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Breath ammonia is an important biomarker linked to liver malfunction. Acetone is the most abundant compound in the breath, acts as major interference for selective detection of ammonia gas. Here, a novel method based on viscosity modulation of the silicone oil absorbent is reported for selectivity improvement of ammonia over acetone gas. ATD-GC-MS and T201 ammonia analyzer are used to measure the absorption of acetone and ammonia respectively into the silicone oil. The absorption of ammonia and acetone gas is measured in different absorbent viscosities at a constant flow rate (50 cc min−1). Absorption results of ammonia are 7.37%, 16.3%, and 17.1% and acetone absorption results are 35%, 68%, and 78% respectively into 500 cSt, 100 cSt, and 20 cSt viscous silicone oil at room temperature. More bubbles of smaller diameter are formed at a lower viscosity, increases the contact time of the gas with absorbent. Consequently, the absorption of acetone into silicone oil at lower viscosity increases as compared to ammonia. The absorption of acetone is about 4.6-fold higher than the ammonia. Hence, it proves to be an effective technique for enhancing selectivity. This novel concept can be incorporated with any sensor for portable breath ammonia sensing in the detection of liver dysfunction.

A 43-μm-thick Si(111) substrate was obtained using the stress-induced lift-off method with a screen-printed metal paste layer as the stress-generation layer. The reflection of the metal-removed side of the Si(111) substrate was lower than that of the exfoliated side because of high surface roughness resulting from the reaction between the metal paste and the silicon substrate at 700◦C. After aggressive etching with an alkaline solution for the peeled silicon substrate, the efficiency of the heterojunction silicon solar cell was improved from 0.87% to 12%. © The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.0171508jss] All rights reserved.

This study proposes a promising silicon (Si) solar cell structure for reducing the potential induced degradation (PID) of crystalline Si solar cells. Phosphorous silicate glass (PSG) layers were carefully designed on an emitter layer, and the thickness of these layers (dPSG) was controlled by adjusting the diffusion temperature and time. The results show that the power loss remarkably decreased from 31% (dPSG = 0 nm) to 11% (dPSG = 22.3 nm) and further decreased to less than 5% after a 48-h PID test when dPSG was higher than 23.3 nm. No additional process or equipment was required for producing this effective and low-cost solar cell. © The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any

The detection of Volatile Organic Compounds (VOCs) biomarkers from the exhaled breath has opened the new techniques for medical diagnostics because of its noninvasive and inexpensive way of disease detection. Exhaled breath contains more than 1840 VOCs 1 which concentration may vary in ppb or in ppt range. The signature of some VOCs present in breath abruptly change with the specific disease, called biomarkers. Ammonia is an important biomarker for liver disease 2. There are many conventional techniques to detect ammonia in sub-ppm range including, proton transfer reaction mass spectrometry (PTR-MS), selected ion flow tube coupled mass spectrometry (SIFT-MS) 3, but these instruments are bulky and very costly. Metal Oxide (MOS) based gas sensors are very promising sensors for detection of breath biomarkers, but it also has a disadvantage of high operation temperature (more than 300ºC). Extensive attention has been paid recently to the indium nitride (InN) epitaxial layers and devices for gas sensing application because of its exceptional electronic properties, including excellent electron mobility, high electron density and comparatively low operation temperature ~200ºC. Moreover, an unusual phenomenon of strong electron accumulation at the surface of InN makes it highly sensitive gas sensor for VOCs detection 4. In this work, two InN based gas sensors of different thickness of the sensing film T1 (40nm) and T2 (60nm) are used respectively, for gas sensing. When the various concentration (0.3ppm, 0.5ppm, 1 ppm and 2ppm) of NH3 gas are exposed on the sensors, the current response is obtained at different thickness shown in (Figure 1a and 1b) respectively. The current variation response of 2 ppm NH3 gas on T1 is approx. 10 fold higher than T2 as shown in (Figure 1c). The current variation response for 0.5ppm on T1 is 0.04% while T2 showed negligible response as shown in (Figure 1d). The change at the surface of InN epilayer will be more significance on the total conductivity of thin layer as compare to thick layer 5. Hence, the lower thickness of the InN epilayer has higher response as compare to higher thickness. Therefore, lower thickness (40 nm) is suitable for diagnosis of liver malfunction. References B. de Lacy Costello, A. Amann, H. Al-Kateb, C. Flynn, W. Filipiak, T. Khalid, D. Osborne, and N. M. Ratcliffe, Journal of breath research, 8 (1), 014001 (2014). A. Kundra, A. Jain, A. Banga, G. Bajaj, and P. Kar, Clinical biochemistry, 38 (8), 696-699 (2005). S. T. Krishnan, J. P. Devadhasan, and S. Kim, Analytical and bioanalytical chemistry, 409 (1), 21-31 (2017). S. Rai, K.-W. Kao, S. Gwo, A. Agarwal, W. Lin, and J. Yeh, Sensors, 18 (11), 3887 (2018). H. Lu, W. J. Schaff, and L. F. Eastman, Journal of applied physics, 96 (6), 3577-3579 (2004). Figure 1: (a) current response at T1 (40 nm thickness), (b) current response at T2 (60 nm thickness), (c) current variation response at 2 ppm NH3 gas at T1 and T2, (d) current variation response at 0.5 ppm NH3 gas at T1 and T2. Figure 1

