Pressure-Driven Perfusion System to Control, Multiplex and Recirculate Cell Culture Medium for Organs-on-Chips

Abstract

Organ-on-chip (OoC) devices are increasingly used to mimic the tissue microenvironment of cells in intact organs. This includes microchannels to mimic, for example, fluidic flow through blood vessels. Present methods for controlling microfluidic flow in these systems rely on gravity, rocker systems or external pressure pumps. For many purposes, pressure pumps give the most consistent flow profiles, but they are not well-suited for high throughput as might be required for testing drug responses. Here, we describe a method which allows for multiplexing of microfluidic channels in OoC devices plus the accompanying custom software necessary to run the system. Moreover, we show the approach is also suitable for recirculation of culture medium, an essential cost consideration when expensive culture reagents are used and are not “spent” through uptake by the cells during transient unidirectional flow.

Pump-less, recirculating organ-on-a-chip (rOoC) platform

“…This novel way of perfusion may be not only used in the OoC context but might expand to other applications like molecular biology, point-of-care testing or general lab-on-a-chip applications. Compared to pressure-driven systems 10 we don’t need setups with pumps, tubes and controls to generate flow recirculation and compared to systems with integrated pumps 26 we don’t need external driving systems e.g., pneumatic controllers. Internal pumps also require the integration of flexible membranes 14 for fluid manipulation increasing fabrication time and costs and introducing another material into the system potentially influencing the cell behaviour.…”

“…Hence, important features of new generation OoCs include among others the incorporation of blood vessel-like structures, 3D culture models and immune cells. However, existing OoCs that combine these features do it at the cost of low scalability and difficulties in handling [10][11][12][13] .…”

“…Hence, important features of new OoCs generation include among others the incorporation of blood vessel-like structures, 3D culture models and immune cells. Existing OoCs tend to combine these sought-after features at the cost of low scalability and usability [10][11][12][13] . Here we present a novel, scalable, and easy-to-use OoC platform, termed rOoC that not only creates a directed flow without the need for pumps and tubing but also allows the implementation of biological complexity on-chip addressing several of the concerns raised above.…”

Novel Pumping Methods for Microfluidic Devices: A Comprehensive Review

“…de Graaf M. N. S. et al, developed a PID software controller, which integrates constant pressure differences into a fluidic circuit board, for accurate multiplexing of perfusion experiments [ 113 ]. The system is composed of two pneumatic pressure controllers, a flow rate sensor and a microcontroller unit that process and transfer data via serial communication.…”

Multiplexed fluidic circuit board for controlled perfusion of 3D blood vessels-on-a-chip

“…37 We previously described different FCBs to multiplex perfusion in OoCs from highly complex controlled circuits, to simple fluidic "distributing" circuits. [38][39][40] Haemodynamic parameters in 2D-OoCs can be controlled precisely when the dimensions of the culture chambers are known. Therefore, in 2D-OoCs, a single set of perfusion parameters is sufficient for the accurate flow control.…”