Scalable, high-performance magnetoelastic tags using frame-suspended hexagonal resonators

Tang, Jun; Green, Scott R.; Gianchandani, Yogesh B.

doi:10.1088/0960-1317/24/6/065006

Cited by 7 publications

(2 citation statements)

References 19 publications

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“…First, two separate transmit and receive coils can be placed perpendicular to each other to decouple them and remove any self-inductance effects [48]. Second, multiple thin-film magnetostrictive sensors can be packaged together to increase the signal-to-background ratio [49]. A magnetostrictive temperature sensor package can enable in situ near-field applications.…”

Section: Discussionmentioning

confidence: 99%

Design and analysis of magnetostrictive sensors for wireless temperature sensing

Rajagopal

Sinha

2021

Review of Scientific Instruments

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Magnetostrictive transducers are commonly used as actuators, sonar transducers, and in remote non-destructive evaluation. Their use in wireless thermometry is relatively unexplored.Since magnetostriction-based sensors are passive, they could potentially enable long-term nearfield thermometry. While the temperature sensitivity of resonance frequency in magnetostrictive transducers has been reported in previous studies, the origin of the temperature sensitivity has however not been elucidated. Here, we identify material properties that determine temperature sensitivity, and identify ways to improve sensitivity as well as the detection technique. Using a combination of analytical and computational methods, we systematically identify the material properties that directly influence the temperature coefficient of resonance frequency (TCF). We first experimentally measure the shift in resonance frequency due to temperature changes in a Metglas strip to be 0.03%K -1 . Using insights from theory, we then experimentally demonstrate a 5-fold improvement to the TCF by using Terfenol in place of Metglas as the magnetostrictive sensor material. We further demonstrate an alternate temperature sensing technique that does not require measuring the resonance frequency, consequently reducing instrument complexity. This work provides a general framework to analyze magnetostrictive materials and the sensing scheme for near-field wireless thermometry.

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Section: Discussionmentioning

confidence: 99%

Design and analysis of magnetostrictive sensors for wireless temperature sensing

Rajagopal

Sinha

2021

Review of Scientific Instruments

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“…Linear and rotary actuators have also been reported 8,9 , as have passive sensors that detect occlusions in biliary and peripheral artery stents 10,11 . Although most magnetoelastic devices are of the order of 1 cm in size in at least one dimension, tags as small as 1 mm have been reported 12,13 , demonstrating the degree of miniaturization that is possible with this technology.…”

Section: Introductionmentioning

confidence: 99%

Resonant magnetoelastic microstructures for wireless actuation of liquid flow on 3D surfaces and use in glaucoma drainage implants

2015

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Magnetoelastic resonators made from metal alloy foils are widely used for miniature wireless anti-theft tags and have also been explored for use in various sensing applications. Through annealing within three-dimensional (3D) molds, these foils can be formed into curved structures. Consequently, magnetoelastic materials present an opportunity for the development of a new class of wireless, actuators that have small form factors and low surface profiles and that can conform to curved surfaces. This paper describes passive, wireless, resonant magnetoelastic actuators intended for the generation of fluid flow on the surfaces of implantable Ahmed glaucoma drainage devices. The actuators are remotely excited to resonance using a magnetic field generated by external coils. The fluid flow is intended to limit cellular adhesion to the surface of the implant, as this adhesion can ultimately lead to implant encapsulation and failure. The actuators are micromachined from planar 29-μm-thick foils of Metglas 2826MB (Fe 40 Ni 38 Mo 4 B 18), an amorphous magnetoelastic alloy, using photochemical machining. Measuring 10.3 Â 5.6 mm 2 , the planar structures are annealed in 3D molds to conform to the surface of the drainage device, which has an aspherical curvature. Six actuator designs are described, with varying shapes and resonant mode shapes. The resonant frequencies for the different designs vary from 520 Hz to 4.7 kHz. Flow velocities of up to 266 μm s −1 are recorded at a wireless activation range of 25-30 mm, with peak actuator vibration amplitudes of 1.5 μm. Integrated actuators such as those described here have the potential to greatly enhance the effectiveness of glaucoma drainage devices at lowering eye pressure and may also be useful in other areas of medicine.

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Wireless strain measurement with a micromachined magnetoelastic resonator using ringdown frequency locking

Pepakayala

Green

Gianchandani

2017

ISSS J Micro Smart Syst

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Resonant magnetoelastic devices are widely used as anti-theft tags and are also being investigated for a range of sensing applications. The vast majority of magnetoelastic devices are operated at resonance, and rely upon an external interface to wirelessly detect the resonant frequency, and other characteristics. For micromachined devices, this detection method must accommodate diminished signal strength and elevated resonant frequencies. Feedthrough of the interrogating stimulus to the detector also presents a significant challenge. This paper describes a method of interrogating wireless magnetoelastic strain sensors using a new frequency-lock approach. Following a brief excitation pulse, the sensor ring-down is analyzed and a feedback loop is used to match the excitation frequency and the resonant frequency. Data acquisition hardware is used in conjunction with custom software to implement the frequency-lock loop. Advantages of the method include temporal isolation of interrogating stimulus from the sensor response and near real-time tracking of resonant frequencies. The method was investigated using a family of wireless strain sensors with resonant frequencies ranging from 120 to 240 kHz. Strain levels extending to 3.5 mstrain and sensitivities up to 14300 ppm/mstrain were measured with response times faster than 0.5 s. The standard deviation of the locked frequency did not exceed 0.1%.

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Scalable, high-performance magnetoelastic tags using frame-suspended hexagonal resonators

Cited by 7 publications

References 19 publications

Design and analysis of magnetostrictive sensors for wireless temperature sensing

Design and analysis of magnetostrictive sensors for wireless temperature sensing

Resonant magnetoelastic microstructures for wireless actuation of liquid flow on 3D surfaces and use in glaucoma drainage implants

Wireless strain measurement with a micromachined magnetoelastic resonator using ringdown frequency locking

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