Optimum Cavity Length of a pTFET-Based Biosensor for Successful and Accurate Sensing of a Wide Range of Biomolecules
01 Jan 2021-pp 187-200
TL;DR: A pTFET-based biosensor (pTB-sensor) device is being proposed, and the corresponding detection sensitivity in terms of threshold voltage—sensitivity, threshold voltage (Vth)—shift, subthreshold swing (SS) sensitivity, On current/OFF current (ION/IOFF—shift, leakage power (Pleak)—sensitivity is determined.
Abstract: In this paper, for the first time, a rigorous analysis of determining minimum number of biomolecules and maximum length of the nanogap cavity, used to entrap biomolecules for the detection purpose, has been done. A pTFET-based biosensor (pTB-sensor) device is being proposed, and the corresponding detection sensitivity in terms of threshold voltage (Vth)—sensitivity, threshold voltage (Vth)—shift, subthreshold swing (SS) sensitivity, subthreshold swing (SS) shift, ON current/OFF current (ION/IOFF)—shift, leakage power (Pleak)—sensitivity is determined. It is found that the minimum number of biomolecules or minimum detection limit is 2 for Myoglobin and Apomyoglobin, while the same is 3 for Protein-G, Ferricytochrome-C, and Ferrocytochrome-C, respectively. The maximum biomolecules required for successful detection are found to be 5 for Myoglobin and Apomyoglobin, while the same is 7 for Protein-G, Ferricytochrome-C, and Ferrocytochrome-C, respectively, with 78%, 67%, 41%, 55%, and 50% Vth—sensitivity and 83%, 74%, 53%, 63%, and 58% SS sensitivity for Apomyoglobin, Myoglobin, Protein-G, Ferrocytochrome-C, and Ferricytochrome-C, respectively. This leads to the minimum cavity length of 8 nm and maximum or optimum cavity length to be 20 nm, respectively, for the detection of all the five biomolecules successfully allowing space for scaling down of the channel length to sub-100 nm technology node.
Topics: Threshold voltage (51%)
01 Sep 2008-Biotechnology Advances
TL;DR: The market entry for a new venture is very difficult unless a niche product can be developed with a considerable market volume, and miniaturization must be feasible to allow automation for parallel sensing with ease of operation at a competitive cost.
Abstract: Biosensor technology is based on a specific biological recognition element in combination with a transducer for signal processing. Since its inception, biosensors have been expected to play a significant analytical role in medicine, agriculture, food safety, homeland security, environmental and industrial monitoring. However, the commercialization of biosensor technology has significantly lagged behind the research output as reflected by a plethora of publications and patenting activities. The rationale behind the slow and limited technology transfer could be attributed to cost considerations and some key technical barriers. Analytical chemistry has changed considerably, driven by automation, miniaturization, and system integration with high throughput for multiple tasks. Such requirements pose a great challenge in biosensor technology which is often designed to detect one single or a few target analytes. Successful biosensors must be versatile to support interchangeable biorecognition elements, and in addition miniaturization must be feasible to allow automation for parallel sensing with ease of operation at a competitive cost. A significant upfront investment in research and development is a prerequisite in the commercialization of biosensors. The progress in such endeavors is incremental with limited success, thus, the market entry for a new venture is very difficult unless a niche product can be developed with a considerable market volume.
04 Sep 1996-Journal of the American Chemical Society
TL;DR: The dielectric constants of myoglobin, apomyoglobin, the B fragment of staphylococcal protein A, and the immunoglobulin-binding domain of streptococcalprotein G are calculated from 1−2 ns molecular dynamics simulations in water, using the Frohlich−Kirkwood theory of dielectrics.
