Advances in Ultrasensitive Piezoresistive Sensors: from Conventional to Flexible and Stretchable Applications

ABSTRACTThis paper presents a novel approach to create silicon nanostructures with controlled sidewall profiles. The nanostructures are fabricated by alternating the reactive ion etching process and the exposure process to the atmosphere with moisture. The air exposure is believed attributed to the sidewall passivation by facilitating the fast formation of a thin SiO2/SiOxFy layer. Using this approach, three types of representative nanostructures are demonstrated, namely: nanopillars with vertical sidewall, nanopillars with narrowed necks, and suspending nanocantilevers. Without requiring expensive facilities and extensive expertise, this work is expected to provide an alternative for developing nanostructures with a variety of geometric profiles for mechanical sensing applications.

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On the Use of Carbon Nanotubes to Develop Durable Structural Electrodes for Self-Sensing Applications

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.827.458 ◽

2019 ◽

Vol 827 ◽

pp. 458-463

Author(s):

Sotirios A. Grammatikos ◽

Morten Melby Dahl ◽

Vegar Salin Brøndbo ◽

Angela Daniela La Rosa

Keyword(s):

Carbon Nanotubes ◽

Piezoresistive Sensors ◽

Optimum Synthesis ◽

Sensing Applications ◽

Reinforced Polymer ◽

Carbon Fibre Reinforced Polymer ◽

Cfrp Composite ◽

Multi Walled Carbon Nanotubes ◽

Fibre Reinforced Polymer ◽

Walled Carbon Nanotubes

This paper reports an experimental investigation on embedded polyurethane (PUR) electrodes into a carbon fibre reinforced polymer (CFRP) composite to enable the dependable use of composites as a piezoresistive sensors, among other uses, and pave the way towards advanced structural health monitoring (SHM). To be able to use polyurethane as electrodes, multi-walled carbon nanotubes (MWCNTs) were used as fillers in PUR to increase its electrical conductivity. Various concentrations of MWCNTs in PUR were tested to reveal the optimum synthesis. This was conducted by performing mechanical and electrical property tests of the electrodes, studying the adhesion capabilities between composite matrix and polyurethane electrode and carrying out load-unload testing where the composite acts as a strain sensor.

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Fabrication, modelling and assessment of hybrid 1-D elastic Fabry Perot microcavity for mechanical sensing applications

Ceramics International ◽

10.1016/j.ceramint.2019.01.083 ◽

2019 ◽

Vol 45 (6) ◽

pp. 7785-7788 ◽

Cited By ~ 4

Author(s):

Osman Sayginer ◽

Alessandro Chiasera ◽

Lidia Zur ◽

Stefano Varas ◽

Lam Thi Ngoc Tran ◽

...

Keyword(s):

Sensing Applications ◽

Fabry Perot ◽

Mechanical Sensing

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Mechanical Properties Evolution of Polydimethylsiloxane During Crosslinking Process

MRS Proceedings ◽

10.1557/proc-975-0975-dd06-07 ◽

2006 ◽

Vol 975 ◽

Cited By ~ 1

Author(s):

Yi Zhao ◽

Xin Zhang

Keyword(s):

Mechanical Properties ◽

Mechanical Behavior ◽

Measurement System ◽

Curing Agent ◽

Operational Parameters ◽

Crosslinking Process ◽

Sensing Applications ◽

Curvature Measurement ◽

The Relationship ◽

Mechanical Sensing

ABSTRACTThis paper reports mechanical properties evolution of polydimethylsiloxane (PDMS) during the crosslinking process. In this work, PDMS crosslinking was induced by mixing base prepolymer and curing agent at certain ratios. The liquid prepolymer was spun coated on a silicon wafer, and the curvature change of the wafer was measured continuously using a curvature measurement system. The relationship between the curvature change and typical mechanical properties was investigated using a bilayer model; and the evolution of the properties was derived, as a function of operational parameters. This work is expected to help better understanding of the crosslinking process and provide practical strategies for controlling the mechanical behavior of the resulting polymer structures, especially those for mechanical sensing applications.

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Highly Stretchable Polymer Optical Fiber for Mechanical Sensing in Artificial Tendons: Towards Novel Sensors for Soft Robotics

Actuators ◽

10.3390/act9040125 ◽

2020 ◽

Vol 9 (4) ◽

pp. 125

Author(s):

Arnaldo G. Leal-Junior ◽

Wagner Coimbra ◽

Carlos Marques ◽

Anselmo Frizera

Keyword(s):

Optical Fiber ◽

High Strain ◽

Polymerization Process ◽

Soft Robotics ◽

Polymer Optical Fiber ◽

Fiber Sensors ◽

Sensing Applications ◽

Highly Stretchable ◽

Novel Approaches ◽

Mechanical Sensing

The control of tendon-driven actuators is mainly affected by the tendon behavior under stress or strain. The measurement of these parameters on artificial tendons brings benefits on the control and novel approaches for soft robotics actuators. This paper presents the development of polymer optical fiber sensors fabricated through the light spinning polymerization process (LPS-POF) in artificial tendons. This fiber has exceptionally low Young’s modulus and high strain limits, suitable for sensing applications in soft structures. Two different configurations are tested, indicating the possibility of measuring strain and stress applied in the tendon with determination coefficients of 0.996 and 0.994, respectively.

