Microfluidic Fredkin gate: A novel control unit for integrated microfluidic systems

Abstract

The need for efficient miniaturized control elements in integrated microfluidic systems and lab-on-chip devices has always been a challenge. This paper proposes the first-of-its-kind microfluidic-based Fredkin gate that mimics the functionality of Fredkin-gate in electronics. This reversible microfluidic gate is versatile and can be used to implement all binary functions on its fluidic inputs. We demonstrate the design and fabrication of the microfluidic Fredkin-gate. The proposed gate is fabricated over the PDMS elastomer, using a network of microfluidic channels and pressure-driven membrane microvalves based on standard soft-lithography processes. Then, we study the gate's performance under different inlet flow rates and control pressures. A threshold pressure of 20 kPa is obtained for an inlet flow rate of 3 ml/min, which is in good agreement with the simulation outcomes. Finally, we demonstrate the implementation of the basic logic gates (AND, OR, NOT) using the fabricated Fredkin-gate. The proposed nondissipative microfluidic gate provides a simple design, implementation, and integration into Multilayer Soft Lithography (MSL) microfluidics. It can operate as a repeatable on-chip control unit to run serial or parallel logic functions in large-scale integrated microfluidic devices for complex manipulations of fluid flow.