Microfluidics made easy: A robust low-cost constant pressure flow controller for engineers and cell biologists

Abstract

Over the last decade, microfluidics has become increasingly popular in biology and bioengineering. While lab-on-a-chip fabrication costs have continued to decrease, the hardware required for delivering controllable fluid flows to the microfluidic devices themselves remains expensive and often cost prohibitive for researchers interested in starting a microfluidics project. Typically, microfluidic experiments require precise and tunable flow rates from a system that is simple to operate. While many labs use commercial platforms or syringe pumps, these solutions can cost thousands of dollars and can be cost prohibitive. Here, we present an inexpensive and easy-to-use constant pressure system for delivering flows to microfluidic devices. The controller costs less than half the price of a single syringe pump but can independently switch and deliver fluid through up to four separate fluidic inlets at known flow rates with significantly faster fluid response times. It is constructed of readily available pressure regulators, gauges, plastic connectors and adapters, and tubing. Flow rate is easily predicted and calibrated using hydraulic circuit analysis and capillary tubing resistors. Finally, we demonstrate the capabilities of the flow system by performing well-known microfluidic experiments for chemical gradient generation and emulsion droplet production.

Modular 3D Printed Compressed Air Driven Continuous‐Flow Systems for Chemical Synthesis

“…It would also mean that we would need much higher pressures than recommended for the Duran pressure solvent reservoir . Inspired by the use of capillary resistors currently used in the field of microfluidics, we decided to control the hydraulic resistance of our pressure‐driven system and the flow rate by altering the pressure applied according to the Hagen–Poiseuille law [Equation ] which can also be simplified to Equation , where R h is the hydraulic resistance. …”

“…Based on this equation, we would need to know R h of the whole system were we to control the flow rate. However, if the R h of a capillary resistor is greater than that of the whole system, it can readily regulate the flow rate . As the flow system uses 1.0 mm ID tubing and a meso‐scale reactor in the use of the CDRs, we envisaged that addition of easily accessible HPLC PEEK tubing would allow us to develop a suitable set of capillary resistors that would offer sufficient resistance and also be compatible with organic solvents obviating the need for back pressure regulators.…”

Monitoring microfluidic interfacial flows using impedance spectroscopy

“…We used a microfluidic "T-channel" device to create the liquid interface. Two fluid streams were supplied to the microfluidic device using a low-cost constant pressure source flow system [31]. perform an experiment, the fluid interface was subjected to an electric field using the parallel-point electrode array and forced to displace by fDEP at different field frequencies (Fig 1b-d).…”

“…Reynolds number these two fluids formed an interface with a large electrical mismatch between them. Each stream was injected at a constant flow rate (10 μL/min) into the device using a low-cost flow controller equipped with an externally pressurized fluidfilled cryogenic vial [31]. (Invitrogen).…”

A microfluidic gas damper for stabilizing gas pressure in portable microfluidic systems

“…In attempts to control microfluids in a low-cost and portable manner, various techniques for driving liquid flows in microchannels have been proposed, such as compressed gas driven, 6,7 electro-osmotic flow, 8,9 capillary flow, 10,11 hydrostatic force, 12,13 and centrifugal force. 14,15 Although these previously reported techniques show acceptable performances in flow control in microchannels, they are either too complex due to the requirement of external equipments or limited in terms of sample types and volumes.…”