Back-gated spray-deposited carbon nanotube thin film transistors operated in electrolytic solutions: an assessment towards future biosensing applications

• Published in: Journal of materials chemistry. B, Materials for biology and medicine Vol. 1; no. 31; pp. 3797 - 3802
• Main Authors: Münzer, A M, Heimgreiter, M, Melzer, K, Weise, A, Fabel, B, Abdellah, A, Lugli, P, Scarpa, G
• Format: Journal Article
• Language: English
• Published: England 21.08.2013
• Subjects: Buffers; Carbon nanotubes; Concentration (composition); Electrolytes; Semiconductor devices; Thin films; Threshold voltage; Transistors
• ISSN: 2050-750X; 2050-7518
• DOI: 10.1039/c3tb20170h

We report on back-gated carbon nanotube (CNT) thin-film transistors (CNTFETs) and their performance in electrolytic solutions to assess their suitability for future application as biosensors. Spray-deposited CNT networks were used as the sensitive active layer which offers the opportunity for integration on flexible sensing platforms at low-cost. We characterized the transistors' behavior in electrolytes by analyzing the response to different KCl solutions and buffers over a wide pH range. We observed a linear response of the drain current upon changing the pH in low molarity buffers and obtained an exponential dependence on the salt concentration of the electrolyte. These responses can be attributed to electrostatic gating effects that go along with shifts in the threshold voltage. Even though a lot of effort has been put into understanding the biosensing mechanism a detailed theory is still missing. Back-gated CNTFETs operated in electrolytic solutions can be a further tool to investigate and clarify the existing unsolved phenomena.