| 1. |
- Chung, Nguyen Xuan, et al.
(författare)
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Optimized electrochemical breakdown etching using temporal voltage variation for formation of nanopores in a silicon membrane
- 2021
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 331
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Tidskriftsartikel (refereegranskat)abstract
- Dielectric breakdown etching is a well-known method of making nanopores on thin (similar to 50 nm) dielectric membranes. However, voltage driven translocation of biomolecules through such nanopores becomes extremely fast. For improved detection, for instance by the current blockage, a high-aspect-ratio nanopore could be beneficial for slowing down the translocation. High-aspect-ratio nanopore on silicon fabrication requires a well-controlled process and is dependent on specific crystal orientation, dopant type and resistivity of substrate. Therefore, an optimized method of processing high-aspect-ratio nanopores is necessary considering the advantage of a silicon membrane being able to be integrated with standard CMOS processing. Here, we present an optimized fabrication method for mass-producing a single and an array of nanopores on a thick (2 mu m) silicon device layer based on a silicon-on-insulator (SOI) wafer. A method of temporal voltage variation is exploited to optimize the etching parameters for the nanopore formation during electrochemical breakdown etching, diameters of nanopores around 12 nm have been achieved. Besides, the correlation between the parameters of etching and nanopore diameter is deduced. The processed high-aspect-ratio nanopore enables applications in single-molecule sensing such as DNA, exosomes, viruses, and protein markers. The developed process is inexpensive, fast and can be batch fabricated.
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| 2. |
- Gatty, Hithesh Kumar, 1980-, et al.
(författare)
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A ppb level, miniaturized fast response amperometric nitric oxide sensor for asthma diagnostics
- 2013
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Ingår i: Micro Electro Mechanical Systems (MEMS), 2013 IEEE 26th International Conference on. - New York : IEEE. - 9781467356541 ; , s. 1001-1004
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Konferensbidrag (refereegranskat)abstract
- This paper reports on a novel miniaturized MEMS-based amperometric nitric oxide sensor that is suitable for a point of care testing device for asthma. The novelty lies in the combination of a high surface area microporous structured electrode, nano-structured Nafion that is coated on the side walls of the micropores, and liquid electrolyte. This combination allows detection of very low concentration (parts-per-billion) gas, has a high sensitivity of 4 mu A/ppm/cm(2) and has both a response and a recovery time of 6 s. The sensor is integrated with a PCB potentiostat to form a complete measuring module. The limit of detection of this sensor was estimated to be 0.3 ppb.
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| 3. |
- Gatty, Hithesh Kumar, et al.
(författare)
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A wafer-level liquid cavity integrated amperometric gas sensor with ppb-level nitric oxide gas sensitivity
- 2015
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Ingår i: Journal of Micromechanics and Microengineering. - : Institute of Physics Publishing (IOPP). - 0960-1317 .- 1361-6439. ; 25:10
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Tidskriftsartikel (refereegranskat)abstract
- A miniaturized amperometric nitric oxide (NO) gas sensor based on wafer-level fabrication of electrodes and a liquid electrolyte chamber is reported in this paper. The sensor is able to detect NO gas concentrations of the order of parts per billion (ppb) levels and has a measured sensitivity of 0.04 nA ppb(-1) with a response time of approximately 12 s. A sufficiently high selectivity of the sensor to interfering gases such as carbon monoxide (CO) and to ammonia (NH3) makes it potentially relevant for monitoring of asthma. In addition, the sensor was characterized for electrolyte evaporation which indicated a sensor operation lifetime allowing approximately 200 measurements.
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| 4. |
- Schröder, Stephan, 1979-, et al.
(författare)
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A low-cost nitric oxide gas sensor based on bonded gold wires
- 2017
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Ingår i: TRANSDUCERS 2017 - 19th International Conference on Solid-State Sensors, Actuators and Microsystems. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538627310 ; , s. 1457-1460
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Konferensbidrag (refereegranskat)abstract
- In this paper we report of a novel and very simple fabrication method for realizing amperometric gas sensors using conventional wire bonding technology. Working and counter electrodes are made of 360 vertically standing bond wires, entirely manufactured by a fully automated, standard wire bonding tool. Our process enables standing bond wires with a length of 1.24 mm, resulting in an extremely high aspect-ratio of 50, thus effectively increasing the surface area of the working electrode. All gas sensor electrodes are embedded in a polymer-based, solid electrolyte. Therefore, laborious handling of liquid electrolytes can be avoided. Here, we report of a nitric oxide (NO) gas sensor that is capable of detecting NO gas concentrations down to the single-digit ppm range. The proposed approach demonstrates the feasibility towards a scalable and entire back-end fabrication concept for low-cost NO gas sensors.
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| 5. |
- Zhou, Jingjian, et al.
(författare)
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Photoluminescence Intensity Enhancement of Single Silicon Quantum Dots on a Metal Membrane with a Spacer
- 2020
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Ingår i: Physica Status Solidi (a) applications and materials science. - : WILEY-V C H VERLAG GMBH. - 1862-6300 .- 1862-6319. ; 217:4
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Tidskriftsartikel (refereegranskat)abstract
- Silicon quantum dots (Si QDs) featuring high photoluminescence (PL) intensity are necessary for the realization of different photonic and photovoltaic devices, such as light-emitting diodes (LEDs) and luminescent solar concentrators (LSCs). Herein, Si QDs on a approximate to 100-200 nm thin silicon dioxide membrane with a metal back-coating are prepared. The dots are formed from the device layer of a silicon-on-insulator (SOI) wafer by etching and thermal oxidation. Aluminum is sputtered on the backside of the membrane, acting as a back-surface mirror, changing the local density of optical modes, as well as the local excitation field. The PL properties of such Si QDs are then characterized at the single-particle level. It is found that the PL yield of single Si QDs on the membrane is enhanced by approximately one order of magnitude, compared with that of Si QDs outside the membrane under the same excitation power. These results indicate that advances in nanofabrication can substantially improve the optical properties of Si QDs, thus paving the way for their application.
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