Design Considerations of Silicon Nanowire Biosensors (original) (raw)
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Recent Advances in Silicon Nanowire Biosensors: Synthesis Methods, Properties, and Applications
Nanoscale Research Letters, 2016
The application of silicon nanowire (SiNW) biosensor as a subtle, label-free, and electrical tool has been extensively demonstrated by several researchers over the past few decades. Human ability to delicately fabricate and control its chemical configuration, morphology, and arrangement either separately or in combination with other materials as lead to the development of a nanomaterial with specific and efficient electronic and catalytic properties useful in the fields of biological sciences and renewable energy. This review illuminates on the various synthetic methods of SiNW, with its optical and electrical properties that make them one of the most applicable nanomaterials in the field of biomolecule sensing, photoelectrochemical conversion, and diseases diagnostics.
Top-Down Nanofabrication and Characterization of 20 nm Silicon Nanowires for Biosensing Applications
PloS one, 2016
A top-down nanofabrication approach is used to develop silicon nanowires from silicon-on-insulator (SOI) wafers and involves direct-write electron beam lithography (EBL), inductively coupled plasma-reactive ion etching (ICP-RIE) and a size reduction process. To achieve nanometer scale size, the crucial factors contributing to the EBL and size reduction processes are highlighted. The resulting silicon nanowires, which are 20 nm in width and 30 nm in height (with a triangular shape) and have a straight structure over the length of 400 μm, are fabricated precisely at the designed location on the device. The device is applied in biomolecule detection based on the changes in drain current (Ids), electrical resistance and conductance of the silicon nanowires upon hybridization to complementary target deoxyribonucleic acid (DNA). In this context, the scaled-down device exhibited superior performances in terms of good specificity and high sensitivity, with a limit of detection (LOD) of 10 f...
Lab-on-Chip Silicon nanowire biosensors, for biomedical applications
2012
Low-cost point-of-care medical diagnostic devices are of crucial importance for the future health care system. Lab-on-chip (LOC) systems with silicon nanowires (SiNW) in a Field-effect transistor (FET) setup can be used as biosensors. [1] Due to its high sensitivity and compatibility with a number of LOC technologies SiNWs can be used in a variety of setups, making it an excellent candidate for biosensor devices. In biosensing applications, SiNWs can be functionalized, e.g. with specific antibodies, to ensure selective sensitivity towards a certain target. [2] Detecting small amounts of antigens can for example allow for the diagnosis of diseases in their early stages. Single virus detection using SiNWs has been previously demonstrated [1] , opening the possibility of extremely sensitive diagnostic tools. However, in order to develop a reliable and reproducible diagnostic tool, it is of outmost importance to truly understand the effects that lead to the high sensitivity that can be ...
Investigation of Silicon Nanowire Biosensors Using the 2D Drift-diffusion Model
2007
ABSTRACT Experiments for silicon biosensors with gate lengths in the range of 200nm to 500nm have not been extensively carried out. In this paper, simulations were performed for gate lengths proportionally smaller and greater than regular experimental gate lengths. The sensitivity of the biosensors was simulated using a 2D drift-diffusion model in cylindrical coordinates using the Prophet simulator. In this study simulated conductance results and the respective experimental values [2] are compared.
A Verilog-A model for silicon nanowire biosensors: From theory to verification
Sensors and Actuators B: Chemical, 2013
We present a highly sensitive chemical sensor system including a chip with an array of silicon nanowire ISFETs and a CMOS chip with custom-designed signal-conditioning circuitry. The CMOS circuitry, comprising 8 sigma-delta ( -) modulators and 8 current-to-frequency converters, has been interfaced to each of the nanowires to apply a constant voltage for measuring the respective current through the nanowire. Each nanowire has a dedicated readout channel, so that no multiplexing is required, which helps to avoid leakage current issues. The analog signal has been digitized on chip and transmitted to a host PC via a FPGA. The system has been successfully fabricated and tested and features, depending on the settings, noise values as low as 8.2 pA RMS and a resolution of 13.3 bits while covering an input current range from 200 pA to 3 A. The two readout architectures ( -and current to frequency) have been compared, and measurements showing the advantages of combining a CMOS readout with silicon nanowire sensors are presented: (1) simultaneous readout of different silicon nanowires for high-temporal-resolution experiments and parallel sensor experiments (results from pH and KCl concentration sweeps are presented); (2) high speed measurements showing how the CMOS chip can enhance the performance of the nanowire sensors by compensating its non-idealities as a consequence of hysteresis.
