Design and Fabrication of an Enhanced Thermoresponsive PEG/Carbon Nanotube Microvalve for Efficient Flow Control in Microchannels

Abstract Microvalves are essential in microfluidic systems, as they regulate fluid flow direction and enable critical operational functions. This study focuses on designing and fabricating a phase change polymeric microvalve utilizing polyethylene glycol (PEG) combined with multiwall carbon nanotubes (MWCNT) to improve the response time. A microchip made from polydimethylsiloxane (PDMS) features a microchannel with a cross‐sectional area of 100 × 200 µm² where water is injected at flow rates between 10 and 100 mL min⁻¹. In addition, effective thermal regulation is attained by implementing a nickel–chromium wire plate heater, which is meticulously controlled by a sensor to guarantee precise temperature management. The results indicate that the fabricated microvalve exhibits remarkable operational limits, withstanding a maximum tolerable pressure of 182 mmHg in the closed state. It consistently achieves an average response time of ≈170 s under various temperature conditions, underscoring its efficiency and reliability for demanding applications. Notably, the incorporation of 0.1 wt.% MWCNTs in PEG successfully reduce the response time from 180 to 130 s at an operating temperature of 60 °C, demonstrating significant potential for developing faster actuators.