The gas sensor based on platinum-catalyzed ultrathin indium nitride (Pt-InN) was used to detect liver disease by sub-ppm ammonia (NH3) concentration variation in an ambient environment simulating exhaled human breath. Because the InN with strong surface electron accumulation extensively enhanced sensitivity, the NH3 gas sensor minimum detection limit is 0.2 ppm. Meanwhile, the sensor enables to distinguish slight deviation in NH3 concentration between 0.2 and 0.8 ppm that brings simple diagnosis of liver disease for portable and homecare clinical applications. Liver cancer is first of the top ten causes of death in Asia. Abnormal concentrations of the breath volatile organic compounds (VOCs) are reported to correlate with unhealthy/injurious body/organ conditions; for instance, ammonia (NH3) gas for renal and liver disease. Therefore, the detection of ammonia concentration in exhaled breath more important. In this study, an indium nitride (InN) gas sensor of 10 nm in thickness has achieved detection limit of 0.2 ppm ammonia. The sensor has a size of 1 mm by 2.5 mm, while its sensing area is 0.25 mm by 2 mm and deposited with a 10 nm thick Pt film on the sensing window to investigate the effect of catalyst on ammonia gas detection, shown in Fig 1. The ultrathin InN epilayer extensively enhances sensing sensitivity due to its strong electron accumulation on roughly 5–10 nm deep layers from the surface. Sensitivity is expected to be much better due to the natural electronic characteristics of as-grown InN films, including a narrow band gap, excellent electron transport characteristics (mobility > 1,000 cm2·V·s), a background high electron density (typically in excess of 1 × 1018 cm-3), and the unusual phenomenon of strong surface electron (charge) accumulation (1.57 × 1013 cm- 2) for the InN films grown on AlN film on a buffer layer . We proposing the miniaturized prototype, and packaging the ammonia gas sensor system (Including: Pt-InN sensor chip, heater, K-type thermocouple) on the 8 pin dual in-line package (DIP) for the portable human breath liver disease physiological detection application, shown in Fig 2. The current variation (DI) of a Pt-InN ammonia sensor under exposure to various ammonia concentrations from 0.2 ppm to 0.8 ppm in synthetic air at 200 °C is depicted in Fig 3. The experiments were repeatedly performed while the ammonia gas was turned on for 5 minute and off (i.e., in pure synthetic air) for another 5 minute at various ammonia concentrations. The current went up as ammonia concentration increased; such current increment was induced by the reduction of pre-adsorbed oxygen atoms. When ammonia molecules are introduced to the sensing system, the hydrogen atoms on dissociated ammonia molecules react with pre-adsorbed oxygen atoms, reducing the effects of surface depletion. Platinum as catalyst can increase output current signals as well as reduce response in comparison with Pt-InN, indicating that such an ammonia concentration can be analyzed in air. The dynamic responses of the Pt-InN sensor indeed demonstrate the great ability to sense ammonia gas at the sub-ppm level, and promising device for the realization of non-invasive ammonia sensing to detect ammonia in exhaled breath as a marker for liver disease. Figure 1

