A Salivary Urea Sensor Based on Microsieve Disposable Gate AlGaN/GaN High Electron Mobility Transistor
The abundant bio-markers in saliva provide a new option for non-invasive testing. However, due to the presence of impurities in the saliva backgroud, most of the existing saliva testing methods rely on pre-processing, which limits the application of saliva testing as a convenient means of testing in daily life. Herein, a disposible-gate AlGaN/GaN high electron mobility transistor (HEMT) biosensor integrated with micro-sieve was intoduced to solve the problem that signal interference caused by charged impurities in saliva for HEMT based biosensors, where the micro-sieve was ultilized as a pre-treatment unit to remove large particles of impurities from saliva through size effect and thus greatly inproving the accuracy of detection. The experimental results showed that the HEMT based biosensor has has excellent linearity (R2 = 0.9977) and a high sensitivity of 6.552 µA·dec−1 for urea sensing from 1 fM to 100 mM in 0.1×PBS solution. When it comes to artificial saliva detection, compare to the HEMT sensor without micro-sieve (sensitivity = 3.07432μA·dec−1), the sensitivity of HEMT sensor integrated with micro-sieve had almost no change. Moreover, to verify that urea can be detected in actual saliva, urea is sensed directly in human saliva. The addition of the microsieve module provides a new way for biosensors to detect specific markers in saliva in real time, and the designed HEMT biosensor with microsieve function has a wide range of application potential in rapid saliva detection.
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