The GaAs/AlGaAs-Based Extended Gate HEMT Cardiac Troponin-I Biosensor: Design, Mechanism and Clinical Detection

Herein, we designed several structures of GaAs/AlGaAs extended gate high electron mobility transistors (EG-HEMT) for cTnI detection, in order to explore the mechanism of bio-detection, the limit of detection (LOD) as well as the application in clinical detection. The experiment carried out that 50y structure of EG-HEMT biosensor, whose extended electrode is 50 times as large as the gate, has highest biological regulation ability ( $\delta $ ). Meanwhile, the concentration range of cTnI detection using 50y EG-HEMT biosensor is about 100 fg ml−1 to $10~\mu \text{g}$ ml−1, which is much broader than that of Unicel Dxl800 (usually be used in clinical detection). Furthermore, due to the influence of parasitic resistance and other factors, $\delta $ increases with the increase of y, but the rising rate of $\delta $ decreases at the same time. By comparing the detecting results of clinical samples, 30y EG-HEMT is the best in the detection of cTnI concentration with a relative error of 6%. In a higher concentration range, it is more accurate than that of the Unicel Dxl800, breaking through its limit.