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Dynamic detection of target-DNA with AlGaN/GaN high electron mobility transistors

: Espinosa, N.; Schwarz, S.U.; Cimalla, V.; Podolska, A.; Ambacher, O.

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Procedia Engineering 120 (2015), pp.908-911
ISSN: 1877-7058
European Conference on Solid-State Transducers (Eurosensors) <29, 2015, Freiburg>
Journal Article, Conference Paper, Electronic Publication
Fraunhofer IAF ()
AlGaN/GaN HEMT; different target-DNA concentration; step input; exponential response; time constant

This work presents a novel, label-free and highly sensitive detection method based on the impedimetric properties of DNA-functionalized AlGaN/GaN HEMTs. Probe-DNA was immobilized on the transistor gate. This layer effectively acts as ion membrane with exponential transient response after a step input. Target-DNA at different concentrations was added (10(-12)- 10(-6) mol/L), and the membrane impedance to diffusion of electrolyte ions was increased after a perfect probe-target matching. The impedance increment was coupled with a slower exponential drain-source current (I(DS)) each step. To quantify this delay, a time constant (T) from the normalized current was calculated. As input, a bipolar square wave voltage was applied to gate with a reference electrode. The time constant for positive or negative input is proportional to the logarithm of target concentration.