Effect of nanowire number, diameter, and doping density on nano-FET biosensor sensitivity (original) (raw)
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Investigation of Size Dependence on Sensitivity for Nanowire FET Biosensors
IEEE Transactions on Nanotechnology, 2011
Label-free electrical detection of biomolecules is demonstrated with a double-gate (DG) nanowire (NW) field-effect transistor (FET). Experimental results confirm that detection sensitivity is favorably improved by the increment of NW size in the DG-NWFET, whereas it is enhanced by the decrement of NW size in a conventional single-gate (SG) NWFET. Sensitivity improvement by the augmentation of the NW size in the DG-FET paves the way to overcome technical challenges we face in achieving ultimate miniaturization of the NW size in the SG-FET. This result is comprehensively understood by simple capacitive modeling. The proposed model explains the observed experimental data and provides a design guideline for highly sensitive NW biosensors. Index Terms-Biosensor, capacitive model, double gate (DG), field-effect transistor (FET), nanowire (NW). I. INTRODUCTION B IOSENSORS using a nanowire (NW) field-effect transistor (FET) have great potential in label-free detection of biomolecules at ultralow concentration [1]-[6]. Charged molecules bound to NW surfaces lead to carrier modulation (depletion or accumulation) in the NW, resulting in a current change [7], [8]. A field gating through a solution medium due to charges from the bound molecules can strongly affect the
Applied Physics Letters
The sensing mechanism of nanowire field effect transistor (NWFET) biosensors is investigated by taking into consideration both the charge and dielectric effects of biomolecules. The dielectric effect of the biomolecules is dominantly reflected in the linear regime, whereas the charge property is manifested in the subthreshold regime. The findings are supported by bio-experiments and numerical simulations. This study provides a rudimentary means of understanding interactions between biomolecules and NWFET biosensors. Published by AIP Publishing.
Real-time, label-free detection of biological entities using nanowire-based FETs
Nanotechnology, …, 2008
Nanowire (NW)-based FETs are promising devices with potential applications ranging from health monitoring to drug discovery. In fact, these devices have demonstrated the ability to detect a variety of analytes such as particular DNA sequences, cancer biomarkers, and larger entities such as viruses. These sensor devices have also been used to monitor enzymatic activities and study the behavior of potential drug molecules. The detection of the analytes occurs with high specificity and sensitivity in reasonably short time. Here, we review the recent literature produced in the field of NW FET biosensors. We elaborate on the parameters that ultimately influence device performance such as methods of NW production, device dimensionality, and active measurement conditions. Significant progress has been made in this field of technology; however, it is often difficult to compare literature reports due to differences in both measurement conditions and data analysis. The standardization of certain active measurement conditions, such as the ionic strength of the analyte solutions, and manipulation of data are proposed to facilitate comparison between different NW biosensors.
Addressable Nanowire Field-Effect-Transistor Biosensors With Local Backgates
IEEE Transactions on Electron Devices, 2012
Direct electrical detection of the binding of antibody and antigen of avian influenza virus was demonstrated through a biosensor derived from a double-gate FinFET. A simple detection method was employed in which the charge effect coming from the biomolecules was observed through the threshold voltage V T shift. Due to the presence of a local backgate, the proposed device is individually addressable and the operating voltage is markedly low compared with similar nanowire-type biosensors. Furthermore, its unique structure allows for the channel to be immune to the noise from the biomolecules, which can be problematic for nanogap field-effect-transistor biosensors. The proposed device is complementary metal-oxide-semiconductor compatible and highly reproducible, and monolithic integration with the readout circuits is achievable. Hence, this approach provides a step toward the large-scale development of sensor chips for their potential use in medicine and biotechnology.
Double-Gate Nanowire Field Effect Transistor for a Biosensor
Nano Letters, 2010
A silicon nanowire field effect transistor (FET) straddled by the double-gate was demonstrated for biosensor application. The separated double-gates, G1 (primary) and G2 (secondary), allow independent voltage control to modulate channel potential. Therefore, the detection sensitivity was enhanced by the use of G2. By applying weakly positive bias to G2, the sensing window was significantly broadened compared to the case of employing G1 only, which is nominally used in conventional nanowire FET-based biosensors. The charge effect arising from biomolecules was also analyzed. Double-gate nanowire FET can pave the way for an electrically working biosensor without a labeling process.
Nanowire-Based Electrochemical Biosensors
We review recent advances in biosensors based on one-dimensional (1-D) nanostructure field-effect transistors (FET). Specifically, we address the fabrication, functionalization, assembly/alignment and sensing applications of FET based on carbon nanotubes, silicon nanowires and conducting polymer nanowires. The advantages and disadvantages of various fabrication, functionalization, and assembling procedures of these nanosensors are reviewed and discussed. We evaluate how they have been used for detection of various biological molecules and how such devices have enabled the achievement of high sensitivity and selectivity with low detection limits. Finally, we conclude by highlighting some of the challenges researchers face in the 1-D nanostructures research arena and also predict the direction toward which future research in this area might be directed.
Nanowire Chemical/Biological Sensors: Status and a Roadmap for the Future
Angewandte Chemie International Edition, 2015
Chemiresistive sensors are becoming increasingly important as they offer an inexpensive option to conventional analytical instrumentation, they can be readily integrated into electronic devices, and they have low power requirements. Nanowires (NWs) are a major theme in chemosensor development. High surface area, interwire junctions, and restricted conduction pathways give intrinsically high sensitivity and new mechanisms to transduce the binding or action of analytes. This Review details the status of NW chemosensors with selected examples from the literature. We begin by proposing a principle for understanding electrical transport and transduction mechanisms in NW sensors. Next, we offer the reader a review of device performance parameters. Then, we consider the different NW types followed by a summary of NW assembly and different device platform architectures. Subsequently, we discuss NW functionalization strategies. Finally, we propose future developments in NW sensing to address selectivity, sensor drift, sensitivity, response analysis, and emerging applications. From the Contents 1. Introduction 3 2. Sensory Device Performance Parameters 4 3. Nanowire Types 6 4. NW Assembly and Sensor Fabrication 7 5. Platform Architectures for Sensor Devices 8 6. Functionalization Methods for Applications 9 7. Future Developments 11
2013
We report a specific, label-free and real-time detection of femtomolar protein concentrations with a novel type of nanowirebased biosensor. The biosensor is based on an electrostatically formed nanowire, which is conceptually different from a conventional silicon nanowire in its confinement potential, charge carrier distribution, surface states, dopant distribution, moveable channel and geometrical structure. This new biosensor requires standard integrated-circuit processing with relaxed fabrication requirements. The biosensor is composed of an accumulation-type, planar transistor surrounded by four gates, a backgate, front gate and two lateral gates, and it operates in the all-around-depletion mode. Consequently, adjustment of the four gates defines the dimensions and location of the conducting channel. It is shown that lithographically shaped channels of 400 nm in width are reduced to effective widths of 25 nm upon lateral-gate biasing. Device operation is demonstrated for protein-specific binding, and it is found that sensitive detection signals are recorded once the channel width is comparable with the dimensions of the protein. The device performance is discussed and analyzed with the help of three-dimensional electrostatic simulations.