Microfabrication of spray-coated SWCNT film strain gauges

AbstractThere is an emergent demand for high-flexibility, high-sensitivity and low-power strain gauges capable of sensing small deformations and vibrations in extreme conditions. Enhancing the gauge factor remains one of the greatest challenges for strain sensors. This is typically limited to below 300 and set when the sensor is fabricated. We report a strategy to tune and enhance the gauge factor of strain sensors based on Van der Waals materials by tuning the carrier mobility and concentration through an interplay of piezoelectric and photoelectric effects. For a SnS2 sensor we report a gauge factor up to 3933, and the ability to tune it over a large range, from 23 to 3933. Results from SnS2, GaSe, GeSe, monolayer WSe2, and monolayer MoSe2 sensors suggest that this is a universal phenomenon for Van der Waals semiconductors. We also provide proof of concept demonstrations by detecting vibrations caused by sound and capturing body movements.

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Comparison of Resistive and Optical Strain Measurement for Early Fracture Detection

Current Directions in Biomedical Engineering ◽

10.1515/cdbme-2020-3050 ◽

2020 ◽

Vol 6 (3) ◽

pp. 196-199

Author(s):

Alina Carabello ◽

Constanze Neupetsch ◽

Michael Werner ◽

Christian Rotsch ◽

Welf-Guntram Drossel ◽

...

Keyword(s):

Surgical Training ◽

Error Detection ◽

Strain Measurement ◽

Testing Machine ◽

Image Correlation ◽

Strain Gauges ◽

Measurement Technology ◽

Bone Surface ◽

Fracture Detection ◽

Local Strains

AbstractTo increase learning success in surgical training, physical simulators are supplemented by measurement technology to generate and record objective feedback and error detection. An opportunity to detect fractures following hip stem implantation early can be measurement of occurring strains on bone surface. These strains can be determined while using strain gauges, digital image correlation (DIC) or photoelasticity. In this research strain gauges and DIC were compared regarding their suitability as strain measurement tools for use in physical simulators. Therefore a testing method was described to replicate the implantation of a hip stem. Testing devices modelled on a realistic prosthesis were pressed into prepared porcine femora in a two-step procedure with a material testing machine. The local strains occurring on bone surface were determined using an optical measurement system for DIC and strain gauges. The initial fractures in the tested femora are located medial-anterior in most cases (73,6%). With increasing indentation depth of the test device, the strains on bone surface increase. Comparing the local strains determined by DIC and strain gauges consistencies in curves are noticeable. Maximal determined strains before fracturing amount to 0,69% with strain gauges and 0,75% with DIC. In the range of the fracture gap, strain gradients are determined by using DIC. However the detected surfaces are of low quality caused by gaps and motion artefacts. The results show strains on bone surfaces for early fracture detection are measurable with strain gauges and DIC. DIC is assessed as less suitable compared to strain gauges. Furthermore strain gauges have greater level of integration and economic efficiency, so they are preferred the use in surgical training simulators.

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Dentinal microcracks induced by endodontic procedures: suggested design for experimental studies using micro-CT and strain gauges

Journal of Endodontics ◽

10.1016/j.joen.2021.04.016 ◽

2021 ◽

Author(s):

Stéphanie Quadros Tonelli ◽

Marcelo Avelar Antunes ◽

Kênia Maria Soares de Toubes ◽

Antônio Carlos de Oliveira Miranda ◽

André Maués Brabo Pereira ◽

...

Keyword(s):

Experimental Studies ◽

Strain Gauges ◽

Micro Ct

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Optical strain measurements on fast moving fiber reinforced polymer rotors using diffraction gratings

tm - Technisches Messen ◽

10.1515/teme-2019-0010 ◽

2019 ◽

Vol 86 (3) ◽

pp. 175-183

Author(s):

Julian Lich ◽

Tino Wollmann ◽

Angelos Filippatos ◽

Maik Gude ◽

Robert Kuschmierz ◽

...

