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This work proposes a sensitive low-temperature sensor based on the refractive index (RI) method. It uses a one-dimensional (1D) photonic crystal (PC) structure. The proposed sensor design consists of a bilayer stack of dielectric and superconductor materials. YaBa₂Cu₃O₇ is the superconductor utilized in this case, and we consider air to be the dielectric material. The RI of air doesn’t change much with the temperature, especially compared to the superconductor material. YaBa₂Cu₃O₇ is a superconductor that is ideal for temperature sensing applications because of its temperature-dependent RI. The sensing temperature range for the proposed sensor is 35–70K. The crucial structural factors have been precisely adjusted to increase sensing performance. Based on our knowledge, this is done to increase the sensor’s efficiency to levels that are higher than anything previously reported in the literature. Results show that the designed structure achieves an impressive RI sensitivity of 821.53nm/RIU and a temperature sensitivity of 3nm/K. This sensor could be very useful for medical applications for the detection of low temperatures.

Bio-sensing sensitivity of a spectrally selective nanoparticle based ultraviolet (UV) photodetector is characterized in comparison to a silicon photodiode and a photomultiplier tube (PMT). The nanoparticle based photodetector is comprised of poly-vinyl alcohol (PVA) coated zinc-oxide (ZnO) nanoparticles deposited on an aluminum-gallium-nitride (AlGaN) epitaxially grown substrate. The sensitivity was determined by measuring the fluorescence intensity of the native fluorophore, tryptophan, in Escherichia coli (E-coli, ATCC-25922) cells. Tryptophan intrinsically fluoresces with a peak at 340 nm under 280 nm UV light illumination. It is shown that this detector can sense the concentration of E-coli to 2.5 × 10⁸ cfu/mL while the silicon photodiode cannot detect the intrinsic fluorescence at all. Nevertheless, the PMT outperformed the ZnO nanoparticle-AlGaN substrate based photodetector with the ability to sense E-coli concentrations to 3.91 × 10⁶ cfu/mL. However, because PMT based systems are commonly limited by high dark current, susceptible to environmental changes, sensitive to ambient light, are not spectrally selective and have high power consumption, biological detection systems comprised of these ZnO nanoparticle-AlGaN substrate based photodetectors can be more effective for near real time characterization of potential bacterial contamination.

This paper presents a low-power low-noise instrumentation amplifier (IA) for bio-potential recording. The proposed IA is based on a novel Gm-RSC structure, whose gain is determined by the transconductance (Gm) and the equivalent resistance ($R$) of the switched-capacitor (SC) load. The transconductance amplifier stage is based on the current-reuse telescope topology to achieve low noise at low-power dissipation. A resistor-controlled oscillator is designed to generate desirable operational frequency for SC load and to continuously tune the mid-band gain of the IA for different biomedical applications. Measurement results show that the input referred noise of the proposed IA is about 1.27$\mu$V_RMS ($\mathrm{\text{BW}}=150$Hz) and the noise efficiency factor is 3.3. The range of tunable gain is from 28 to 40dB. The common mode rejection ratio and power supply rejection ratio at 50Hz are 72 and 78dB, respectively. The IA consumes only 660nA current at 1.2V supply and the active area of the IA is only 0.035mm².