Solid-State Microfluidics with Integrated Thin-Film Acoustic Sensors.

For point-of-care applications, integrating sensors into a microfluidic chip is a nontrivial task because conventional detection modules are bulky and microfluidic chips are small in size and their fabrication processes are not compatible. In this work, a solid-state microfluidic chip with on-chip acoustic sensors using standard thin-film technologies is introduced. The integrated chip is essentially a stack of thin films on silicon substrate, featuring compact size, electrical input (fluid control), and electrical output (sensor read-out). These features all contribute to portability. In addition, by virtue of processing discrete microdroplets, the chip provides a solution to the performance degradation bottleneck of acoustic sensors in liquid-phase sensing. Label-free immunoassays in serum are carried out, and the viability of the chip is further demonstrated by result comparison with commercial ELISA in prostate-specific antigen sensing experiments. The solid-state chip is believed to fit specific applications in personalized diagnostics and other relevant clinical settings where instrument portability matters.