A role of integrated microheaters in a microfluidics based point-of-care-testing and beyond for healthcare applications

In recent times, microheaters have gained a vast range of attention due to their universal existence in most research domains such as healthcare, pharmaceutical, clinical, electrical, and mechanical applications. Especially, post-COVID-19 the significance of microheaters in the point-of-care-testing based microdevices has immensely increased and overlaid the way for the possibility of the development of microfluidic-based diagnostics tools for point-of-care applications. In microfluidics, temperature is a crucial aspect but occasionally disregarded parameter due to its non-uniform distribution and unstable heat regulation within the microchannels. Nevertheless, fluctuations in size, ramping rate, stability, and accuracy make them unsuitable for operating in isolated areas. Microarchitecture of heaters decreases power utilization, increases ramping rate, maintains uniform temperature distribution, executes rapid response, and improves temperature conductivity. The usual thickness of a microheater comes around 100 nm to 100 μm and provides precision control over a temperature range of up to >1000 °C. Because of the escalating demand for wearable biosensors, wearable electronics, and flexible materials, microheaters have transpired as an exigent and peremptory in most research areas. This review comprehensively discusses several different kinds of microheaters emphasizing design, material selection, optimization, and fabrication tools, that are predominantly used in microfluidic technology for POCT applications. Further, this also throws limelight on emerging technological trends and challenges in micro-electro-mechanical-systems (MEMS) based microheaters that can pave the way for developing advanced, rapid, reliable, and susceptible devices that are implemented in healthcare diagnostics, electrical, biomedical, and mechanical domains within microscale environment.