Arrays of horizontally-oriented mini-reservoirs generate steady microfluidic flows for continuous perfusion cell culture and gradient generation

TLDR

Horizontal reservoirs maintain a constant pressure drop and produce flow rates proportional to height differences, and their compatibility with standard 96‑well pipettors makes the system broadly useful for high‑throughput microfluidic perfusion, migration, and drug‑testing assays. The study aims to demonstrate that arrays of horizontally‑oriented reservoirs can deliver liquids through microchannels at a constant flow rate over hours to days. The authors implemented a one‑inlet–one‑outlet system and an array of inlet reservoirs linked to a single outlet reservoir via microchannels to continuously perfuse cell culture media and generate multiple laminar streams. The simple, versatile pumping system produced smooth and step concentration gradients that facilitated testing colchicine’s impact on myoblasts.

Abstract

This paper describes the use of arrays of horizontally-oriented reservoirs to deliver liquids through microchannels at a constant flow rate over extended periods of time (hours to days). The horizontal orientation maintains a constant hydraulic pressure drop across microfluidic channels even as the volumes of liquids within the reservoirs change over time. For a given channel–reservoir system, the magnitude of the flow velocity depends linearly on the height difference between reservoirs. The simple structure and operation mechanism make this pumping system versatile. A one-inlet–one-outlet system was used to continuously deliver media for perfusion cell culture, and an array of inlet reservoirs coupled to an outlet reservoir via microchannels was used to drive flows of multiple laminar streams. The parallel pumping scheme conveniently generated various smooth and step concentration gradients, and allowed evaluation of the effect of colchicine on myoblasts. Since the reservoir arrays are configured to be compatible with commercialized multichannel pipettors designed for 96 well plate handling, this simple pumping scheme is envisioned to be broadly useful for medium to high throughput microfluidic perfusion cell culture assays, cell migration assays, multiple laminar flow drug tests, and any other applications needing multiple microfluidic streams.