Figure 4.

Schematic of device design and essential parts of OOC. (A) Manufacturing process of the device. A uniform layer of photosensitive material is spin-coated on the silicon wafer and then covered with a photomask with a microscale pattern. The microscale pattern etches into the photoresist after exposure to high-intensity ultraviolet light. PDMS stamps are obtained by casting the PDMS liquid prepolymer onto the etched photoresist pattern (adapted and modified from ref. [4]). (B) Materials of microfluidic chips (adapted and modified from ref. [49]). (C) A sensor system for metabolic monitoring. Nanoparticles embedded in the microtissues measure the Oxygen and pH. Aerometric biosensors downstream connected by a microfluidic switchboard measure the glucose and lactate (adapted and modified from ref. [50]). (D) Adult stem cells (ASCs), primary cells, cell lines, induced pluripotent stem cells (iPSCs), and embryonic stem cells (ESCs) can be differentiated and incorporated into microfluidic chips. (E) Cardiomyocytes are further differentiated and matured under the tension of microcantilevers and electrical stimulation, eventually achieving synchronized beating controlled by electrical stimulation.