Conformally integrated stent cell resonators for wireless monitoring of peripheral artery disease

This paper presents a thermoresponsive micro circuit breaker for biomedical applications specifically targeted at electronic intelligent implants. The circuit breaker is micromachined to have a shape-memory-alloy cantilever actuator as a normally closed temperature-sensitive switch to protect the device of interest from overheating, a critical safety feature for smart implants including those that are electrothermally driven with wireless micro heaters. The device is fabricated in a size of 1.5 × 2.0 × 0.46 mm3 using biocompatible materials and a chip-based titanium package, exhibiting a nominal cold-state resistance of 14 Ω. The breaker rapidly enters the full open condition when the chip temperature exceeds 63 °C, temporarily breaking the circuit of interest to lower its temperature until chip temperature drops to 51 °C, at which the breaker closes the circuit to allow current to flow through it again, physically limiting the maximum temperature of the circuit. This functionality is tested in combination with a wireless resonant heater powered by radio-frequency electromagnetic radiation, demonstrating self-regulation of heater temperature. The developed circuit-breaker chip operates in a fully passive manner that removes the need for active sensor and circuitry to achieve temperature regulation in a target device, contributing to the miniaturization of biomedical microsystems including electronic smart implants where thermal management is essential.

Section: Introductionmentioning

confidence: 99%

Biocompatible circuit-breaker chip for thermal management of biomedical microsystems

Luo

Dahmardeh

Takahata

2015

Section: Introductionmentioning

confidence: 99%

“…Hence, the acoustic wave sensor can sense the liquid mechanical properties directly [10]. Various applications based on the acoustic wave sensors have been successfully developed, such as chemical detection, mixture solution analysis and blood coagulation monitoring [10][11][12][13][14][15]. However, the main limitation of such acoustic wave sensors is that they are not able to differentiate a liquid's viscosity and density [16,17].…”

Section: Introductionmentioning

confidence: 99%

Viscosity and density decoupling method using a higher order Lamb wave sensor

Wang

Kropelnicki

et al. 2014

Viscosity and density are two important physical parameters of liquid. Such parameters are widely used for label-free chemical detection. Conventional technologies employ acoustic wave sensors to detect viscosity and density. In these sensors, the liquid under test directly contacts with the surface of the sensor. The produced acoustic wave in the sensor leaks to the adjacent liquid layer, causing a shift in the resonance frequency of the sensor. However, such sensors are not able to separately measure the viscosity and density because these two parameters jointly affect the shift of frequency. Although some indirect methods for decoupling these two parameters have been investigated, either dual-device or simultaneous measurement of frequency and attenuation is required. In this paper, a novel AlN based acoustic wave sensor is developed for decoupling viscosity and density. Multiple higher order modes of Lamb waves are generated in this sensor and employed to interact with the adjacent liquid under test. The frequency change of two unique modes (mode C and mode D) has been found in a linear relationship with viscosity and density, respectively. With this unique feature, viscosity and density of a liquid can be distinguished by a single device, which is promising for potential industrial applications, label-free chemical detection and clinical diagnosis.

“…In magnetoelastic devices, an applied magnetic field generates material strain that results in another magnetic field as a response, thereby allowing wireless interrogation [1][2][3][4][5]. The narrow-band response inherent to the resonant operation of such sensors limits interference from spurious sources.…”

Section: Introductionmentioning

confidence: 99%

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

Tang

Green

Gianchandani

2014

This paper presents the analysis, design and experimental evaluation of miniaturized magnetoelastic tags using frame-suspended hexagonal resonators. Magnetoelastic tags-also known as acousto-magnetic or magnetomechanical tags-are used in wireless detection systems-for example, electronic article surveillance and location mapping systems-that electromagnetically query the resonant response of the tags. In order to obtain a strong resonant response for miniaturized tags, a frame-suspended configuration is utilized to diminish the interaction between the vibrating portion of the tag and the substrate. The signal strength can be boosted by utilizing signal superposition with arrayed or clustered magnetoelastic tags. The hexagonal tags with a diameter of 1.3 mm are batch fabricated by photochemical machining from 27 μm thick Metglas TM 2826 MB, which is an amorphous NiFeMoB alloy. A preferred dc magnetic field bias for these tags is experimentally determined to be ≈31.5 Oe. A single frame-suspended magnetoelastic tag shows quality factors of 100-200. This design provides ≈75X improvement in signal amplitude compared to the non-suspended disc tag with similar size and resonant frequency. Across ten individual frame-suspended tags, the average resonant frequency is 2.13 MHz with a standard deviation of 0.44%, illustrating that this fabrication method provides repeatability. Linear signal superposition of the response has been experimentally measured for sets of frame-suspended tags that include as many as 500 units.