Narrower Nanoribbon Biosensors Fabricated by Chemical Lift-off Lithography Show Higher Sensitivity (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.
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
Biosensors & bioelectronics, 2018
We report on direct label-free protein detection in high ionic strength solution and human plasma by a dual-gate nanoribbon-based ion-sensitive field-effect transistor (NR-ISFET) biosensor system with excellent sensitivity and specificity in both solution-gate (SG) and dual-gate (DG) modes. Compared with previously reported results, the NR-ISFET biosensor enables selective prostate specific antigen (PSA) detection based on antibody-antigen binding in broader detection range with lower LOD. For the first time, real-time specific detection of PSA of 10 pM to 1 μM in 100 mM phosphate buffer (PB) was demonstrated by conductance measurements using the polyethylene glycol (PEG)-modified NR-ISFET biosensors in DG mode with the back-gate bias (V) of 20 V. Due to larger maximum transconductance value resulting from the modulation of NR-ISFET channel by the back gate in DG mode, the detection range can be broadened with larger linear detection region (100 pM to 100 nM) and lower limit of dete...
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.
Nano-FET-enabled biosensors: Materials perspective and recent advances in North America
Biosensors and Bioelectronics, 2020
Field-effect transistor (FET) is a very promising platform for biosensor applications due to its magnificent properties, including label-free detection, high sensitivity, fast response, real-time measurement capability, low running power, and the feasibility to miniaturize to a portable device. 1D (e.g. carbon nanotubes, Si nanowires, conductive polymer nanowires, 1D metal oxides, and others) and 2D (e.g. graphene materials, transition metal dichalcogenides, black phosphorus, and 2D metal oxides) materials, with their unique structural and electronic properties that are unavailable in bulk materials, have helped improve the sensitivity of FET biosensors and enabled detection down to single molecule. In this review, we give insights into the rapidly evolving field of 1D and 2D materials-based FET biosensors, with an emphasis on structure and electronic properties, synthesis, and biofunctionalization approaches of these nanomaterials. In addition, the progress in the 1D/2D-FET biosensors in North America, in the last decade, is summarized in tables. Moreover, challenges and future perspectives of 1D/ 2D-FET biosensors are covered.
Importance of the Debye Screening Length on Nanowire Field Effect Transistor Sensors
Nano Letters, 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. The ability to rapidly sense minute concentrations of specific macromolecules such as DNA sequences is critical for clinical diagnostics, 1,2 genomics, 3,4 and drug discovery 3,4 and useful for applications in defense and homeland security. 5 Most current systems for macromolecular sensing rely on labels, such as radiolabeled tags or fluorophores. 6-8 Techniques that could distinguish these without the need for labels, i.e., label-free sensing, are of great interest because they would not only significantly decrease the cost and time needed for sample preparation but would also eliminate issues related to modification of target molecules. 9,10 One of the most promising platforms for unlabeled sensing is the nanowire field effect transistor (NW-FET). 9-11 These devices operate similarly to conventional chemical FETs, sensing the presence of bound species by their intrinsic charge, with the advantage of enhanced sensitivity due to the nanoscale channel confinement. 11,12 By binding a receptor protein or a singlestranded DNA (ssDNA) oligomer to the NW-FET surface, the binding of the specific ligand or complementary ssDNA modifies the electric field surrounding the device, enabling direct electronic detection. 13-16 The integration issues faced by traditional, as-grown NWs have been overcome with the advent of NW-like devices patterned by "top-down" microlithography. 14-18 Although early devices suffered from low signal-to-noise ratios, a "top-down" method producing high-quality nanosensors capable of detecting specific antibodies at «10 fM concentrations have recently
Programming the detection limits of biosensors through controlled nanostructuring
Nature Nanotechnology, 2009
Advances in materials chemistry offer a range of nanostructured shapes and textures for building new biosensors. Previous reports have implied that controlling the properties of sensor substrates can improve detection sensitivities, but the evidence remains indirect. Here we show that by nanostructuring the sensing electrodes, it is possible to create nucleic acid sensors that have a broad range of sensitivities and that are capable of rapid analysis. Only highly branched electrodes with fine structuring attained attomolar sensitivity. Nucleic acid probes immobilized on finely nanostructured electrodes appear more accessible and therefore complex more rapidly with target molecules in solution. By forming arrays of microelectrodes with different degrees of nanostructuring, we expanded the dynamic range of a sensor system from two to six orders of magnitude. The demonstration of an intimate link between nanoscale sensor structure and biodetection sensitivity will aid the development of high performance diagnostic tools for biology and medicine.
