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Raman S, K V M, S V, Sankar A R. Silicon nanowire piezoresistor and its applications: a review. NANOTECHNOLOGY 2024; 35:362003. [PMID: 38848697 DOI: 10.1088/1361-6528/ad555e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 06/07/2024] [Indexed: 06/09/2024]
Abstract
Monocrystalline bulk silicon with doped impurities has been the widely preferred piezoresistive material for the last few decades to realize micro-electromechanical system (MEMS) sensors. However, there has been a growing interest among researchers in the recent past to explore other piezoresistive materials with varied advantages in order to realize ultra-miniature high-sensitivity sensors for area-constrained applications. Of the various alternative piezoresistive materials, silicon nanowires (SiNWs) are an attractive choice due to their benefits of nanometre range dimensions, giant piezoresistive coefficients, and compatibility with the integrated circuit fabrication processes. This review article elucidates the fundamentals of piezoresistance and its existence in various materials, including silicon. It comprehends the piezoresistance effect in SiNWs based on two different biasing techniques, viz., (i) ungated and (ii) gated SiNWs. In addition, it presents the application of piezoresistive SiNWs in MEMS-based pressure sensors, acceleration sensors, flow sensors, resonators, and strain gauges.
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Affiliation(s)
- Srinivasan Raman
- Centre for Innovation and Product Development (CIPD), Vellore Institute of Technology (VIT), Chennai campus, Chennai 600 127, Tamil Nadu, India
- School of Electronics Engineering (SENSE), Vellore Institute of Technology (VIT), Chennai campus, Chennai 600 127, Tamil Nadu, India
| | - Meena K V
- Mirrorcle Technologies Inc, Richmond, CA 94804, United States of America
| | - Vetrivel S
- Saint-Gobain Research India, IIT Madras Research Park, Taramani, Chennai 600 113, Tamil Nadu, India
| | - Ravi Sankar A
- Centre for Innovation and Product Development (CIPD), Vellore Institute of Technology (VIT), Chennai campus, Chennai 600 127, Tamil Nadu, India
- School of Electronics Engineering (SENSE), Vellore Institute of Technology (VIT), Chennai campus, Chennai 600 127, Tamil Nadu, India
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Syms R, Bouchaala A. MEMS Electrostatically Driven Coupled Beam Filter Banks. MICROMACHINES 2023; 14:2214. [PMID: 38138383 PMCID: PMC10745592 DOI: 10.3390/mi14122214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 12/01/2023] [Accepted: 12/04/2023] [Indexed: 12/24/2023]
Abstract
MEMS bandpass filters based on electrostatically driven, mechanically coupled beams with in-plane motion have been demonstrated up to the VHF band. Filters higher than second order with parallel plate drives have inherent tuning difficulties, which may be resolved by adding mass-loaded beams to the ends of the array. These beams deflect for DC voltages, and thus allow synchronized electrostatic tuning, but do not respond to in-band AC voltages and hence do not interfere with dynamic synchronization. Additional out-of-band responses may be damped, leaving the desired response. The principle is extended here to close-packed banks of filters, with adjacent arrays sharing mass-loaded beams that localize modes to sub-arrays. The operating principles are explained using a lumped element model (LEM) of the equations of motion in terms of resonant modes and the reflection of acoustic waves at discontinuities. Performance is simulated using the LEM and verified using the more realistic stiffness matrix method (SMM) for banks of up to eight filters. Similar or dissimilar filters may be combined in a compact arrangement, and the method may be extended to higher order resonances and alternative coupled resonator systems.
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Affiliation(s)
- Richard Syms
- Department of Electrical and Electronic Engineering, Imperial College London, Exhibition Road, London SW7 2AZ, UK;
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Syms R, Bouchaala A. Mechanical Synchronization of MEMS Electrostatically Driven Coupled Beam Filters. MICROMACHINES 2021; 12:mi12101191. [PMID: 34683242 PMCID: PMC8539592 DOI: 10.3390/mi12101191] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 09/21/2021] [Accepted: 09/25/2021] [Indexed: 11/24/2022]
Abstract
Micro-electromechanical systems (MEMS) bandpass filters based on arrays of electrostatically driven coupled beams have been demonstrated at MHz frequencies. High performance follows from the high Q-factor of mechanical resonators, and electrostatic transduction allows tuning, matching and actuation. For high-order filters, there is a conflict between the transduction mechanism and the coupling arrangement needed for dynamic synchronization: it is not possible to achieve synchronization and tuning simultaneously using a single voltage. Here we propose a general solution, based on the addition of mass-loaded beams at the ends of the array. These beams deflect for direct current (DC) voltages, and therefore allow electrostatic tuning, but do not respond to in-band alternating current (AC) voltages and hence do not interfere with synchronization. Spurious modes generated by these beams may be damped, leaving a good approximation to the desired response. The approach is introduced using a lumped element model and verified using stiffness matrix and finite element models for in-plane arrays with parallel plate drives and shown to be tolerant of the exact mass value. The principle may allow compensation of fabrication-induced variations in complex filters.
