TAILIEUCHUNG - Biosensors for Health Environment and Biosecurity Part 2

Tham khảo tài liệu 'biosensors for health environment and biosecurity part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | AlGaN GaN High Electron Mobility Transistor Based Sensors for Bio-Application 27 schematic of the system for collecting the EBC is illustrated in Figure 8. The AlGaN GaN HEMT sensor is directly mounted on the top of the Peltier unit HT 232 Kryotherm as also shown in Figure 7 which can be cooled to precise temperatures by applying known voltages and currents to the unit. During our measurements the hotter plate of the Peltier unit was kept at 21oC and the colder plate was kept at 7 oC by applying bias of V at A. The sensor takes less than 2 sec to reach thermal equilibrium with the Peltier unit. This allows the exhaled breath to immediately condense on the gate region of the HEMT sensor. Fig. 7. Optical image of sensor mounted on Peltier cooler. Prior to pH measurements of the EBC a Hewlett Packard soap film flow meter and a mass flow controller were used to calibrate the flow rate of exhaled breath. The HEMT sensors were also calibrated and exhibited a linear change in current between pH 3-10 of 37pA pH. Due to the difficulty to collect the EBC with different glucose concentration the samples for glucose concentration detection were prepare from glucose diluted in PBS or DI water. The HEMT sensors were not sensitive to switching of N2 gas but responded to applications of exhaled breath pulse inputs from a human test subject as shown at the top of Figure 9 top which shows the current of a Sc2C 3 capped HEMT sensor biased at for exposure to different flow rates of exhaled breath l min . The flow rates are directly proportional to the intensity exhalation. Deep breath provides a higher flow rate. A similar study was conducted with pure N2 to eliminate the flow rate effect on sensor sensitivity. The N2 did not cause any change of drain current but the increase of exhaled breath flow rate decreased the drain current proportionally from L min to a saturation value of 1 L min. For every tidal breath the beginning portion of the .

TỪ KHÓA LIÊN QUAN
Đã phát hiện trình chặn quảng cáo AdBlock
Trang web này phụ thuộc vào doanh thu từ số lần hiển thị quảng cáo để tồn tại. Vui lòng tắt trình chặn quảng cáo của bạn hoặc tạm dừng tính năng chặn quảng cáo cho trang web này.