Hydrogen peroxide is a metabolic by-product and a kind of stable reactive oxygen species (ROS). When the ROS levels increase, it may causes several harmful effects of ROS on the cell structure, such as damage of DNA and protein oxidation, and this is known as oxidative stress. The oxidative stress is also the important clinical indicators of cause of aging, Alzheimer disease, and kidney diseases. Now the common test method of oxidative stress is Enzyme-linked immunosorbent assay (ELISA). ELISA needs color giving dyes, complicated preparation of sample, and optical system, so it is very expensive and inconvenient. In our study, we present a high sensitivity hydrogen peroxide sensor with ultra-low detection limit. The sensor can directly test the sample and only need very small amount of sample. And because of the simple structural design and fabrication, the sensor can be used as a cheap, efficient, and portable sensor system. In the future, the novel hydrogen peroxide sensor has various applications in studying oxidative stress and detecting reactive oxygen species for cells. Furthermore, we can combine the PANI sensor with different enzymes to fabricate other highly sensitive sensors to detect diverse materials, such as glucose, lactic acid and cholesterin. In our study, the PANI layer and gold electrodes were deposited on silicon nitride substrate, and the PANI was applied to fabricate a thin film between two electrodes. Then the PANI layer was sultonated by propane sultone and modified with HRP. During the measurement, the sensor was operated at 100mV and different concentrations of hydrogen peroxide citrate buffer solutions (pH=5.4) were dropped on it. The current change was measured when the hydrogen peroxide reacted with the HRP Immobilized PANI thin film. We tested the hydrogen peroxide solution from 0.1 nm to 1mM. The HRP-modified resistive sensors based on n-alkylated polyaniline(PANI) detect hydrogen peroxide in solution with very high sensitivity, ultra-low limit, and short response time. The sensitivity is higher than that of other sensing methods, such as electrochemical sensors or transistor sensors. The detection limit of PANI sensor is 0.7 nM (Figure 1. a, b). It is three orders smaller than that of other common methods with detection limit around 1 μM. To the best of our knowledge, it is the lowest detection limit that has ever been reported. And We combine the hydrogen peroxide sensor with glucose oxidase to build up the glucose sensor. In summary, the hydrogen peroxide sensor can provide a more exact hydrogen peroxide concentration and quick detection. The simple process for the sensor fabrication also allows the sensor to be cheap, disposable and combinable with other sensors to build up sensing system. This work was partially supported by National Science Council grant (No.99B20495A & 101-2221-E-007-102-MY3) and by the research grant (100N2049E1) at National Tsing Hua University.

Hydrogen peroxide attracts a great interest due to its important role in food, pharmaceutical, and clinical applications. Hydrogen peroxide is also a by-product in many enzyme catalytic reactions, such as glucose oxidase, lactate oxidase, cholesterol oxidase, alcohol oxidase, urate oxidase, aldehyde oxidase, and oxalate oxidase, which are implemented to detect glucose, lactic acid, cholesterol, ethanol, urea, formaldehyde, and oxalate, respectively. These biomolecules are significant markers in many biologically metabolic reactions. In our study, we present a cholesterol sensor based on a high sensitivity hydrogen peroxide sensor with ultra-low detection limit. The sensor can directly test the sample and only need very small amount of sample. And because of the simple structural design and fabrication, the sensor can be used as a cheap, efficient, and portable sensor system. The HRP-modified resistive sensors based on n-alkylated polyaniline(PANI) detect hydrogen peroxide in solution with very high sensitivity, ultra-low limit, and short response time. The sensitivity is higher than that of other sensing methods, such as electrochemical sensors or transistor sensors. The detection limit of PANI sensor is 0.7 nM. It is three orders smaller than that of other common methods with detection limit around 1 μM. To the best of our knowledge, it is the lowest detection limit that has ever been reported. And we combine the hydrogen peroxide sensor with cholesterol oxidase to build up the cholesterol sensor. In our study, the PANI layer and gold electrodes were deposited on silicon nitride substrate, and the PANI was applied to fabricate a thin film between two electrodes. Then the PANI layer was sultonated by propane sultone and modified with HRP. After that, the device was combined with dialysis membrane which was modified with cholesterol oxidase. During the measurement, the sensor was operated at 100mV and different concentrations of cholesterol PBS solutions (pH=7.0) were dropped on it. The cholesterol reacted with the cholesterol oxidase and created hydrogen peroxide on the PANI thin film (Figure 1). The current change was measured when the hydrogen peroxide reacted with the HRP immobilized PANI thin film. According to regular cholesterol level in human blood, we tested the cholesterol solution from 100 mg/dl to 400 mg/dl ,and we get a very good linear result (Figure 2). In summary, the cholesterol sensor can provide a more exact cholesterol concentration detection. The simple process for the sensor fabrication also allows the sensor to be cheap, disposable and combinable with other sensors to build up sensing system. This work was partially supported by National Science Council grant (No.99B20495A & 101-2221-E-007-102-MY3) and by the research grant (100N2049E1) at National Tsing Hua University.