Conditioning lab on PCB to control temperature and mix fluids at the microscale for biomedical applications

In this paper, a Lab on PCB (LOP) for conditioning the medium of cell culture is presented. The target is to control its temperature at 37 °C ± 0.1 °C, to assure the appropriate temperature conditions around the cells. The Lab on PCB is also able to mix other fluids into the medium, if it is necessary. The integration of a PDMS microfluidic circuit over a Printed Circuit Board (PCB) results in a smart platform with a low-cost fabrication process. The microfluidic platform of the system includes three inlet ports, microchannels, a micromixer and one outlet port. The correct operation of the LOP assures that the medium is within the adequate conditions in the outlet port. The PCB incorporates a NTC thermistor to measure the temperature, and microheaters that are activated if the medium temperature is under 36.9 °C. The microheater fabrication process consists of patterning the copper layer of the PCB. The NTC thermistor is welded into copper pads and embedded in PDMS to avoid the contact with the fluid. The system is designed to allow the mixing and heating of fluids and it is connected to a cell culture Lab on PCB, and to an electronic control module, which include the electronic adapting circuit of the NTC and the control of the microheaters. The results of this study concerning the heating and mixing of fluids and the monitoring of temperature are successful.