A wireless strain sensor consumes less than 10 mW

Hasson

et al. 2016

J. Sens. Sens. Syst.

Abstract. Measuring air pressure using a capacitive pressure sensor is a robust and precise technique. In addition, a system that employs such transducers lies within the low power consumption applications such as wireless sensor nodes. In this article a high sensitivity with an elliptical diaphragm capacitive pressure sensor is proposed. This design was compared with a circular diaphragm in terms of thermal stresses and pressure and temperature sensitivity. The proposed sensor is targeted for tyre pressure monitoring system application. Altering the overlapping area between the capacitor plates by decreasing the effective capacitance area to improve the overall sensitivity of the sensor ( C/C), temperature sensitivity, and built-up stresses is also examined in this article. Theoretical analysis and finite element analysis (FEA) were employed to study pressure and temperature effects on the behaviour of the proposed capacitive pressure sensor. A MEMS (micro electro-mechanical systems) manufacturing processing plan for the proposed capacitive sensor is presented. An extra-low power short-range wireless read-out circuit suited for energy harvesting purposes is presented in this article. The developed read-out circuitry was tested in terms of sensitivity and transmission range.

Section: Surface Acoustic Wavementioning

confidence: 99%

A micro-capacitive pressure sensor design and modelling

Hasson

et al. 2016

J. Sens. Sens. Syst.

“…Strain measurement is one of the most widely measured quantities because this physical parameter can reveal the loading, fatigue, and material conditions of a structure [4,5]. Traditionally, foiled wire strain gauges are used to measure strains.…”

Section: Introductionmentioning

confidence: 99%

“…Although this method offers a reliable and inexpensive solution, the requirement of wiring for data and power transmission of the system limits its wide deployment within a structure. The associated circuit is also bulky and power hungry [1,4].…”

Section: Introductionmentioning

confidence: 99%

A multifunctional device as both strain sensor and energy harvester for structural health monitoring

et al. 2016

Abstract-In the context of wireless sensors (WSs) autonomous in energy, this paper presents a single macro-fiber composite (MFC) piezoelectric transducer which is used for the first time as a multifunctional device as both sensor and energy harvester in a time-multiplexing manner. The MFC is used as an energy harvester to charge up a storage capacitor. When there is sufficient energy, the WS is powered up and the MFC is used as a sensor. A circuit was implemented to harvest energy from the MFC and use the MFC as a sensor. Experiment validation shows that the MFC has an accuracy of up to 97 % as sensor and the circuit harvests energy from the MFC at its maximum power point with up to 98 % efficiency.

J. Microelectromech. Syst.

“…Powered sensors require a battery or an energy harvesting system or a combination of the two [2]. Passive sensors do not require an inbuilt power source.…”

Section: Introductionmentioning

confidence: 99%

Passive Wireless Strain Sensors Using Microfabricated Magnetoelastic Beam Elements

Pepakayala

Green

Gianchandani

2014

This paper describes resonant wireless strain sensors fabricated from magnetoelastic alloys. The transduction mechanism is the E effect-the change in stiffness of magnetoelastic materials with applied strain or magnetic field. This is measured as a shift in the resonant frequency and is detected wirelessly using pick-up coils utilizing the magnetoelastic coupling of these materials. The sensors are fabricated from a 28-μm-thick foil of Metglas 2826 MB (Fe 40 Ni 38 Mo 4 B 18 ), a ferromagnetic magnetoelastic alloy, using microelectrodischarge machining. Two sensor types are described-single and differential. The single sensor has an active area of 7 × 2 mm 2 , excluding the anchors. At 23°C, it operates at a resonant frequency of 230.8 kHz and has a sensitivity of 13 × 10 3 ppm/mstrain; the dynamic range is 0.05-1.05 mstrain. The differential sensor includes a strain independent reference resonator of area 2 × 0.5 mm 2 in addition to a sensing element of area 2.5 × 0.5 mm 2 that is divided into two segments. The sensor resonance is at 266.4 kHz and reference resonance is at 492.75 kHz. The differential sensor provides a dynamic range for 0-1.85 mstrain with a sensitivity of 12.5 × 10 3 ppm/mstrain at 23°C. The reference resonator of the differential sensor is used to compensate for the temperature dependence of the Young's modulus of Metglas 2826 MB, which is experimentally estimated to be −524 ppm/°C. For an increment of 35°C, uncompensated sensors exhibit a resonant frequency shift of up to 42% of the dynamic range for the single sensor and 30% of the dynamic range of the differential sensor, underscoring the necessity of temperature compensation. The geometry of both types of sensors can be modified to accommodate a variety of sensitivity and dynamic range requirements.[2013-0330] IndexTerms-Strain measurement, magnetoelasticity, resonant sensing, Metglas, E effect.