UC Berkeley

Though microfluidic and BioMEMS devices have been active areas of research since the late 1990s, commercial success of diagnostic tools making use of these technologies has been limited, especially with regard to complex “micro-total analysis systems” with integrated fluid control and sample preparation. The incompatibility of current prototyping technology (PDMS soft lithography) used during the discovery phase with large-scale industrial production and the difficulty of integrating electronic sensing and fluid control with PDMS devices contribute to this problem by requiring substantial redesign of microfluidic devices from prototype to manufacturable product. Therefore, there is a need for a lab-scale prototyping method that is compatible with manufacturing-friendly materials and which allows for simple integration of electronic components.

I will describe such a method based on hot embossing of thermoplastics and propose modifications to this method which allow for simultaneous patterning of microfluidic channels and integration of electrodes with a variety of geometries. This method involves minimal specialized equipment and is similar in complexity to the fabrication of PDMS devices. Furthermore, I will describe applications of this manufacturing technology to impedance cytometry and electrolysis-driven pumping.

Efforts to increase the complexity and decrease the footprint of microfluidic devices also require novel strategies for on-chip sensing and actuation. To that end, I will also describe two strategies for such compact active devices. The first is a pump powered by chemical propellant and fabricated using high-resolution 3D printing, which has been applied to oral vaccine delivery. The second is an electrically-actuated magnetic particle sorter which makes use of the inverse magnetostrictive effect in a multiferroic heterostructure to achieve local control of particle motion without an external magnetic field.

Taken together, the work described in this dissertation is intended to advance the potential of integrated microfluidic systems to function without the requirement of an extensive external infrastructure including off-chip pumps and microscopes, and to ease the transition of microfluidic devices out of the lab by incorporating some design-for-manufacturing ideas into the early stages of the development of such devices.