MRS Proceedings, 2012
ABSTRACTHighly sensitive electrolyte-insulator-semiconductor (EIS) sensors were realized by the integration of Si nanowires (NWs), which were fabricated by using a simple and economic electroless wet etching technique. EIS sensors with NWs longer than 1 μm were observed to have considerably increased capacitance and high pH sensitivity. The pH sensitivity of the EIS sensor with 3.8 μm long NWs was 60.2 mV/pH, which is higher than the theoretical Nernstian of 59 mV/pH. The EIS sensors with NWs exhibited slightly worse pH hysteresis and drift properties than that of the conventional planar type EIS sensor. The increases in pH sensitivity, hysteresis and drift are attributable to the extended surface area of the EIS sensors enabled by the NWs.
Towards the silicon nanowire-based sensor for intracellular biochemical detection
Biosensors & Bioelectronics, 2007
A microneedle sensor platform with integrated silicon nanowire tip was developed for intracellular biochemical detection. Because of the virtue of miniaturized size and high sensitivity, this sensor has a great potential for studying individual cell or localized bioenvironment by revealing the pH level and/or enzyme activities. The fabrication of the microneedle sensor was primarily based on conventional silicon processing, where a silicon-on-insulator (SOI) wafer with 50 nm thick (1 0 0) p-type Si device layer was used as the substrate. The silicon nanowires of 50 nm height and 50-100 nm width were created by electron beam (E-beam) lithography on the tip of microneedle with good electrical connection to the contact pads for convenient electrical measurement. A three layer structure with base, support cantilever, and needle tip was designed to ensure convenient handling of sensors and minimize the invasive penetration into biological cells. In this paper, we demonstrate a preliminary assessment of this novel intracellular sensor with electrical conductance measurement under different pH levels. It is expected that this sensor with proper chemical modification will enable localized biochemical sensing within biological cells, such as neurotransmitter activities during the synaptic communication between neuron cells.
Controlled Synthesis of Horizontal Silicon Nanowires for Biosensor Application
Nano, 2015
Top-down silicon nanowire ( SiNW ) fabrication mechanisms for connecting electrodes are widely utilized because they provide good control of the diameter to length ratio. The representative mechanism for the synthesis of SiNWs , a top-down approach, has limitations on the control of their diameter following lithography technologies, requires a long manufacturing process and is not cost-effective. In this study, we have implemented the bottom-up growth of horizontal SiNWs ( H-SiNWs ) on Si / SiO 2 substrates directly by plasma enhanced chemical vapor deposition (PECVD) under about 400°C. The HAuCl4 solution as a catalyst and SiH 4 gas as a precursor are used for the synthesis of H-SiNWs . After optimization of synthesis conditions, we evaluated the photoelectric properties of the H-SiNWs under illumination with different light intensities. Further, we demonstrated the feasibility of H-SiNW devices for the detection of biotinylated DNA nanostructures and streptavidin interaction.
The Development of Silicon Nanowire as Sensing Material
2013
The application of silicon nanowire (SiNW) as a sensing nanomaterial for detection of biological and chemical species has gained attention due to its unique properties. In this review, a short description is also demonstrated on the synthesis techniques of SiNWs and recent progress on sensor development based on electrochemical methods, fluorescence field-effect transistors (FET), and surface-enhanced Raman scattering (SERS) spectroscopy. We also discussed the challenges of SiNW-based sensors in the future.