Wind-up precision pump for portable microfluidics

Abstract

Herein, a wind-up precision pump is proposed in which the pump is powered by the manual winding of a helical spring, similar to that in a mechanical watch. The unwinding of the wound helical spring provides a constant torque. The connecting gears at the spring convert the rotational movement of the spring into linear motion to generate a constant force for pushing a syringe. Incorporating the high-precision mechanism of a mechanical watch into the pump can generate precise, steady, and pulse-less flows over the range of 0.1 mL/h to 0.8 mL/h. The flow rate can be easily adjusted by changing the gear ratio, syringe diameter, and balance wheel moment of inertia. The wind-up pump can perform the same functions as a syringe pump, but is smaller, lightweight, and disposable, making it suitable for field-portable microfluidic applications. Thus, it is named precise, accurate, little microfluidic (PALM) pump. The utility of the PALM pump is demonstrated through the on-site fabrication of injectable radioactive hydrogel microparticles for local radiotherapy and monitoring of their anti-cancer effects on HeLa cells. The PALM pump can not only completely replace syringe pumps, but can also contribute greatly to the widespread use of microfluidic platforms.