M*: On-Chip Microfluidic Operations With A-Star for Portable Diagnostics

Precise microfluidic control is essential for biomedical diagnostics. Compared to traditional PCB-based DMFB, standard CMOS-based digital microfluidic biochips (DMFB) can integrate sensing, heating, and actuation on a single chip, eliminating the need for external equipment [1]. However, CMOS-DMFB are limited by their lower actuation voltage (usually around 90 V [2]), and their actuation stability is often not as good as that of PCB-DMFB, which can be operated at voltages as high as 300 V [3]. This is due to the fact that, according to research, the EWOD force is proportional to the square of the actuation voltage [4]. In other words, a CMOS-DMFB will only generate approximately 4% of the actuation force of a PCB-DMFB, making actuation not as easy as expected [5]. To alleviate this limitation, we would like to utilize the real-time sensing function on the chip as an actuation feedback. After each actuation, the sensing results can be used to re-adjust the path and determine whether the destination has been reached. Therefore, we designed M* algorithms for on-chip microfluidic operation using A* algorithms to improve the actuation efficiency and accuracy, which is important for high-precision biomedical applications.