Zika Virus Field Effect Transistor

Abstract

A unique field-effect transistor with an active channel composed of aptamers designed to bind to the Zika virus was fabricated. To immobilize the aptamers in the device channel, we used gold nanoparticles (AuNPs), a 20-40 nm thin film of sputtered gold (Au film), and a molecular sieve material zeolite. The aptamers were functionalized with a thiol end group that enabled them to bind with gold and most other materials. In the case of aptamer/AuNP, when Zika was added to the channel it reduced the channel conductivity from 4.4 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> S/cm to 3.7 S/cm. The gate field effect clearly showed that the aptamer/AuNP channel is p-type with a relatively large transconductance of 300 μS (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS</sub> = 2V) compared to the Zika/aptamer/AuNP channel (also p-type) but with lower transconductance of 2 μ S (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS</sub> = 2V). There was large amount of charge trapping (~10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">15</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) in Zika/aptamer/AuNP channel. In other cases of aptamer/Au film and zeolite channels, there were large changes in the channel conductance when Zika was added. Aptamer/Au and aptamer/zeolite channels were both n-type and their conductivities increased when Zika was added. Combination of AuNP and zeolite biosensing FETs can be used to design complimentary bioFET sensors. We show that the gate voltage in FET biosensors can be used to increase their sensitivity (24 times in Zika/aptamer/AuNP), selectivity and dynamic range (by 10× or more).