Portable high-pressure pump system for HPLC combining pressurized gas and on-chip pressure regulation

Abstract

High-pressure pumps for microfluidic systems typically require high power and have large sizes, which hinder portability of otherwise miniaturized HPLC systems. To solve this, a battery-powered, pneumatic system for pressure-driven chromatography is presented. The system utilizes the stored energy in pressurized gas without consuming any of the gas. As the chromatography liquid flows, the gas in the pressure container expands and its pressure reduces. To compensate for this, a solution is presented with an on-chip microfluidic pressure regulator. The chip contains a microfluidic restrictor where fluid is heated by Joule heating to decrease viscosity, and thus reduce the pressure drop over the restrictor. An 18 V battery driven system with 50 ml N2 at 51 bar could provide a water flow rate of 55μl/min at 32 bar for 67 min with a mean power consumption of 0.2 W. With the regulating microfluidic chip, the pressure stability was 2 mbar, i.e., on pair with high-quality high-pressure syringe pumps. The required gas volume, and hence the total size, is scalable with the desired liquid volume, which makes it suitable for miniaturized systems.