Integrated sensor based on acoustics-electricity-mechanics coupling effect for wireless passive gas detection

Integrated sensor combines multiple sensor functions into a single unit,which has the advantages of miniaturization and better application potential.However,limited by the sensing platforms of the sensor and the selectivity of the sensitive film,there are still challenges to realize multi-component gas detection in one unit.Herein,a principle integration method is proposed to achieve the multi-component gas detection based on the acoustics-electricity-mechanics coupling effect.The electrical and mechanical properties of the Bi_(2)S_(3)nanobelts materials in different atmospheres indicate the possibility of realizing the principle integration.At the same time,the surface acoustic wave(SAW)sensor as a multivariable physical transducer can sense both electrical and mechanical properties.Upon exposure to 10 ppm NO_(2),NH_(3),and their mixtures,the integrated SAW gas sensor shows a 4.5 kHz positive frequency shift(acoustoelectric effect),an 11 kHz negative frequency shift(mechanics effects),and a reduced 4 kHz negative frequency shift(acoustics-electricity-mechanics coupling effect),respectively.Moreover,we realize wireless passive detection of NO_(2)and NH_(3)based on the SAW sensor.Our work provides valuable insights that can serve as a guide to the design and fabrication of single sensors offering multi-component gas detection via different gas sensing mechanisms.

Wireless contactless pressure measurement of an LC passive pressure sensor with a novel antenna for high-temperature applications

In this paper, a novel antenna is proposed for high-temperature testing, which can make the high-temperature pressure characteristics of a wireless passive ceramic pressure sensor demonstrated at up to a temperature of 600℃. The design parameters of the antenna are similar to those of the sensor, which will increase the coupling strength between the sensor and testing antenna. The antenna is fabricated in thick film integrated technology, and the properties of the alumina ceramic and silver ensure the feasibility of the antenna in high-temperature environments. The sensor, coupled with the ceramic antenna, is investigated using a high-temperature pressure testing platform. The experimental measurement results show that the pressure signal in a harsh environment can be detected by the frequency diversity of the sensor.

Effect of Pyrolysis Temperature on Resonant Frequency of PDC-SiBCN Ceramic Based Wireless Passive Temperature Sensors

Wireless passive temperature sensors fabricated by polymer-derived SiBCN ceramic(PDC-SiBCN) pyrolyzed at different temperatures was studied.The resonant frequency of the sensors was measured in the temperature range of50 to 610℃.For the sensor made of the PDC-SiBCN pyrolyzed at 1000,1100 and 1200℃ individually,the resonant frequency decreased monotonically with developing the testing temperature.While for the sensor made of the PDC-SiBCN pyrolyzed at 1300℃,the resonant frequency showed a non-monotonic variation with testing temperature.The results suggest a possibility of tuning the resonant frequency of PDC-SiBCN based wireless passive temperature sensors by altering the pyrolysis temperature.

Strain transfer mechanism of passive wireless surface acoustic wave torque sensors using shear lag theory

A shear-lag theory was developed to investigate the strain transfer from the metal substrate to the surface acoustic wave （SAW） resonator through a bonding layer. A three-layer model of host structure-adhesive layer-resonator layer was established. The strain transfer was theoretically analyzed, and the main factors impacting the SAW sensor measurement were studied. The relationship between the sensor response and the individual effect of all these factors under static loads was discussed. Results showed that better accuracy could be achieved with increase in the adhesive stiffness or resonator length, or decrease in the adhesive thickness. The values of the strain transfer rate calculated from the analytical model agreed well with that from the available experiment data.

