A Microfluidic Transistor for Liquid Signal Processing

Abstract

Abstract/SummaryMicrofluidics have enabled significant advances in molecular biology1–3, synthetic chemistry4,5, diagnostics6,7, and tissue engineering8. However, there has long been a critical need in the field to manipulate fluids and suspended matter with the precision, modularity, and scalability of electronic circuits9–11. Just as the electronic transistor enabled unprecedented advances in the control of electricity on an electronic chip, a microfluidic analogue to the transistor could enable improvements in the complex, scalable control of reagents, droplets, and single cells on an autonomous microfluidic chip. Prior works on creating a microfluidic analogue to the electronic transistor12–14could not replicate the transistor’s saturation behavior, which is crucial to perform analog amplification15and is fundamental to modern circuit design16. Here we exploit the fluidic phenomenon offlow-limitation17to develop a microfluidic element with flow-pressure characteristics completely analogous to the current-voltage characteristics of the electronic transistor. As this microfluidic transistor successfully replicates all of the key operating regimes of the electronic transistor (linear, cut-off and saturation), we are able to directly translate a variety of fundamental electronic circuit designs into the fluidic domain, including the amplifier, regulator, level shifter, logic gate, and latch. Finally, we demonstrate a “smart” particle dispenser that senses single suspended particles, performs liquid signal processing, and accordingly controls the movement of said particles in a purely fluidic system without electronics. By leveraging the vast repertoire of electronic circuit design, microfluidic transistor-based circuits are easy to integrate at scale, eliminate the need for external flow control, and enable uniquely complex liquid signal processing and single-particle manipulation for the next generation of chemical, biological, and clinical platforms.