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Unformatted text preview: Silicon-based nanochannel glucose sensor Xihua Wang, Yu Chen, Katherine A. Gibney, a ! Shyamsunder Erramilli, and Pritiraj Mohanty b ! Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA s Received 15 November 2007; accepted 17 December 2007; published online 8 January 2008 d Silicon nanochannel biological field effect transistors have been developed for glucose detection. The device is nanofabricated from a silicon-on-insulator wafer with a top-down approach and surface functionalized with glucose oxidase. The differential conductance of silicon nanowires, tuned with source-drain bias voltage, is demonstrated to be sensitive to the biocatalyzed oxidation of glucose. The glucose biosensor response is linear in the 0.58 m M concentration range with 35 min response time. This silicon nanochannel-based glucose biosensor technology offers the possibility of high density, high quality glucose biosensor integration with silicon-based circuitry. 2008 American Institute of Physics . f DOI: 10.1063/1.2832648 g Field effect devices, such as capacitive electrolyte- insulator-semiconductor sensor, light-addressable potentio- metric sensor, and ion-sensitive field effect transistor s ISFET d for glucose detection, 1 3 have been extensively stud- ied in recent years. Although these devices are limited by the dependence of the sensor response on buffer capacity, ionic strength, and p H of the test sample, their compatibility with advanced microfabrication technology may enable their po- tential commercialization. Glucose biosensor is a particularly attractive enzyme biosensor due to its potential widespread use in clinical applications. Currently, glucose detection is mostly limited to in vitro test of blood samples, although it is more meaningful to per- form in vivo test by implantable sensing devices for contin- ued monitoring of blood glucose level. To this end, nanoscale sensors may be fundamentally valuable. Semiconductor nanowires, grown from bottom-up approach, have been dem- onstrated as good candidates for ultrasensitive biosensors in many applications. 4 6 However, most of the existing studies based on bottom-up approaches face the limitation of com- plex integration and scalable large-scale manufacturing. Fabrication of silicon nanoscale devices with top-down approaches 7 , 8 using lithography has the inherent benefit of standard semiconductor processes and, hence, better control of device properties. Therefore, field effect devices, using nanoscale technology, offer the possibility of high- performance, low-cost implantable glucose biosensors. Here, we demonstrate silicon nanochannels, surface functionalized with glucose oxidase, as a field effect glucose biosensor. The glucose biosensor with a set of silicon nano- wires as nanochannels, 50100 nm wide, 100 nm high, and 6 m m long, is fabricated from a silicon-on-insulator s SOI d wafer. Figure 1 shows a typical scanning electron micro-...
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