Passive wireless smart-skin sensor using RFID-based folded patch antennas

Folded patch antennas were investigated for the development of low-cost and wireless smart-skin sensors that monitor the strain in metallic structures.When the patch antenna is under strain/deformation,its resonance frequency varies accordingly.The variation can be easily interrogated and recorded by a wireless reader.The patch antenna adopts a specially chosen substrate material with low dielectric attenuation,as well as an inexpensive off-the-shelf radiofrequency identification(RFID)chip for signal modulation.Since the RFID chip harvests electromagnetic power from the interrogation signal emitted by the reader,the patch antenna itself does not require other(internal)power sources and,thus,serves as a battery-less(passive)and wireless strain sensor.In this preliminary investigation,a prototype folded patch antenna has been designed and manufactured.Tensile testing results show strong linearity between the interrogated resonance frequency and the strain experienced by the antenna.Through experiments,the strain sensing resolution is demonstrated to be under 50με,and the wireless interrogation distance is shown to be over a few feet for this preliminary prototype.

Development of a surface acoustic wave wireless and passive temperature sensor incorporating reflective delay line

based on optimal design on the core element of the sensor,a wireless and passive surface acoustic wave（SAW）temperature sensor integrated with ID Tag was presented.A reflective delay line,which consists of a transducer and eight reflectors on YZ LiNbO3 substrate.Was fabricated as the sensor element,in which,three reflectors were used for temperature sensing,and the other five were for the ID Tag using phase encoding.Single phase unidirectional transducers（SPUDTs）and shorted grating were used to structure the sAW device,leading to excellent signal to noise ratio（SNR）.The performance of the SAW device was simulated by the coupling of modes（COM）prior to fabrication.Using the network analyzer,the response in time domain of the fabricated 434 MHz SAW sensor was characterized,the measured S11 agrees well with the simulated one,sharp reflection peaks,high signal/noise,and low spurious noise between the reflection peaks were observed.Using the radar system based on FSCW as the reader unit.the developed SAW temperature sensors were evaluated wirelessly.Excellent1 inearity and good resolution of士1℃ were observed.

Real-time ultra-wideband video streaming in long-reach passive optical networks with wireless radiation in the 10 and 60 GHz bands

Real-time video streaming using ultra-wideband(UWB) technology is experimentally demonstrated along long-reach passive optical networks(LR-PONs) with different wired and wireless reaches. Experimental tests using external and direct modulation with UWB wireless radiation in the 10- and 60-GHz bands are performed. An ultra-bendable fiber is also considered for a last-mile distribution. The video quality at the output of the optical fiber infrastructure of the LR-PON is assessed using the error vector magnitude(EVM), and the link quality indicator(LQI) is used as a figure of merit after wireless radiation. An EVM below –17 dB is achieved for both externally and directly modulated LR-PONs comprising up to 125 km of optical fiber. EVM improvement is observed for longer LR-PONs when directly modulated lasers(DMLs) are used because of the amplitude gain provided by the combined effect of dispersion and DML's chirp. Compared with optical back-to-back operation, the LQI level degrades to the maximum around 20% for LR-PONs ranging between 75 and 125 km of fiber reach and with a wireless coverage of 2 m in the 10-GHz UWB band. The same level of LQI degradation is observed using the 60-GHz UWB band with a LR-PON integrating 101 km of access network, a last-mile distribution using ultra-bendable fiber, and a 5.2-m wireless link.

Resonance phenomena in dielectric media: A review and comparison of acoustic and electromagnetic modes

The theory and application of resonances and vibrational modes are part of the foundation of science.In this contribution,examples of acoustical resonators are highlighted,and compared to electromagnetic modes.As an example from architecture,we describe the phenomenon of whispering galleries;such modes are nowadays known in dielectric and optical resonators.A specimen of a semicircular whispering bench in Park Sanssouci in Potsdam is acoustically investigated and demonstrated to show low losses for sound propagation.A special acoustical bug is discussed which was used for the espionage of the U.S.ambassador in Moscow.The Sovyets could interrogate this passive device by radio waves.Its working principle was based on the electromagnetic resonance of the cavity that the sound-sensitive membrane was part of.The underlying relation between excitation and resonance is compared to the sound production in flue organ pipes.A stopped flue organ pipe was investigated using a piezoelectric film sensor inside the pipe body.The results show that even-numbered modes,which are usually suppressed in the radiated sound of a stopped pipe,are still present in the vibrations inside the resonator.