A Numerical Study of the Heat Distribution Generated by a Microheater in an Organ-on-a-Chip Chamber

In an organ-on-a-chip (OoC), temperature must be kept stable for a well-controlled and human representative microenvironment. This work presents the numerical simulation of a microheater to be integrated in a polydimethylsiloxane chamber that will comprise an OoC. Numerical simulations were performed to evaluate the heat distribution, considering the fluid flow and its direction, the microheater and substrate materials, and the thickness of the oxide layer (electric insulator), on top of the microheater. Silicon (Si) and glass for the substrate, and platinum (Pt) and aluminium (Al) for the microheater materials were evaluated. Results showed that the Si substrate assured better heat uniformity than glass, although reaching lower temperature values, for the same input power. For the microheater, although Al achieved better heat uniformity than Pt, it needed higher current to reach the same temperatures (ranging from 35-45°C). The oxide layer thickness did not affect the achieved temperature. The Si substrate/Pt microheater microsystem was able to heat the fluid chamber up to the 35-45°C range, with current consumption from 0.06 A to 0.1 A, respectively, showing good heat uniformity and low power consumption. Regarding the fluid flow, the domain temperature decreases as the flow rate increases, for the same actuation conditions. It was also analysed the effect of the flux direction and it was observed that, at 120 $\mu\mathrm{L}/\min$, it did not affect the heat distribution in the chamber.