3D-printed liquid metal-based stretchable conductors and pressure sensors

Abstract

Microfluidic devices control fluids on the micrometer-scale and are commonly used for lab-on-chip applications, such as sensors, micropumps and biological analyzers. Commonly reported fabrication methods for achieving flexible microfluidic structures are labor-intensive, require many cumbersome steps, and have limited options for materials. This paper presents a rapid-manufacturing technique using a PolyJet 3D-printer for creating soft microfluidic substrates embedded with liquid metals to fabricate stretchable conductors and pressure sensors. By using this novel method, several spiral-shaped soft pressure sensors with multimaterial-based substrates are 3D-printed simultaneously in less than six minutes. Microfluidic channels with cross-sections ranging from 150 × 150 to 350 × 350 µm are successfully achieved in a soft substrate. This 3D-printing method allows fabrication of complex, enclosed channels without any photocurable support material, thus minimizing post-processing time. Simulation and experiments are conducted to characterize the quasi-static and dynamic properties of the fabricated pressure sensor. In particular, experimental results show that these 3D-printed microfluidic pressure sensors are robust, capable of withstanding high pressures up to 1 MPa.