Abstract: The dielectric constants of myoglobin, apomyoglobin, the B fragment of staphylococcal protein A, and the immunoglobulin-binding domain of streptococcal protein G are calculated from 1−2 ns molecular dynamics simulations in water, using the Frohlich−Kirkwood theory of dielectrics. This dielectric constant is a direct measure of the polarizability of the protein medium and is the appropriate macroscopic quantity to measure its relaxation properties in response to a charged perturbation, such as electron transfer, photoexcitation, or ion binding. In each case the dielectric constant is low (2−3) in the protein interior, then rises to 11−21 for the whole molecule. The large overall dielectric constant is almost entirely due to the charged protein side chains, located at the protein surface, which have significant flexibility. If these are viewed instead as part of the outer solvent medium, then the remainder of the protein has a low dielectric constant of 3−6 (depending on the protein), comparable to that of ...
22 Feb 2011-IEEE Transactions on Electron Devices
Abstract: A tunnel field-effect transistor (TFET) for which the device operation is based upon a band-to-band tunneling mechanism is very attractive for low-power ultralarge-scale integration circuits. A detailed investigation, with the help of extensive device simulations, of the effects of a spacer dielectric on the device performance of a TFET is reported in this paper. The effects of varying the dielectric constant and width of the spacer are studied. It is observed that the use of a low- dielectric as a spacer causes an improvement in its on-state current. The device performance is degraded with an increase in the spacer width until a certain value (~30 nm); after which, the dependence becomes very weak. The effects of varying the source doping concentration as well as the gate overlap/underlap are also investigated. Higher source doping or a gate-source overlap reduces the spacer dependence of the device characteristics. A gate underlap structure, however, shows an improved performance for a high- spacer. For a given spacer, although a gate overlap or a relatively large gate underlap degrades the device performance, a small gate underlap shows an improvement in it.
15 Jun 2017-Biosensors and Bioelectronics
TL;DR: The packaged OF immunosensor has been validated by a preliminary test on human lung biopsy, which has confirmed the ex-vivo CK17 detection and represents an important milestone towards the detection of biomarkers in tissues, which is still a clinical challenge for minimally-invasive in vivo medical diagnosis.
Abstract: This work presents the development of an innovative plasmonic optical fiber (OF) immunosensor for the detection of cytokeratin 17 (CK17), a biomarker of interest for lung cancer diagnosis. The development of this sensing platform is such that it can be assessed in non-liquid environments, demonstrating that a surface plasmon resonance (SPR) can be excited in this case. For this purpose, detections have been first carried out on CK17 encapsulated in gel matrix in the aim of mimicking tissue samples. Gold-coated OF immunosensors were embedded in a specifically designed packaging providing enough stiffness to penetrate into soft matters. Resulting reflected spectra have revealed, for the first time, the presence of a stable SPR signal recorded in soft matters. Experiments conducted to detect CK17 trapped in a porous polyacrylamide gel matrix have highlighted the specific and selective biosensor response towards the target protein. Finally, the packaged OF immunosensor has been validated by a preliminary test on human lung biopsy, which has confirmed the ex-vivo CK17 detection. Consequently, this work represents an important milestone towards the detection of biomarkers in tissues, which is still a clinical challenge for minimally-invasive in vivo medical diagnosis.
06 May 2016-IEEE Transactions on Electron Devices
Abstract: Dielectrically modulated tunnel FET (DMTFET)-based biosensors show higher sensitivity but lower subthreshold current compared with their dielectrically modulated FET counterpart. In this context, the effect of use of silicon–germanium (SiGe) source and n+-pocket-doped channel is investigated with the help of extensive device-level simulations. This paper explores the underlying physics of germanium composition variation in the source region, and doping concentration variation in n+-pocket region, from the perspective of biomolecule conjugation. The effects of source bandgap and tunneling length over the band-to-band tunneling component have been analyzed, and, subsequently, the sensing performance of DMTFETs has been estimated. The results show that SiGe-source DMTFET has significant superiority over n+-pocket DMTFET for attaining higher subthreshold current level while retaining acceptable sensitivity. Such sensitivity-current optimization has been studied for different gate and drain biases, and the suitable biasing range of operation has been indicated. In addition, the relative efficiency of SiGe source and n+-pocket-doped channel has been studied under different biomolecule sample specifications. Finally, the influence of trap-assisted tunneling on DMTFET sensing performance has been analyzed, and the comparative role of SiGe source and n+ pocket has also been indicated in this context.
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