Microfluidic switchboards with integrated inertial pumps

TL;DR

This paper presents a fully integrated microfluidic switchboard with inertial pumps that can route, mix, and control fluids without external power, using silicon/SU8 microfabrication and a matrix flow model.

Contribution

Introduction of a silicon-based microfluidic switchboard with integrated inertial pumps capable of complex fluid routing and operations without external power sources.

Findings

Demonstrated fluid routing, mixing, and valving in microfluidic networks.

Developed and validated a matrix formalism for flow description.

Achieved fully integrated, power-free microfluidic control.

Abstract

Arrays of H-shape microfluidic channels connecting two different fluidic reservoirs have been built with silicon/SU8 microfabrication technologies utilized in production of thermal inkjet printheads. The fluids are delivered to the channels via slots etched through the silicon wafer. Every H-shape channel comprises four thermal inkjet resistors, one in each of the four legs. The resistors vaporize water and generate drive bubbles that pump the fluids from the bulk reservoirs into and out of the channels. By varying relative frequencies of the four pumps, input fluids can be routed to any part of the network in any proportion. Several fluidic operations including dilution, mixing, dynamic valving, and routing have been demonstrated. Thus, a fully integrated microfluidic switchboard that does not require external sources of mechanical power has been achieved. A matrix formalism to describe flow in complex switchboards has been developed and tested.