Light-triggered, contactless microfluidic actuation via photothermal gas generation for molecular diagnostics

The advancement of microfluidic technologies has enabled more rapid analysis and reduced cost per reaction through system miniaturization, demonstrating great potential in diagnostics, particularly in point-of-care testing (POCT). However, precise fluid control at the microscale still relies on bulky and complex pumping systems, which limits their POC applications. Moreover, direct physical connections between external pumping elements and microfluidic chips lead to device failure. Therefore, the development of contactless microfluidic actuation strategies is essential for developing portable and user-friendly POC microfluidic systems. Among these approaches, light-triggered actuation offers a promising solution. Photothermal materials can efficiently convert light into heat, translating optical energy into mechanical force. In this study, we present a light-triggered microfluidic actuation system based on gas generation induced by photothermal heating for POCT applications. Polydopamine nanoparticles, known for their excellent biocompatibility and high photothermal efficiency, were dispersed in an organic compound for long-term colloidal stability and reliable thermal performance. Upon light irradiation, photothermal microheaters initiate a rapid generation of CO₂, which drives fluid actuation in a controllable manner. To enhance their applicability in POCT, FTA cards were integrated to extract and purify nucleic acids prior to loop-mediated isothermal amplification. This process was fully automated through a programmed operation protocol and successful detection of Acinetobacter baumannii was achieved. This work provides a scalable and versatile microfluidic actuation strategy, offering enhanced portability and user-friendliness for POCT applications.