# Synthetically Encoded Ultrashort-Channel Nanowire Transistors for Fast, Pointlike Cellular Signal Detection

 Title: Synthetically Encoded Ultrashort-Channel Nanowire Transistors for Fast, Pointlike Cellular Signal Detection Author: Cohen-Karni, Tzahi; Casanova, Didier; Cahoon, James F.; Qing, Quan; Bell, David C.; Lieber, Charles M. Note: Order does not necessarily reflect citation order of authors. Citation: Cohen-Karni, Tzahi, Didier Casanova, James F. Cahoon, Quan Qing, David C. Bell, and Charles M. Lieber. 2012. Synthetically encoded ultrashort-channel nanowire transistors for fast, pointlike cellular signal detection. Nano Letters 12(5): 2639–2644. Full Text & Related Files: synthetically_encoded_ultrashort.pdf (494.6Kb; PDF) Abstract: Nanostructures, which have sizes comparable to biological functional units involved in cellular communication, offer the potential for enhanced sensitivity and spatial resolution compared to planar metal and semiconductor structures. Silicon nanowire (SiNW) field-effect transistors (FETs) have been used as a platform for biomolecular sensors, which maintain excellent signal-to-noise ratios while operating on lengths scales that enable efficient extra- and intracellular integration with living cells. Although the NWs are tens of nanometers in diameter, the active region of the NW FET devices typically spans micrometers, limiting both the length and time scales of detection achievable with these nanodevices. Here, we report a new synthetic method that combines gold-nanocluster-catalyzed vapor–liquid–solid (VLS) and vapor–solid–solid (VSS) NW growth modes to produce synthetically encoded NW devices with ultrasharp (<5 nm) n-type highly doped $$(n^{++})$$ to lightly doped (n) transitions along the NW growth direction, where $$n^{++}$$ regions serve as source/drain (S/D) electrodes and the n-region functions as an active FET channel. Using this method, we synthesized short-channel $$n^{++}/n/n^{++}$$ SiNW FET devices with independently controllable diameters and channel lengths. SiNW devices with channel lengths of 50, 80, and 150 nm interfaced with spontaneously beating cardiomyocytes exhibited well-defined extracellular field potential signals with signal-to-noise values of ca. 4 independent of device size. Significantly, these “pointlike” devices yield peak widths of $$\sim 500 \mu s$$, which is comparable to the reported time constant for individual sodium ion channels. Multiple FET devices with device separations smaller than $$2 \mu m$$ were also encoded on single SiNWs, thus enabling multiplexed recording from single cells and cell networks with device-to-device time resolution on the order of a few microseconds. These short-channel SiNW FET devices provide a new opportunity to create nanoscale biomolecular sensors that operate on the length and time scales previously inaccessible by other techniques but necessary to investigate fundamental, subcellular biological processes. Published Version: doi:10.1021/nl3011337 Other Sources: http://www.ncbi.nlm.nih.gov/pubmed/22468846 Terms of Use: This article is made available under the terms and conditions applicable to Open Access Policy Articles, as set forth at http://nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of-use#OAP Citable link to this page: http://nrs.harvard.edu/urn-3:HUL.InstRepos:10397685 Downloads of this work: