Search results

Nanobiosensors based on nanogap capacitor are widely used for measuring dielectric properties of DNA, protein and biomolecule. The purpose of this paper is to report on the fabrication and characterization polysilicon nanogap patterning using novelties technique.

Overall, the polysilicon nanogap pattern was fabricated based on conventional lithographic techniques. For size expansion technique, by employing simple dry thermal oxidation, the couple of nanogap pattern has been expanded to lowest nanogap value. The progress of nanogap pattern expansion was verified by using scanning electron microscopy (SEM). Conductivity, resistivity, and capacitance test were performed to characterize and to measure electrical behavior of full device fabrication.

SEM characterization emphasis on the expansion of polysilicon nanogap pattern increasing with respect to oxidation time. Electrical characterization shows that nanogap enhanced the sensitivity of the device at the value of nano ampere of current.

These simple least‐cost method does not require complicated nanolithography method of fabrication but still possible to serve as biomolecular junction. This approach can be applied extensively to different design of nanogap structure down to several nanometer levels of dimensions. A method of preparing a nanogap electrode according to the present innovation has an advantage of providing active surface that can be easily modified for immobilizations of biomolecules.

Nanogap electrodes have important applications in power saving devices, electrochemical sensors and dielectric detections of biomolecules. The purpose of this paper is to report on the fabrication and characterization of polysilicon nanogap patterning using novelties technique.

Polysilicon material is used to fabricate the nanogap structure and gold is used for the electrode and two chrome masks are used to complete this work; the first mask for the nanogap pattern and a second mask for the electrode. The method is based on the control of the coefficients (temperature and time) with an improved pattern size resolution thermal oxidation.

Physical characterization by scanning electron microscopy (SEM) demonstrates such nanogap electrodes could be produced with high reproducibility and precision. Electrical characterization shows that nanogap enhanced the sensitivity of the device by increase the capacitance and the conductivity as well. They have also good efficiency of power consumption with high insulation properties.

With this technique, there are no principal limitations to fabricating nanostructures with different layouts down to several different nanometer dimensions. The paper documents the fabrication of nanogaps electrodes on a polysilicon, using low‐cost techniques such as vacuum deposition and conventional lithography. Polysilicon is a low‐cost materials and has desirable properties for semiconductor applications. A method of preparing a nanogap electrode according to the present innovation has an advantage of providing active surface that can easily be modified for immobilizations of biomolecules.

The purpose of this paper was to systematically study the electrical properties of 5‐, 42‐ and 75‐nm gap polysilicon structures to evaluate the potentiality of these structures to be used in biomolecular sensing devices.

The authors previously reported the fabrication and morphological characterization of these structures. In this report, they electrically probed the presence of nanogap through current measurement. The effects of electrolytes on the capacitance profiles of these structures were systematically studied with air, water and various dilutions of phosphate buffer saline.

An increment in capacitance was found with the increment in electrolyte concentration. Improvement in current flow, capacitance, permittivity, and conductivity were observed with the smaller size nanogaps, suggesting their applications in low power consuming devices.

Since nanogap‐based dielectric biosensing devices need to be operated with a low level of current to avoid biomolecular damage, these structures should have potential applications in dielectric‐based biomolecular detection using a low cost dielectric analyser.

This paper aims to discuss a nanoscale biosensor and its signal analysis algorithms.

In this work, five nanoscale biosensors are reviewed, namely, silicon nanowire field-effect-transistor biosensors, polysilicon nanogap capacitive biosensors, nanotube amperometric biosensors, gold nanoparticle-based electrochemical biosensors and quantum dot-based electrochemical biosensors.

Each biosensor produces a different output signal depending on its electrical characteristics. Five signal analysers are studied, with most of the existing signal analyser analyses based on the amplitude of the signal. Based on the analysis, auto-threshold peak detection is proposed for further work.

Suitability of the signal processing algorithm to be applied to nano-biosensors was reported.

The purpose of this study is to present reports on fabrication of silicon (Si) nanowires (NWs). The study consists of microwire formation on silicon-on-insulator (SOI) that was fabricated using a top-down approach which involved conventional photolithography coupled with shallow anisotropic etching.

A 5-inch p-type silicon-on-insulator (SOI) coated with 250nm layer and Photoresist (PR) with thickness of 400nm is coated in order to make pattern transfer via binary mask, after the exposure and development, a resist pattern between 3 μm-5 μm were obtained, Oxygen plasma spreen was used to reduce the size of the PR to 800 μm, after this, the wafer with 800 μm was loaded into SAMCO inductively coupled plasma (ICP)-RIE and got silicoon microwire was obtained. Next, the sample was put into an oxidation furnace for 15, 30, 45 and 60 minutes and the sample was removed and dipped into a buffered oxide etch solution for five minutes to remove all the SiO₂ ashes.

The morphological characterization was conducted using scanning electron microscopy and atomic force microscopy. At terminal two, gold electrodes which were designated as source and drain were fabricated on top of individual NWs using conventional lithography electrical and chemical response. Once the trimming process has been completed, the device's current–voltage (I-V) characteristic was measured by using a Keithley 4200 semiconductor parameter analyser. Devices with different width of wires approximately 20, 40, 60 and 80 nm were characterized. The wire current variation as a function of the pH variation in voltage was investigated: pH monitoring for variations of pH values between 5 and 9.