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Printed Wheatstone bridge with embedded polymer based piezoresistive sensors for strain sensing applications

Additive Manufacturing ◽

10.1016/j.addma.2018.01.004 ◽

2018 ◽

Vol 20 ◽

pp. 119-125 ◽

Cited By ~ 16

Author(s):

H.F. Castro ◽

V. Correia ◽

N. Pereira ◽

P. Costab ◽

J. Oliveiraa ◽

...

Keyword(s):

Wheatstone Bridge ◽

Strain Sensing ◽

Piezoresistive Sensors ◽

Sensing Applications

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Ambulatory Activity Monitoring

European Psychologist ◽

10.1027/1016-9040.14.2.142 ◽

2009 ◽

Vol 14 (2) ◽

pp. 142-152 ◽

Cited By ~ 54

Author(s):

Johannes B.J. Bussmann ◽

Ulrich W. Ebner-Priemer ◽

Jochen Fahrenberg

Keyword(s):

Physical Activity ◽

Activity Monitoring ◽

Main Stream ◽

Computer Algorithms ◽

Ambulatory Activity ◽

Physiological Variables ◽

Piezoresistive Sensors ◽

Self Reports ◽

Recent Developments ◽

Objectively Measured

Behavior is central to psychology in almost any definition. Although observable activity is a core aspect of behavior, assessment strategies have tended to focus on emotional, cognitive, or physiological responses. When physical activity is assessed, it is done so mostly with questionnaires. Converging evidence of only a moderate association between self-reports of physical activity and objectively measured physical activity does raise questions about the validity of these self-reports. Ambulatory activity monitoring, defined as the measurement strategy to assess physical activity, posture, and movement patterns continuously in everyday life, has made major advances over the last decade and has considerable potential for further application in the assessment of observable activity, a core aspect of behavior. With new piezoresistive sensors and advanced computer algorithms, the objective measurement of physical activity, posture, and movement is much more easily achieved and measurement precision has improved tremendously. With this overview, we introduce to the reader some recent developments in ambulatory activity monitoring. We will elucidate the discrepancies between objective and subjective reports of activity, outline recent methodological developments, and offer the reader a framework for developing insight into the state of the art in ambulatory activity-monitoring technology, discuss methodological aspects of time-based design and psychometric properties, and demonstrate recent applications. Although not yet main stream, ambulatory activity monitoring – especially in combination with the simultaneous assessment of emotions, mood, or physiological variables – provides a comprehensive methodology for psychology because of its suitability for explaining behavior in context.

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Computer simulation study about the dependence of amorphous silicon photonic waveguides efficiency on the material quality

The European Physical Journal Applied Physics ◽

10.1051/epjap/2020190250 ◽

2020 ◽

Vol 90 (3) ◽

pp. 30502

Author(s):

Alessandro Fantoni ◽

João Costa ◽

Paulo Lourenço ◽

Manuela Vieira

Keyword(s):

Amorphous Silicon ◽

High Throughput Screening ◽

Simulation Analysis ◽

Low Cost ◽

Deposition Process ◽

Large Area ◽

Sidewall Roughness ◽

Sensing Applications ◽

Fabrication Defects ◽

The Impact

Amorphous silicon PECVD photonic integrated devices are promising candidates for low cost sensing applications. This manuscript reports a simulation analysis about the impact on the overall efficiency caused by the lithography imperfections in the deposition process. The tolerance to the fabrication defects of a photonic sensor based on surface plasmonic resonance is analysed. The simulations are performed with FDTD and BPM algorithms. The device is a plasmonic interferometer composed by an a-Si:H waveguide covered by a thin gold layer. The sensing analysis is performed by equally splitting the input light into two arms, allowing the sensor to be calibrated by its reference arm. Two different 1 × 2 power splitter configurations are presented: a directional coupler and a multimode interference splitter. The waveguide sidewall roughness is considered as the major negative effect caused by deposition imperfections. The simulation results show that plasmonic effects can be excited in the interferometric waveguide structure, allowing a sensing device with enough sensitivity to support the functioning of a bio sensor for high throughput screening. In addition, the good tolerance to the waveguide wall roughness, points out the PECVD deposition technique as reliable method for the overall sensor system to be produced in a low-cost system. The large area deposition of photonics structures, allowed by the PECVD method, can be explored to design a multiplexed system for analysis of multiple biomarkers to further increase the tolerance to fabrication defects.

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