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Kilinc Y, Karakan MÇ, Leblebici Y, Hanay MS, Alaca BE. Observation of coupled mechanical resonance modes within suspended 3D nanowire arrays. NANOSCALE 2020; 12:22042-22048. [PMID: 33146204 DOI: 10.1039/d0nr06659a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Complex yet compact nanoscale mechanisms have largely been absent due to the rather limited availability of components and integration techniques. Especially missing have been efficient interconnects with adjustable characteristics. To address this issue, we report here, for the first time, the transduction of collective modes in vertically stacked arrays of silicon nanowires suspended between couplers. In addition to the ambitious miniaturization, this composite resonator enables the control of coupling strength through the lithographic definition of coupler stiffness. A direct link is thus established between coupling strength and spectral response for two array architectures with nominally identical resonators but different couplers. A series of unique observations emerged in this platform, such as the splitting of a single mode into two closely spaced modes which raises the possibility of tunable bandpass filters with enhanced spectrum characteristics. Finally, intermodal coupling strengths were measured providing strong evidence about the collective nature of these modes.
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Affiliation(s)
- Yasin Kilinc
- Dept. Mechanical Engineering, Koç University, Rumelifeneri Yolu, 34450 Sariyer, Istanbul, Turkey.
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Dolabella S, Frison R, Chahine GA, Richter C, Schulli TU, Tasdemir Z, Alaca BE, Leblebici Y, Dommann A, Neels A. Real- and Q-space travelling: multi-dimensional distribution maps of crystal-lattice strain (∊ 044) and tilt of suspended monolithic silicon nanowire structures. J Appl Crystallogr 2020; 53:58-68. [PMID: 32047404 PMCID: PMC6998783 DOI: 10.1107/s1600576719015504] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 11/15/2019] [Indexed: 11/10/2022] Open
Abstract
Silicon nanowire-based sensors find many applications in micro- and nano-electromechanical systems, thanks to their unique characteristics of flexibility and strength that emerge at the nanoscale. This work is the first study of this class of micro- and nano-fabricated silicon-based structures adopting the scanning X-ray diffraction microscopy technique for mapping the in-plane crystalline strain (∊044) and tilt of a device which includes pillars with suspended nanowires on a substrate. It is shown how the micro- and nanostructures of this new type of nanowire system are influenced by critical steps of the fabrication process, such as electron-beam lithography and deep reactive ion etching. X-ray analysis performed on the 044 reflection shows a very low level of lattice strain (<0.00025 Δd/d) but a significant degree of lattice tilt (up to 0.214°). This work imparts new insights into the crystal structure of micro- and nanomaterial-based sensors, and their relationship with critical steps of the fabrication process.
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Affiliation(s)
- Simone Dolabella
- EMPA, Swiss Federal Laboratories for Materials Science and Technology, Center for X-ray Analytics, Dübendorf, Switzerland
- Department of Chemistry, University of Fribourg, Fribourg, Switzerland
| | - Ruggero Frison
- EMPA, Swiss Federal Laboratories for Materials Science and Technology, Center for X-ray Analytics, Dübendorf, Switzerland
| | - Gilbert A. Chahine
- ID01, European Synchrotron Radiation Facility (ESRF), 38043 Grenoble, France
- Universitè Grenoble Alpes, CNRS, Grenoble INP, SIMAP 38000, France
| | - Carsten Richter
- ID01, European Synchrotron Radiation Facility (ESRF), 38043 Grenoble, France
| | - Tobias U. Schulli
- ID01, European Synchrotron Radiation Facility (ESRF), 38043 Grenoble, France
| | - Zuhal Tasdemir
- Department of Mechanical Engineering, Koc University, Sariyer, Istanbul 34450, Turkey
| | - B. Erdem Alaca
- Department of Mechanical Engineering, Koc University, Sariyer, Istanbul 34450, Turkey
- Surface Science and Technology Center (KUYTAM), Koc University, Sariyer, Istanbul Turkey
| | - Yusuf Leblebici
- École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
- Sabanci University, Istanbul, Turkey
| | - Alex Dommann
- EMPA, Swiss Federal Laboratories for Materials Science and Technology, Center for X-ray Analytics, Dübendorf, Switzerland
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Antonia Neels
- EMPA, Swiss Federal Laboratories for Materials Science and Technology, Center for X-ray Analytics, Dübendorf, Switzerland
- Department of Chemistry, University of Fribourg, Fribourg, Switzerland
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