Keyword(s):

Rigid Body ◽

Strain Measurement ◽

Composite Structures ◽

Dynamical Behavior ◽

Image Correlation ◽

Fiber Reinforced Polymers ◽

Strain Gauges ◽

Objective Lens ◽

Fiber Reinforced ◽

Body Movements

AbstractIn-situ measurements of the deformation and of the structural dynamical behavior of moving composite structures, such as rotors made of glass fiber reinforced polymers (GFRP), are necessary in order to validate newly developed simulation models. Local methods like strain gauges and fiber Bragg gratings lack spatial resolution, while contactless optical methods like image correlation or speckle interferometry suffer from noise effects in the presence of fast rigid body movements. A novel compact sensor – based on the diffraction grating method – is introduced for spatially and temporally resolved strain measurement. The use of a line camera allows the measurement of vibrations up to several tens of kHz. With a scanning movement, strain fields at submillimeter resolution can be recorded. The use of two diffraction orders and an objective lens reduces cross sensitivities to rigid body movements on the strain measurement by two to three orders of magnitude. A validation on a GFRP probe was conducted in a quasi-static tensile test with an optical extensometer up to 14500 µϵ. Furthermore, a strain measurement on a moving rotor at surface speeds up to 75 m/s was performed and the results were compared with those of strain gauges as a gold standard. The statistical standard deviation was around 10 µϵ and independent of the rotational speed.

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The effect of frog pressure and downward vertical load on hoof wall weight-bearing and third phalanx displacement in the horse - an in vitro study : research communication

Journal of the South African Veterinary Association ◽

10.4102/jsava.v72i4.656 ◽

2001 ◽

Vol 72 (4) ◽

Cited By ~ 1

Author(s):

A. Olivier ◽

J. Wannenburg ◽

R.D. Gottschalk ◽

M.J. Van der Linde ◽

H.T. Groeneveld

Keyword(s):

Solar Surface ◽

Weight Bearing ◽

Testing Machine ◽

Vertical Component ◽

In Vitro Study ◽

Vitro Study ◽

Total Weight ◽

Strain Gauges ◽

Tensile Testing Machine

A shoe was designed to combine the advantages of a reverse shoe and an adjustable heart bar shoe in the treatment of chronic laminitis. This reverse even frog pressure (REFP) shoe applies pressure uniformly over a large area of the frog solar surface. Pressure is applied vertically upward parallel to the solar surface of the frog and can be increased or decreased as required. Five clinically healthy horses were humanely euthanased and their dismem-bered forelimbs used in an in vitro study. Frog pressure was measured by strain gauges applied to the ground surface of the carrying tab portion of the shoe. A linear variable distance transducer (LVDT) was inserted into a hole drilled in the dorsal hoof wall. The LVDT measured movement of the third phalanx (P3) in a dorsopalmar plane relative to the dorsal hoof wall. The vertical component of hoof wall compression was measured by means of unidirectional strain gauges attached to the toe, quarter and heel of the medial hoof wall of each specimen. The entire limb was mounted vertically in a tensile testing machine and submitted to vertical downward compressive forces of 0 to 2500 Nat a rate of 5 cm/minute. The effects of increasing frog pressure on hoof wall weight-bearing and third phalanx movement within the hoof were determined. Each specimen was tested with the shoe under the following conditions: zero frog pressure; frog pressure used to treat clinical cases of chronic laminitis (7 N-cm); frog pressure clinically painful to the horse as determined prior to euthanasia; frog pressure just alleviating this pain. The specimens were also tested after shoe removal. Total weight-bearing on the hoof wall at zero frog pressure was used as the basis for comparison. Pain-causing and pain-alleviating frog pressures decreased total weight-bearing on the hoof wall (P < 0.05). Frog pressure of 7 N-cm had no statistically significant effect on hoof wall weight-bearing although there was a trend for it to decrease as load increased. Before loading, the pain-causing and pain-alleviating frog pressures resulted in a palmar movement of P3 relative to the dorsal hoof wall compared to the position of P3 at zero frog pressure (P < 0.05). This difference remained statistically significant up to 1300 Nload. At higher loads, the position of P3 did not differ significantly for the different frog pressures applied. It is concluded that increased frog pressure using the REFP shoe decreases total hoof wall weight-bearing and causes palmar movement of P3 at low weight-bearing loads. Without a shoe the toe and quarter hoof wall compression remained more constant and less in magnitude, than with a shoe.

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