Enhancing Microfluidic Chip Functionality via Thermal Gradient‐Driven Optofluidic Manipulation

Abstract Thermal gradient‐driven fluid motion, also known as thermal convection, is a common and significant phenomenon in nature. The utilization of localized thermal gradients to induce convection has emerged as a competitive approach in microfluidic chips. This technique enables the long‐distance transportation of substances under the influence of low‐power lasers. In this paper, an innovative optofluidic micro‐platform is presented that possesses a simple structure, easy operation, and excellent expandability. A UV nanosecond laser is utilized to create a high photothermal conversion region (HPCR) within the carbon nanotube‐doped PDMS substrate. Subsequently, the HPCR is subjected to irradiation for generating localized thermal gradients in the microfluidic chip. This resulted in Rayleigh–Bernard convection formation and facilitated long‐range transport and control of fluids and particles. Under low‐power laser irradiation, particles can be transported at speeds up to 0.18 mm s −1 . In addition, the optofluidic platform shows significant potential for a range of functionalities, including fluid mixing and material sorting. The methodology described here allows for the rapid integration of new functionalities into existing chips while maintaining cost effectiveness and efficiency. This technique holds great promise for expanding the use of microfluidic devices in diverse fields, including chemistry, health sciences, materials science, and biomedicine.