Cooling represents a significant sector of energy consumption.¹ It is the most significant driver of peak electricity demand as well as considerable end use of energy globally.² The global energy consumption can be reduced by adopting a cooling strategy that can cool without any electrical input, which is also known as passive cooling technique. The cooling can be achieved if one is able to reach and maintain a temperature below ambient temperature. Radiative cooling, as a passive radiative cooling scheme, does not require any external active devices, such as fans, air conditioners, or thermoelectric.^{3 – 5} It works on the principle that the atmosphere is almost transparent between 8 and $13\mu \mathrm{m}$ (also known as ‘‘sky window”). Thus, utilizing outer space as a heat sink by allowing the emission of thermal radiation from surface to the universe.^6,7

This review manuscript presents Thin-Film Transistors (TFTs) for various highly sensitive biosensing applications. A low-cost, highly sensitive, early-stage diagnostic bio-sensing devices are vital for different biomedical and biological applications. Nanotechnology-based biosensor devices such as bioFET, thin-film transistor (TFT), etc. are used to overcome the problems of conventional health diagnostic approaches. Among them, TFT based biosensors have gained a lot of attention owing to high sensitivity, high-scalability, low power consumption, rapid electrical detection, low-cost mass production, and direct electrical readouts. Further to improve the sensitivity of TFT bases biosensor, transparent materials are frequently used in current biosensing research fields and it is found that indium tin oxide (ITO) is most favorable for biosensing applications. Thus, the amalgamation of ITO on TFT paves the way with the existing CMOS technology for early-stage diagnostic of protein-related diseases such as coronary artery disease, ovarian cancer, and Alzheimer’s diseases.

In this paper, the thermal stability of a Bloch Surface Wave (BSW) assisted bio-photonic sensor is investigated. The structural analysis is carried out using the transfer matrix method (TMM). The design comprises a truncated one-dimensional photonic crystal (1D-PhC) structure along with a defective top layer. The structural parameters are optimized to excite a BSW at the top interface for an operating wavelength of 632.8 nm. The mode confinement is confirmed by using wavelength interrogation, angular interrogation and surface electric field profile. Further, the effect of thermal variation on BSW excitation angle and sensitivity is carried out. The analysis shows the average variations in excitation angle and sensitivity of about −0.00096 degree/$°\mathrm{C}$ and 0.01046 (degree/RIU)/$°\mathrm{C}$, respectively. Additionally, the analysis is also extended towards different lower wavelengths of 400 nm and 550 nm, which provides average variations in the excitation angles of about −0.0027 degree/$°\mathrm{C}$, and 0.0016 degree/$°\mathrm{C}$. This shows that the structural sensitivity response is more thermally stable at the lower wavelength range. Thus, showing its potential applications in designing thermally stable bio-photonic sensors.

In this paper, a 4-N,N-dimethylamino-4${}^{\prime }$-N${}^{\prime }$-methyl-stilbazolium tosylate (DAST) material assisted one-dimensional photonic-crystal-based (1D-PhC) tunable optical filter is presented. The design comprises a bilayer 1D-PhC structure having DAST as an electro-optic material. The device parameters are configured to filter out the 632.8 nm wavelength from the reflection spectrum. The analysis shows that by illuminating the device with poly-chromatic light at an incident angle of 45.07${}^{°}$, the filtered wavelength exhibits transmission maxima having FWHM of less than 1nm. The analytical results also demonstrate the post fabrication 60 nm electrical tuning of the filtered wavelength by using only ±5 V applied potential. The structure also exhibits a very stable filter response up to 40% variations in optical thickness. Thus, the proposed design possesses the advantage in terms of low voltage wavelength tuning, stable response, easy fabrication and integration capability in integrated circuits.