Editorial: Nanotechnological Advances in Biosensors
Sensors, 2009
A biosensor is a physicochemical or hybrid physical-chemical-biological device that detects a biological molecule, organism, or process. Because of the nature of their targets, biosensors need to be faster, smaller, more sensitive, and more specific than nearly all of their physicochemical counterparts or the traditional methods that they are designed to replace. Speed is of the essence in medical diagnosis as it permits for rapid, accurate treatment and does not allow patients to be lost to follow-up. Small size and greater sensitivity mean less-invasive sampling and detection of molecules such as neurotransmitters or hormones at biologically-relevant levels. Greater specificity allows assays to be performed in complex fluids such as blood or urine without false negative or false positive results. Nanotechnology promises to improve biosensing on all of these fronts. Nanofabricated materials can bind directly to biomolecules and/or act as transducers to extremely small and sensitive detectors. Their sensing mechanisms can be sensitive at the single-molecule level, and include standard outputs such as fluorescence and color as well as label-free techniques such as evanescent wave coupling or electrochemistry. This Special Issue reviews and introduces some ways in which nanofabrication and nanomaterials can aid in specific biomolecule detection. Several of the papers present complete lab-on-chip systems for microfluidic sample delivery and analysis. Germano et al. [1] present a biochip that works on the principle of magnetoresistive sensing. Magnetically-tagged targets can be detected down to fM concentrations. A full prototype of the sensor platform is described, including sensing and processing modules (incorporating electric and magnetic drive, signal processing, and digitalization), communication modules, and an analyzer module coupled to a computer. Assadollahi et al. [2] improve the speed and sensitivity of lateral flow devices by creating a microfluidic "dipstick" tester with a readout panel consisting of functionalized Au or Pd nanoparticles. Resonance-enhanced absorption (REA) of these metal particles was used to detect specific binding and could be further amplified with silver stain for increased sensitivity. The device was designed to handle blood or urine. Huang et al. [3] have developed a microfluidic device that amplifies the surface plasmon signal from Au nanoparticles using grooved optical fibers. Binding of an analyte to the functionalized Au particles
Nanotubes/nanowires-based, microfluidic-integrated transistors for detecting biomolecules
Microfluidics and Nanofluidics, 2010
Nanotubes and nanowires have sparked considerable interest in biosensing applications due to their exceptional charge transport properties and size compatibility with biomolecules. Among the various biosensing methodologies incorporating these nanostructured materials in their sensing platforms, liquid-gated field-effect transistors (LGFETs)-based device configurations outperform the conventional electrochemical measurements by their ability in providing label free, direct electronic read-out, and real-time detection. Together with integration of a microfluidic channel into the device architecture, nanotube- or nanowires-based LGFET biosensor have demonstrated promising potential toward the realization of truly field-deployable self-contained lab-on-chip devices, which aim to complement the existing lab-based methodologies. This review addresses the recent advances in microfluidic-integrated carbon nanotubes and inorganic nanowires-based LGFET biosensors inclusive of nanomaterials growth, device fabrication, sensing mechanisms, and interaction of biomolecules with nanotubes and nanowires. Design considerations, factors affecting sensing performance and sensitivity, amplification and multiplexing strategies are also detailed to provide a comprehensive understanding of present biosensors and future sensor systems development.
Dual-gate polysilicon nanoribbon biosensors enable high sensitivity detection of proteins
We demonstrate the advantages of dual-gate polysilicon nanoribbon biosensors with a comprehensive evaluation of different measurement schemes for pH and protein sensing. In particular, we compare the detection of voltage and current changes when top- and bottom-gate bias is applied. Measurements of pH show that a large voltage shift of 491 mV pH −1 is obtained in the subthreshold region when the top-gate is kept at a fixed potential and the bottom-gate is varied (voltage sweep). This is an improvement of 16 times over the 30 mV pH −1 measured using a top-gate sweep with the bottom-gate at a fixed potential. A similar large voltage shift of 175 mV is obtained when the protein avidin is sensed using a bottom-gate sweep. This is an improvement of 20 times compared with the 8.8 mV achieved from a top-gate sweep. Current measurements using bottom-gate sweeps do not deliver the same signal amplification as when using bottom-gate sweeps to measure voltage shifts. Thus, for detecting a small signal change on protein binding, it is advantageous to employ a double-gate transistor and to measure a voltage shift using a bottom-gate sweep. For top-gate sweeps, the use of a dual-gate transistor enables the current sensitivity to be enhanced by applying a negative bias to the bottom-gate to reduce the carrier concentration in the nanoribbon. For pH measurements, the current sensitivity increases from 65% to 149% and for avidin sensing it increases from 1.4% to 2.5%.