This letter examines a planar cholesteric cell ͑CLC͒ doped with two collocated laser dyes as a one-dimensional photonic crystal. Adding phototunable chiral material ͑AzoB͒ allows the CLC photonic crystal to be lased at the band edges of the photonic band gap with a tuning range of over 100 nm. Tuning is performed by irradiating the chiral AzoB material with UV light, causing the material to undergo trans-cis isomerization in the CLC film. The tuning range is the visible region from 563 to 667 nm. Moreover, the tuning is reversible.
Although the indirect calorimeter is a useful tool, its size and expense mean that it is seldom used in hospitals. Furthermore, its flow-through measurement technique dilutes respiratory variations, so they can only be detected with some form of high-precision instrumentation. This study employs MEMS techniques to develop an oxygen sensor as one part of a microscopic energy consumption measurement system, which measures respiration dynamics in a real time manner. The oxygen sensor comprises a polysilicon resistor and a Li-doped (2 wt%) tin-oxide sensing film attached to a thermally isolated silicon-nitride membrane. The power consumption of the sensor is less than 25 mW at an operating temperature of 150 degrees C. Furthermore, it measures oxygen concentrations between 25 and 85% with a linear output response. These characteristics render the proposed sensor suitable for use within a microscopic energy consumption measurement system in either hospital or homecare environments.
This study proposes a long period fiber grating (LPFG) with a zinc oxide (ZnO) nanoparticle layer for use as a carbon dioxide (CO 2) gas sensor. Inductively coupled plasma (ICP) etching, corona treatment, and electrostatic spraying were used to fabricate this ZnO nanoparticle-coated LPFG CO 2 gas sensor. Repeated gas sensor tests showed that, when a 15% CO 2 mixture was injected (0.2 L/min) into a closed chamber into which the sensor had been placed, the CO 2 gas was absorbed by the ZnO nanoparticle-coated LPFG sensor. In these tests, the transmission loss gradually decreased, and the maximum transmission loss was 2.039 dB. The concentration test results showed that as the concentration of CO 2 introduced into the chamber was increased, the rate of the transmission loss change was increased in direct proportion. In addition, the sensitivity was 0.0513 dB/%. The results confirm that this low-cost ZnO nanoparticle-coated LPFG gas sensor was successfully applied to the measurement of CO 2 gas. Therefore, the proposed ZnO nanoparticle-coated LPFG can be used to measure CO 2 gas.
Although the conventional indirect calorimeter is a valuable tool, its size and expense prohibits its widespread use in hospitals. Furthermore, its flow-through measurement technique dilutes the respiratory variations, and hence some form of high-precision detection instrumentation is required. These limitations may be overcome by combining MEMS with CMOS circuit design technology to develop an innovative SOC biochip as the basis of a miniaturized energy consumption measurement system. In order to measure the characteristics of the oxygen sensors which form one part of this system, this study develops an automated oxygen concentration control and measurement system. This system can simulate the miniscule respiratory variations of a premature infant and can subsequently establish a suitable oxygen concentration environment to ensure the infant's well being. The proposed system is capable of establishing environments with oxygen concentrations ranging from 5% to 100%, and can control the oxygen concentration to a resolution of 0.006%. The minimum time required to increase the oxygen concentration from 21% to 100% is approximately 5.6 seconds. The proposed system can also automatically measure the properties of the oxygen sensors, including their resistance characteristics at different oxygen concentrations, the relationship between their sensitivity and the oxygen concentration, and the influence of working temperature and humidity upon their sensitivity. The necessary measurement data is acquired locally and can then be transmitted to a remote PC via the Internet.
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