Microfluidic devices involving single-phase operations, as well as those involving solid-gas and solid-liquid interactions, have been extensively studied both theoretically as well as experimentally. However, there are noticeably fewer published experimental results involving gas-liquid multiphase systems. The comparatively fewer number of published studies is not due to a lack of applicable unit operations within the chemical industry that would benefit from microfluidic technology, but rather due to the inherent challenges of constructing and operating a device capable of manipulating these two phases at length-scales in which surface tension forces dominate.

This presentation will describe a microfluidic device capable of a wide-range of unit operations involving gas-liquid multiphase flow, specifically those involving vapor-liquid equilibrium. Robustness of this device is achieved through careful design of the microcomponents, as well as via a computer-control scheme ensuring complete vapor-liquid flow control under a wide range of operating conditions. Although this device would be applicable to unit operations across widely diverse industries, examples in this specific presentation will focus on operations within the pharmaceutical industry traditionally performed as batch processes, now enabled as continuous-flow processes using the microfluidic device.

Specifically, the time-cycle consuming unit operation used extensively within the pharmaceutical industry known as a “solvent-switch” (a constant-volume batch distillation) will be demonstrated as a continuous-flow operation. Advantages of the microfluidic device in this specific example include the potential for reduced batch time-cycle, as well as increased product yield in cases where the molecule of interest is heat-sensitive (due to greatly reduced residence times at elevated temperatures). Examples of this microfluidic device with respect to other unit operations may also be presented.