Design Aspects, Development, and Sensitivity Analysis of GaN HEMT-Based Biosensing Platform for Label-Free Detection of Interleukin-6

Severe TBI survivors face long-term brain damage requiring accurate diagnosis and early treatment as the therapeutic time window typically ranges from minutes to hours before the secondary injury. In this work, we report design aspects and development of an ultrasensitive GaN HEMT-based biosensing platform for IL-6 detection along with novel design correlation equations for sensitivity analysis. Design analysis reveals that the lower value of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="italic">sd</mml:mi> </mml:mrow> </mml:msub> </mml:math> is desirable for enhanced sensitivity as the biosensor with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="italic">sd</mml:mi> </mml:mrow> </mml:msub> </mml:math> of 10 μm offers a peak sensitivity of 129.20 μA pg −1 ml −1 as compared to 25 and 50 μm with a sensitivity of 70.76 and 35.60 μA pg −1 ml −1 respectively. Furthermore, the peak sensitivity reaches as high as 158.01 μA pg −1 ml −1 when the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>W</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>g</mml:mi> </mml:mrow> </mml:msub> </mml:math> was increased from 100 to 250 μm for biosensors with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="italic">sd</mml:mi> </mml:mrow> </mml:msub> </mml:math> of 10 μm using conventional gate design. An increase in sensitivity from 70.76 to 88.40 μA pg −1 ml −1 was observed when a meander gate biosensor was used. An analysis of the EDC-NHS coupling process reveals an enhancement in sensitivity from 78.60 to 129.20 μA pg −1 ml −1 for the EDC-NHS coupled biosensor. The peak response of the biosensor for IL-6 detection was observed at 5 min after the drop cast of antigens over the sensing areas.