Investigation of Size Dependence on Sensitivity for Nanowire FET Biosensors (original) (raw)
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Effect of nanowire number, diameter, and doping density on nano-FET biosensor sensitivity
ACS nano, 2011
Toronto ON M5S 3G8, Canada^These authors contributed equally to this work. N anowire field-effect transistors (nano-FETs) enable dynamic label-free detection of molecules with higher sensitivity and shorter detection times compared to conventional bioassays. Research efforts over the past decade have produced significant advances in nano-FET biosensor technology and resulted in highly sensitive proofof-concept devices capable of detecting exceedingly low concentrations of proteins, 1À3 nucleic acids, 4,5 and viruses 6 in solution. In order to achieve high performance and consistency across devices, understanding sensing mechanisms and the effect of important parameters is important. A number of experimental studies have been reported, which sought to elucidate the sensing mechanism and the effect of various device parameters on nano-FET sensitivity including electrode material, 7 nanowire composition, 8,9 functionalization method, receptor size, 10,11 gate bias, 12À14 electrolyte ion concentration, 15,16 and analyte delivery methods. 17À19 However, the influence of nanowire number, doping density, and diameter on nano-FET biosensor sensitivity remains to be experimentally quantified.
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.
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.
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.
Importance of the Debye Screening Length on Nanowire Field Effect Transistor Sensors
Nano Lett, 2007
Nanowire field effect transistors (NW-FETs) can serve as ultrasensitive detectors for label-free reagents. The NW-FET sensing mechanism assumes a controlled modification in the local channel electric field created by the binding of charged molecules to the nanowire surface. Careful control of the solution Debye length is critical for unambiguous selective detection of macromolecules. Here we show the appropriate conditions under which the selective binding of macromolecules is accurately sensed with NW-FET sensors.
Modeling and simulation of field-effect biosensors (BioFETs) and their deployment on the nanoHUB
Journal of Physics: …, 2008
Biofets (biologically active field-effect transistors) are biosensors with a semiconductor transducer. Due to recent experiments demonstrating detection by a field effect, they have gained attention as potentially fast, reliable, and low-cost biosensors for a wide range of applications. Their advantages compared to other technologies are direct, label-free, ultrasensitive, and (near) real-time operation. We have developed 2D and 3D multi-scale models for planar sensor structures and for nanowire sensors. The multi-scale models are indispensable due to the large difference in the characteristic length scales of the biosensors: the charge distribution in the biofunctionalized surface layer varies on the Angstrom length scale, the diameters of the nanowires are several nanometers, and the sensor lengths measure several micrometers. The multi-scale models for the electrostatic potential can be coupled to any charge transport model of the transducer. Conductance simulations of nanowire sensors with different diameters provide numerical evidence for the importance of the dipole moment of the biofunctionalized surface layer in addition to its surface charge. We have also developed a web interface to our simulators, so that other researchers can access them at the nanohub and perform their own investigations.
Detection Limit of ultra-scaled Nanowire Biosensors
Abstract—The fundamental detection limit of ultra-scaled Si nanowire FET (NWT) biosensors is studied with a NEGF quantum microscopic approach. For negatively charged analytes, a N-doped NWT is found to be more sensitive and to get less sensitivity degradation when increasing channel length. Our results predict threshold voltage shifts due to a single charge analyte on the order of tens to hundreds of mV in dry (air) or low ionic solution environments, which hint at single charge/analyte detection.
A comprehensive Analysis of Nanoscale Transistor Based Biosensor: A Review
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Imperative introduction of biosensor in the field of medicine, defence, food safety, security and environmental contamination detection acquired paramount attraction. Thus the foundation of the fame of biosensors in detecting wide scope of biomolecules in innumerable fields has driven researchers in advancement of biosensor and enhancing more updates in devices. Among all semiconductor-FET based biosensors grab attraction due to their miniaturization, mass production, ultra-sensitive in nature, improved lifetime, rapid response and reduce thermal budgets. In this review, field effect based biosensors sensitive to ions their principle model along with pros and cons of different structures. Various performance characteristics for semiconductor based biosensor are explored along with detection of label free analytes such as tuberculosis, glucose, antigen 85-B with ISFET. Following with comprehensive detail on MOSFET junction less Silicon based Dual Gate Biosensor with their design para...
Sensors and Actuators B: Chemical, 2013
Silicon nanowire (SiNW) field effect transistors (FETs) have been widely investigated as biological sensors for their remarkable sensitivity due to their large surface to volume ratio (S/V) and high selectivity towards a myriad of analytes through functionalization. In this work, we propose a long channel (L > 500 nm) junctionless nanowire transistor (JNT) SiNW sensor based on a highly doped, ultrathin body field-effect transistor with an organic gate dielectric ε r = 1.7. The operation regime (threshold voltage V th ) and electrical characteristics of JNTs can be directly tuned by the careful design of the NW/Fin FET. JNTs are investigated through 3D Technology Computer Aided Design (TCAD) simulations performed as a function of geometrical dimensions and channel doping concentration N d for a p-type tri-gated structure. Two different materials, namely, an oxide and an organic monolayer, with varying dielectric constants ε r provide surface passivation. Mildly doped N d = 1 × 10 19 cm −3 , thin bodied structures (fin width F w < 20 nm) with an organic dielectric (ε r = 1.7) were found to have promising electrical characteristics for FET sensor structures such as V th ∼ 0 V, high relative sensitivities in the subthreshold regime S > 95%, high transconductance values at threshold g m,Vfg=0 V > 10 nS, low subthreshold slopes SS ∼ 60 mV/dec, high saturation currents I d,max ∼ 1-10 A and high I on /I off > 10 4 -10 10 ratios. Our results provide useful guidelines for the design of junctionless FET nanowire sensors that can be integrated into miniaturized, low power biosensing systems. ), yordan.georgiev@tyndall.ie (Y.M. Georgiev), matthieu.berthome@epfl.ch (M. Berthomé), adrian.ionescu@epfl.ch (A.M. Ionescu). 0925-4005/$ -see front matter