A low-cost 3D printed pumping system for generating oscillatory flow in a multicellular lab-on-a-chip device

As microfluidic technology continues to advance, in vitro models have been increasingly utilized to recapitulate complex biological microenvironments. While these systems offer a number of advantages over traditional cell culture methods, they require the ability to precisely manipulate small quantities of fluid. However, commercially produced equipment is often cost-prohibitive for smaller research groups with limited resources. Here, we present the development of an accurate, cost-effective, on-chip pumping system that can generate oscillating fluid flow within a custom-designed microfluidic device. The multilayer chip contains two cell culturing chambers that are separated by a thin permeable membrane. In the upper chamber, an oscillating sinusoidal fluid flow can be induced to mechanically stimulate cells with fluid shear stress. The pump consists of two 3D printed linear actuators that are controlled by an Arduino Mega 2560 microcontroller with custom-written software. To demonstrate the versatility of our system, we verified that a range of physiologically relevant levels of shear stress can be induced at multiple frequencies. Our results show that a maximum shear stress of at least +/- 8 dyn/cm(2) can be induced at frequency of 1 Hz. This corresponds to a maximum volumetric flow rate of approximately 250 mu l/min across an area of 0.33 mm(2). Further, we have demonstrated that while flow is induced in the upper cell culturing chamber, the lower chamber remains in a quasi-static state. This allows for selective mechanical stimulation of cells in the upper chamber, while simultaneously allowing for real-time soluble signaling with unstimulated cells in the lower chamber.