021 were retrospectively collected and analyzed. Sixty-four patients were eligible for analysis from a single Chinese cancer center. RESULTS: The median follow-up was 16.0 months at data cutoff. The objective response rate (ORR) was 29.7%, and the disease control rate (DCR) was 67.2% in all patients. Treatment-naïve patients had significantly higher ORR than pretreated patients (42.9% vs 13.8%, p = 0.011). Cutaneous melanoma patients with NRAS gene mutation benefited more than non-mutated patients (DCR of 100% vs. 54.5%) (p = 0.030). The median progression-free survival (mPFS) of all patients was 5.2 months and the duration of response was 10.8 months. Median duration of disease control was 7.7 months. Prior treatment-naïve patients had significantly longer PFS than those who accepted prior treatments (7.2 vs. 5.1 months, p = 0.024). Patients with abnormally high LDH level had shorter mPFS (3.6 months vs. 6.6 months, p = 0.020). Median overall survival was not reached in this study. Most patients experienced adverse events (AEs), but only 17.2% of patients experienced grade 3 severe AEs. The most common AEs were alopecia (89.1%), neutropenia (18.8%), pruritus (15.6%), and arthralgia (14.1%). Some patients had immune related AEs (irAEs). No grade 4 or 5 AEs were observed. Patients with ≥ 3 AEs or with irAEs had longer mPFS (p < 0.05). CONCLUSION: Nab-paclitaxel combined with PD-1 antibody is a well-tolerated and effective regimen for Chinese patients with refractory melanoma.

HHLA2 predicts improved prognosis of anti-PD-1/PD-L1 immunotherapy in patients with melanoma.

Background: As a recognized highly immunogenic tumor, immune checkpoint blockades (ICB) have been widely used as a systemic treatment option for melanoma. However, only about half of treated patients could benefit from it in Caucasians, and only about 15% in Chinese melanoma patients. Robust predictive biomarkers are needed. HHLA2, a new-found member of B7 family, is generally expressed in kinds of tumors, such as melanoma. This study focuses on illustrating the prognostic value of HHLA2 in melanoma immunotherapy and its association with tumor-infiltrating lymphocytes. Methods: HHLA2 expression in pan-cancer and the association with prognosis and immune microenvironment were identified by analyzing gene expression profiles from TCGA database with selected bioinformatics tools and methods. Tumor tissues from 81 cases with advanced and unresectable melanoma were collected for detecting HHLA2 and CD8 levels by immunohistochemistry. Results: HHLA2 was found to be ubiquitously expressed in pan-cancer with high level and correlate with the prognosis of patients. Further comprehensive analysis from TCGA database demonstrated that the highly expressed HHLA2 was remarkably correlated with better prognosis, high infiltration status of various immune-active cells and immune activated pathways in skin cutaneous melanoma (SKCM). Moreover, immunohistochemistry (IHC) analyses of FFPE tissue from melanoma patients revealed that HHLA2 high expression was strongly related to improved response to ICB and indicated a longer progression-free survival (PFS) and overall survival (OS). Besides, HHLA2 expression was found to have a positive association with the density of CD8+ TILs. Conclusion: Our findings revealed that high expression of HHLA2 has important values in predicting the response to ICB and indicating improved PFS and OS in patients with advanced and unresectable melanoma, suggesting that HHLA2 may serve as a costimulatory ligand in melanoma, which renders it as an ideal biomarker for immunotherapy.

Safety and Tolerability of BRAF Inhibitor and BRAF Inhibitor-Based Combination Therapy in Chinese Patients With Advanced Melanoma: A Real World Study.

