Field-effect transistor-based biosensors and a portable device for personal healthcare

In this study, miniaturized AlGaN/GaN high electron mobility transistors (HEMTs) were embedded in a plastics substrate and connected with metal electrodes. The plastic substrates were then engraved as the shape of a micro SD card, followed by capping capillary channel for guiding fluids. C-reactive protein (CRP) aptamer were then immobilized on the HEMT for CRP detection. The sensor chip can be inserted into a micro SD card socket, which is connected to a circuit designed for reading out the electrical signals of the sensor. The circuit is controlled by an application software in a laptop. A new methodology was developed to directly detect proteins in high ionic strength solution, such as in 1XPBS or serum, avoiding complicated washing process, leading to less automatics for sample pre-treatment and simpler system and operation. It turns out that the system can be small, cheap, and user-friendly for lay-persons. CRP is demonstrated to be directly detected in human serum with the new methodology. CRP prepared in 1XPBS is successfully detected with this disposable sensor chip and the portable readout device. The result shows that this portable system is promising in personal healthcare in the future.