This paper provides useful information on novel and yet simple cost-effective fabrication of SiNW; as such, it should be of interest to a broad readership, especially those interested in micro/nanofabrication.

This paper aims to introduce a series of experimental results which are the extension of our previous novel observations (Xie et al., Soft Matter, 2011), which could be helpful for revealing the lubrication failure mechanism in bearings when they are exposed to an electrical environment.

An experimental apparatus where a ball was in contact with a glass disk coated with a semi-reflective chromium layer. A small volume of oil droplet was put into the microgap of the ball-disk contact. Then, a potential was applied onto the oil micropool formed by the droplet surrounding the contact region.

It has been found that destabilization of the low-conducting oil micropool around the contact region could be induced after applying a potential. Thin oil films could be drained out of the oil pool and spread on the tribopair surfaces, resulting in the depletion of the oil pool. When the applied potential was increased, the occurrence of spreading would be easier and its development would be more obvious. In contrast, the electrospreading behavior would be suppressed when the oil viscosity, contact load and oil pool size were increased. Thermocapillary force due to thermal effect as a result of the current flow near the oil pool border has been proposed as the main driving force for the spreading behavior. The influences of the operating parameters have been ascribed to the change of the electric current near the oil pool border as well as the corresponding variations in the temperature rise and the surface tension of the oil pool.

This is the first study to directly observe that the lubricant oil micropool around the contact region could deplete after applying a potential, potentially resulting in oil starvation in the contact region.

This study aims to investigate the fabrication of hydrogen gas sensor based on metal–oxide–semiconductor (MOS) microstructure. The palladium nanoparticles (PdNPs) as gate metal have been deposited on the oxide film using spin coating.

The PdNPs and the surface of oxide film were analyzed using Transmission electron microscopy. The capacitance-voltage (C-V) curves for the MOS sensor in 1, 2 and 4 per cent hydrogen concentration and in 100 KHz frequency at the room temperature were reported.

The response times for 1, 2 and 4 per cent hydrogen concentration were 2.5 s, 1.5 s and 1 s, respectively. The responses (R per cent) of MOS sensor to 1, 2 and 4 per cent hydrogen concentration were 42.8, 47.3 and 52.6 per cent, respectively.

The experimental results demonstrate that the MOS hydrogen gas sensor based on the PdNPs gate, shows the fast response and recovery compared to other hydrogen gas sensors based on the Pd.

Different types of wood (ash, oak and beech) have been activated by new activation method. The aim of this work is to study the effect of different types of wood on the physical and chemical properties of Ni/Pd coatings.

The wood was activated by ablation of the Pd target using pulsed laser deposition (PLD) technique. Different diagnostic techniques such as X-ray photoelectron spectroscopy (XPS), attenuated total reflection (ATR) spectroscopy and energy dispersed X-ray spectroscopy (EDS), in parallel with scanning electron microscopy (SEM) were used to achieve this goal.

The XPS technique confirmed that the highest concentration of Pd was found in the Pd/beech sample, which is associated to the texture of the beech wood substrate surface. EDS results confirmed the absence of any contamination related to electroless plating method. It is concluded that the wood morphology and its surface roughness play a conclusive role to obtain different quantity of metal by PLD and electroless plating methods.

Although several works have been performed to study the influence of substrates on the coated metals and away of the traditional methods in activating non-catalytic surface, in this paper, PLD method is used to obtain a good quantity of Pd distributed on the entire surface and inside the porous of the wood. This study could be considered as a step investigation for understanding the role of the wood substrate morphology on the physical and chemical properties of films. To our knowledge, there are no works of combining a coated Ni/Pd by electroless plating and PLD methods on wood.

Nanopore-based molecular sensing and measurement, specifically DNA sequencing, is advancing at a fast pace. Some embodiments have matured from coarse particle counters to enabling full human genome assembly. This evolution has been powered not only by improvements in the sensors themselves, but also in the assisting microelectronic CMOS readout circuitry closely interfaced to them. In this light, this paper aims to review established and emerging nanopore-based sensing modalities considered for DNA sequencing and CMOS microelectronic methods currently being used.

Readout and amplifier circuits, which are potentially appropriate for conditioning and conversion of nanopore signals for downstream processing, are studied. Furthermore, arrayed CMOS readout implementations are focused on and the relevant status of the nanopore sensor technology is reviewed as well.

Ion channel nanopore devices have unique properties compared with other electrochemical cells. Currently biological nanopores are the only variants reported which can be used for actual DNA sequencing. The translocation rate of DNA through such pores, the current range at which these cells operate on and the cell capacitance effect, all impose the necessity of using low-noise circuits in the process of signal detection. The requirement of using in-pixel low-noise circuits in turn tends to impose challenges in the implementation of large size arrays.

The study presents an overview on the readout circuits used for signal acquisition in electrochemical cell arrays and investigates the specific requirements necessary for implementation of nanopore-type electrochemical cell amplifiers and their associated readout electronics.