On-Substrate Joule Effect Heating by Printed Micro-Heater for the Preparation of ZnO Semiconductor Thin Film

Positive and Negative Photoconductivity in Ir Nanofilm-Coated MoO3 Bias-Switching Photodetector

In this study, we delved into the influence of Ir nanofilm coating thickness on the optical and optoelectronic behavior of ultrathin MoO3 wafer-scale devices. Notably, the 4 nm Ir coating showed a negative Hall voltage and high carrier concentration of 1.524 × 1019 cm-3 with 0.19 nm roughness. Using the Kubelka-Munk model, we found that the bandgap decreased with increasing Ir thickness, consistent with Urbach tail energy suggesting a lower level of disorder. Regarding transient photocurrent behavior, all samples exhibited high stability under both dark and UV conditions. We also observed a positive photoconductivity at bias voltages of >0.5 V, while at 0 V bias voltage, the samples displayed a negative photoconductivity behavior. This unique aspect allowed us to explore self-powered negative photodetectors, showcasing fast response and recovery times of 0.36/0.42 s at 0 V. The intriguing negative photoresponse that we observed is linked to hole self-trapping/charge exciton and Joule heating effects.

Design and Fabrication Process Optimization of Silver-Based Inkjet-Printed Microheater

This paper examines the simulation, design, and fabrication of a nano-particle silver microheater. COMSOL Multiphysics is used to simulate the microheater of an area of 720 × 720 μm2. Different stages of the microheater fabrication process are discussed. The size of the cartridge used is 10 pL and the nozzle diameter was 50 μm. The drop spacing was chosen to be 45 μm after testing several different values. Controlled printing of Ag ink was reached by setting the tickle control frequency to 8 kHz and cartridge print height to 0.4 mm. The nozzle temperature was set at ambient temperature. The inkjet printed microheater is of same area and track and gap widths of 110 μm. The measured resistance of the microheater, 119 Ω, is approximately equal to the simulated resistance of 100 Ω. It was observed that the temperature at the center of the heater reaches up to 250 °C.

Microheater: material, design, fabrication, temperature control, and applications-a role in COVID-19

Heating plays a vital role in science, engineering, mining, and space, where heating can be achieved via electrical, induction, infrared, or microwave radiation. For fast switching and continuous applications, hotplate or Peltier elements can be employed. However, due to bulkiness, they are ineffective for portable applications or operation at remote locations. Miniaturization of heaters reduces power consumption and bulkiness, enhances the thermal response, and integrates with several sensors or microfluidic chips. The microheater has a thickness of ~ 100 nm to ~ 100 μm and offers a temperature range up to 1900℃ with precise control. In recent years, due to the escalating demand for flexible electronics, thin-film microheaters have emerged as an imperative research area. This review provides an overview of recent advancements in microheater as well as analyses different microheater designs, materials, fabrication, and temperature control. In addition, the applications of microheaters in gas sensing, biological, and electrical and mechanical sectors are emphasized. Moreover, the maximum temperature, voltage, power consumption, response time, and heating rate of each microheater are tabulated. Finally, we addressed the specific key considerations for designing and fabricating a microheater as well as the importance of microheater integration in COVID-19 diagnostic kits. This review thereby provides general guidelines to researchers to integrate microheater in micro-electromechanical systems (MEMS), which may pave the way for developing rapid and large-scale SARS-CoV-2 diagnostic kits in resource-constrained clinical or home-based environments.