Strain sensor

Maughan S.M., Kee H.H., Newson T.P., Simultaneous distributed fibre temperature and strain sensor using microwave coherent detection of spontaneous Brillouin backscatter, Meas. Sci. Technol. 2001 12 834-842. 

There are more issues and complexity to be considered if various micro-electromechanical (MEMS)-type devices are included in the macroelectronics tool kit. As described previously, the materials and devices required for TFTs and circuits can provide adequate electromagnetic (visible and RF) sensitivity for many image-type applications. These materials may also provide satisfactory performance in pressure and strain sensors. Nanotube/nanowire-based devices look promising for various chem-bio sensors.85 However, there is little that is known about the ability to integrate printed microfluidic devices (and other such devices with moving parts) into a roll-to-roll-type process. 

Xiao, H. Deng, J. Pickrell, G. May, R. G. Wang, A., Single crystal sapphire fiber based strain sensor for high temperature applications, J. Lightwave Technol. 2003, 21, 2276 2283... 

Strain hardening effect, 20 224 Straining efficiency, 77 340 Strain rate, 73 473 Strain recovery rate (Rr), in testing shape-memory polymers, 22 361 Strain sensors, 77 150, 151-152 Strain tensor, for noncentrosymmetry pont group crystals, 77 93-94 Strain versus time curve factors affecting, 73 473 material and microstructure effect on, 73 473-474... 

Gurau ef al. [129] presented another apparatus used to measure the in-plane viscous and inertial permeability coefficients. In their method, an annular DL sample was placed between an upper and lower fixture. The gas entered the upper fixture and was then forced fhrough fhe DL info fhe ouflef porfs (open to the atmosphere). A strain sensor was located in the upper fixture in order to determine the thickness of fhe DL (i.e., deformation) because fhe whole assembly was compressed to a determined pressure. In fhis mefhod, the flow rate, temperatures in both fixtures, and pressures were monitored in each test. Once the data were collected, the in-plane permeability was determined from the Forchheimer equation by application of fhe leasf squares fit analysis method. 

Case Study CNT-Based Strain Sensor Introduction... 

Trpkovski, S., Wade, S. A., Baxter, G. W. and Collins, S. F. (2003). Dual temperature and strain sensor using a combined fiber Bragg grating and fluorescence intensity ratio technique in Er[sup 3+]-doped fiber. Review cf... 

Kohler S et al (2000) Detection of 4-chlorobenzoate using immobilized recombinant Escherichia coli reporter strains. Sensor Actuator B-Chem 70(1-3) 139-144... 

Sagi E et al (2003) Fluorescence and bioluminescence reporter functions in genetically modified bacterial sensor strains. Sensor Actuator B-Chem 90(l-3) 2-8... 

Chaimanonart, N., Young, D. J. Remote RF powering system for wireless MEMS strain sensors, IEEE Sens.]., 6(2), 484M89 (2006). 

Fig. 6.12. Cross section of the organic semiconductor strain sensor [28]. Copyright 2005 IEEE...

The maximum process temperature used to fabricate the organic strain sensors is 110°C. The devices were tested using a Wheatstone bridge configuration and the results indicate that it is possible to fabricate a strain sensor at low temperatures with mechanical characteristics matched to low Young modulus supports using organic semiconductors. 

Joung et al. [29] have also demonstrated the possibility of combining these sensors with pentacene-based thin film transistors as temperature sensors. The strain sensor consists of a Wheatstone bridge structure where the pentacene film acts as sensing layer of a strain gauge, while the temperature sensors consist of bottom-contact pentacene transistors in which the variations of the drain currents in the subthreshold regime are measured with respect to temperature. 

Another relevant issue for sensors is packaging. In particular, for chemical sensors designed for working in solution, it is necessary to prevent the solution from any contact with the semiconductor layer (if this is not the sensitive layer of the device). Microfluidic systems [35,36] coupled with the sensor s active areas offer a valid solution to this problem because they allow the flow of the solution to the active area to be controlled and channeled, without compromising the semiconductor layer. For pressure/strain sensors the packaging should not compromise the mechanical flexibility of the whole structure. 

At present, the first attempts to develop strain sensors on garments are being made with piezoresistive stripes deposited on the garments [58-63]. The detection is made through piezoresistive tracks running on the fabric along, for example, a sleeve or parallel to the chest in a T-shirt. In this way, the movement results in a deformation of the track and in a variation of its resistance. No spatial resolution is achievable with such a strategy that is based on the measurement of the resistance of the whole track. The employment of OFETs could allow arrays and matrices to be built, so as to enable full spatial resolution (Fig. 6.23). 

As mentioned earlier, optical fibres with Bragg gratings can also be applied as pressure and strain sensors. When these fibres are integrated into a mattress or bed sheet, they will be deformed as soon as pressure is exerted on them. The deformation will cause proportional changes in the Bragg wavelength and, hence, the movement can be tracked (Dziuda and Skibniewski, 2014). 

Textile-based strain sensors have been demonstrated using stretch fabrics modified with inherently conductive polymers (Rovira et al., 2011) or carbon-loaded mbbers (Tognetti et al., 2005). Knitting with conductive yams is another approach to creating... 

Gerhard Troster s group, in ETH, Zurich, have also developed a prototype garment that can recognise upper body postures using textile strain sensors. A strain-sensitive fibre was made using a mixture of a thermoplastic elastomer and carbon black particles. 

Mattmann, C., Amft, O., Harms, H., Clemens, F., Troster, G., 2007. Recognizing upper body postures using textile strain sensors. In Proceedings of the 11th International Symposium on Wearable Computers (ISWC07), Boston, MA. 

G.M. Spinks, G.G. Wallace, L. Liu, and D. Zhou, Conducting polymers electromechanical actuators and strain sensors, Macromol. Symp., 192 (7th Pacific Polymer Conference, 2001), 161-169, (2003). 

Fiber optic sensors, e.g., fiber Bragg gratings (FBG) strain sensors... 

Kamath GM, Sundaram R, Gupta N, Rao MS. Damage studies in composite structures for structural health monitoring using strain sensors. Struct Health Monit Int J 2010 9(6) 497-512. http //dx.doi.org/10.1177/1475921710365391. 

Tracy M, Chang FK. Identifying impacts in composite plates with piezoelectric strain sensors, part I theory. J Intell Mater Syst Struct 1998 9(11) 920—8. 

Zhao P, Pisani D, L3mch CS. Piezoelectric strain sensor/actuator rosettes. Smart Mater Struct 2011 20(10) 102002. http //dx.doi.Org/10.1088/0964-1726/20/10/102002. Martin T, Hudd J, Wells P, Tunnichffe D, Das-Gupta D. The use of low profile piezoelectric sensors for impact and acoustic emission (AE) detection in CFRC structures. J Intell Mater Syst Struct 2001 12(8) 537—44. http //dx.doi.org/10.1177/ 10453890122145339. 

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