The toxicity spectrum between Chinese and Caucasian patients with melanoma who were treated with BRAF inhibitors (BRAFi) may differ. The purpose of the present study was to assess the safety and tolerability of BRAFi and BRAFi-based combination therapies [MEK inhibitors (MEKi) or anti-programmed death-1 (PD-1) antibody] in Chinese patients with BRAF V600E/K mutation-positive metastatic melanoma. We also investigated whether treatment-related adverse events (AEs) correlated with the prognosis. This retrospective study collected data from 43 patients with BRAF V600E/K mutation-positive metastatic melanoma from a single Chinese cancer center. Of the 43 patients, 12 patients received BRAFi monotherapy, 12 patients received BRAFi+MEKi, and 19 patients received BRAFi combined with the anti-PD-1 antibody. The median follow-up time was 19 months. In the BRAFi group, the most common AEs were rashes, palmoplantar erythrodysesthesia, and arthralgia. Four out of 12 (30%) patients experienced grade 3-4 treatment-related AEs. All grades of AEs in the BRAFi+MEKi group were similar to the BRAFi group, except for higher pyrexia (58.3%) and fewer cutaneous AEs. Three out of 12 (25%) patients experienced grade 3-4 AEs, especially pyrexia (16.7%). In the BRAFi+anti-PD-1 antibody group, AEs were similar to the BRAFi group, except for an increased aminotransferase level (36.8%), increased bilirubin (31.6%), and hypothyroidism (15.8%). Eleven out of 19 (57.9%) patients experienced grade 3-4 AEs and four out of 19 (21%) patients discontinued the therapy due to AEs. Treatment-related hepatotoxicity (trHE), defined as an increase in either alanine aminotransferase (ALT), aspartate transaminase (AST), or bilirubin levels, was the only AE identified as a significant poor-prognosis indicator in this study. The median progression-free survival of patients with trHE (41.9%) was 8 months, whereas it was 18 months for those without trHE [p = 0.046, hazard ratio (HR) = 2.116]. Moreover, this association was independent of medication regimens (p = 0.014, HR = 2.971). The overall response rate of patients with trHE was significantly lower than those without trHE (44.4 vs. 60.0%, p = 0.024), and we observed a similar trend in patients treated with BRAFi, BRAFi+MEKi, and BRAFi+anti-PD-1 antibody. In conclusion, BRAFi and BRAFi-based combination therapies were tolerable with reversible AEs in Chinese patients with melanoma. The trHE in patients receiving BRAFi and BRAFi-based regimens might indicate a poor therapy-related prognosis.

Effects of strain on thermal conductivity of silicon dioxide thin films using test method based on 3-ω technique and uniaxial strain setup.

We propose a test method to study the effects of strain on the thermal conductivity of thin films. First, a strain setup was designed to apply stress to a thin film, and a test system was built to measure its thermal conductivity by combining the strain setup with the 3-ω method. The strain setup can apply stress to the specimen by adjusting load weights, while the strain of a thin film was obtained by measuring the applied stress with a force sensor. Second, the effects of strain on the resistance and temperature coefficients of a metal thin film were studied using the strain setup and the four-wire resistance measurement method; the results show that the resistance and temperature coefficients of metal thin films decrease with strain. Finally, the effects of strain on the thermal conductivity of a silicon dioxide thin film and silicon substrate were studied using the proposed method and test system. As the strain increased from 0% to 0.072%, the thermal conductivity of the 300-nm thick silicon dioxide thin film decreased from 0.907 W/(m K) to 0.817 W/(m K). The thermal conductivity of the 0.5-mm thick silicon substrate fluctuated in the range of 130.6 W/(m K) to 118.8 W/(m K) and then tended to stabilize around 126.4 W/(m K).

Micro-fabricated packed metal gas preconcentrator for enhanced monitoring of ultralow concentration of isoprene.

A novel non-silicon-based micro-preconcentration device, as a pretreatment component in a portable gas chromatography system, was developed for the preconcentration one of the trace volatile organic compounds (VOCs) in the exhaled gases, which is one typical biomarker for the chronic liver disease (CLD). The device was designed as an array of manifold-shaped rectangular metal micro-channels with flat dimensions of 16 mm × 12.6 mm and the internal empty volume is 14.4 µL on the copper substrate. Instead of the non-silicon fabrication process, the traditional laser etching technology (LET) was optimized to etch micro-channels, and vacuum diffusion welding (VDW) was applied to form internal channels. The fabricated chip was filled with Carbopack X adsorbent. In the testing, the metal gas preconcentrator (MGP) was installed in a commercial GC (gas chromatography) and nitrogen was used as carrier gas and desorbed gas. With the MPG, up to 352 of concentration factor can be achieved for 10 ppb isoprene. The developed MGP, which has advantages of high strength, low cost, good thermal conductivities, can potentially be used for non-invasive screening of advanced liver fibrosis by monitoring isoprene concentrations in exhaled breath.

Temperature compensation in fluid density measurement using micro-electromechanical resonant sensor.

In order to improve the measuring accuracy of micro-electromechanical system (MEMS) resonant sensor with micro-cantilever structure to measure fluid density, a temperature compensation method is presented. The elastic modulus of the micro-cantilever is calculated considering its temperature coefficient so that the working equation to measure fluid density is obtained with decreasing temperature disturbance on the measuring accuracy. The simulations and experimental measurements of several fluids with different densities were carried out by the MEMS micro-cantilever resonant sensor under different temperatures. The simulation analyses showed that the fluid densities measured by using the proposed resonant density sensor with temperature compensation were more fitted with the reference density values than those without temperature compensation. The experimental results showed that both the measuring accuracy and stability of the MEMS micro-cantilever resonant sensor in fluid density measurement were increased more than twice based on the temperature compensation method. Therefore, the proposed temperature compensation method is important to improve the measuring precision and stability of the MEMS micro-cantilever resonant sensor in fluid density detection fields.