Flexible capacitive pressure sensor based on interdigital electrodes with porous microneedle arrays for physiological signal monitoring

Flexible pressure sensors have many potential applications in the monitoring of physiological signals because of their good biocompatibil-ity and wearability.However,their relatively low sensitivity,linearity,and stability have hindered their large-scale commercial application.Herein,aflexible capacitive pressure sensor based on an interdigital electrode structure with two porous microneedle arrays(MNAs)is pro-posed.The porous substrate that constitutes the MNA is a mixed product of polydimethylsiloxane and NaHCO3.Due to its porous and interdigital structure,the maximum sensitivity(0.07 kPa-1)of a porous MNA-based pressure sensor was found to be seven times higher than that of an imporous MNA pressure sensor,and it was much greater than that of aflat pressure sensor without a porous MNA structure.Finite-element analysis showed that the interdigital MNA structure can greatly increase the strain and improve the sensitivity of the sen-sor.In addition,the porous MNA-based pressure sensor was found to have good stability over 1500 loading cycles as a result of its bilayer parylene-enhanced conductive electrode structure.Most importantly,it was found that the sensor could accurately monitor the motion of afinger,wrist joint,arm,face,abdomen,eye,and Adam’s apple.Furthermore,preliminary semantic recognition was achieved by monitoring the movement of the Adam’s apple.Finally,multiple pressure sensors were integrated into a 33 array to detect a spatial pressure distribu-×tion.Compared to the sensors reported in previous works,the interdigital electrode structure presented in this work improves sensitivity and stability by modifying the electrode layer rather than the dielectric layer.

Toward Flexible and Wearable Embroidered Supercapacitors from Cobalt Phosphides-Decorated Conductive Fibers

Wearable supercapacitors(SCs)are gaining prominence as portable energy storage devices.To develop high-performance wearable SCs,the significant relationship among material,structure,and performance inspired us with a delicate design of the highly wearable embroidered supercapacitors made from the conductive fibers composited.By rendering the conductive interdigitally patterned embroidery as both the current collector and skeleton for the SCs,the novel pseudocapacitive material cobalt phosphides were then successfully electrodeposited,forming the first flexible and wearable in-plane embroidery SCs.The electrochemical measurements manifested that the highest specific capacitance was nearly 156.6 mF cm?2(65.72 F g?1)at the current density of 0.6 mA cm?2(0.25 A g?1),with a high energy density of 0.013 mWh cm?2(5.55 Wh kg?1)at a power density of 0.24 mW cm?2(100 W kg?1).As a demonstration,a monogrammed pattern was ingeniously designed and embroidered on the laboratory gown as the wearable in-plane SCs,which showed both decent electrochemical performance and excellent flexibility.

RF design and study of a 325 MHz 7 Me V APF IH-DTL for an injector of a proton medical accelerator

A compact interdigital H-mode drift-tube linac (IH-DTL) with the alternating-phase-focusing (APF) method, working at 325 MHz was designed for an injector of a proton medical accelerator. When fed in with a proper RF (radio frequency) power, the DTL cavity could establish the corresponding electromagnetic field to accelerate the ‘‘proton bunches’’ from an input energy of 3 MeV to an output energy of 7 MeV successfully, without any additional radial focusing elements. The gap-voltage distribution which was obtained from the CST■ Microwave Studio software simulations of the axial electric field was compared with that from the beam dynamics, and the errors met the requirements within ± 5%. In this paper, the RF design procedure and key results of the APF IH-DTL, which include the main RF characteristics of the cavity, frequency sensitivities of the tuners, and coupling factor of the RF power input coupler are presented.

FOULING DETECTION IN FOOD VESSELS USING INTERDIGITAL LAMB WAVE TRANSDUCER

Lamb waves are used to detect fouling in food vessels. The propagation of the Lamb waves in plates exhibits many modes and dispersion characteristics, which have great influence on fouling detection. The relative distribution of the in-plane and out-of-plane displacement of the mode across the thickness of the plate will determine the sensitivity of the mode to a particular loading condition. By considering the dispersion and multi-mode characteristics of guided waves, an interdigital polyvi- nylidene fluoride （PVDF） transducer is designed to realize the mode selection of gnided waves, and a single a0 mode is used for guided wave detection. Fouling detection experiments are conducted in the laboratory using epoxy adhesive on a thin plate. Using the interdigital PVDF transducer, three fouled areas are detected. Using one of the time-frequency analysis methods, the waveforms are further processed. This also demonstrates the validity of this method of fouling detection.

Focusing of Surface Acoustic Wave on a Piezoelectric Crystal

We investigate the focusing phenomena of a surface acoustic wave （SAW） field generated by a circular-arc interdigital transducer （IDT） on a piezoelectric crystal. A rigorous vector field theory of surface excitation on the crystal we developed previously is used to evaluate the convergent SAW field instead of the prevalent scalar angular spectrum used in optics. The theoretical results show that the anisotropy of a medium has great impact on the focusing properties of the acoustic beams, such as focal length and symmetrical distributions near the focus. A dark field method is used in experiment to observe the focusing of the SAW tield optically. Although the convergent phenomena of SAW field on the anisotropic media or piezoelectric crystals are very complicated, the experimental data are in agreement with those from the rigorous theory.

Chlorine Gas Sensors with HPS Film on Interdigitated Capacitors

The Cl2-sensitive heteropolysiloxanes(HPS) film was formed on the interdigital capacitor based on silicon dioxide by means of sol-gel process and spin-on technique.Measurements of interdigital capacitance were performed at room temperature for frequencies 100 Hz,1 kHz and 10 kHz.It is shown that there is a linear relationship between the capacitance and the concentration of chlorine gas.Influences of the measurement frequency and film thickness of silicate on the sensitivity of the sensor to C12 gas were discussed.And organically modified N,N-diethylaminopropyl-trimethoxysilane (APMS) had a much higher sensitivity.

Horizontal InAs nanowire transistors grown on patterned silicon-on-insulator substratea

High-density horizontal InAs nanowire transistors are fabricated on the interdigital silicon-on-insulator substrate.Hexagonal InAs nanowires are uniformly grown between face-to-face（111） vertical sidewalls of neighboring Si fingers by metal–organic chemical vapor deposition. The density of InAs nanowires is high up to 32 per group of silicon fingers,namely an average of 4 nanowires per micrometer. The electrical characteristics with a higher on/off current ratio of 2×10~5are obtained at room temperature. The silicon-based horizontal InAs nanowire transistors are very promising for future high-performance circuits.

Recent progress and challenges in interdigital microbatteries:Fabrication, functionalization and integration

Currently,the increasing demands for portable,implantable,and wearable electronics have triggered the interest in miniaturized energy storage devices.Different from conventional energy storage devices,interdigital microbatteries(IMBs) are free of separators and prepared on a single substrate,potentially achieving a short ionic diffusion path and better performance.Meanwhile,they can be easily fabricated and integrated into on-chip miniaturized electronics,holding the promise to provide long-lasting power for advanced microelectronic devices.To date,while many seminal works have been reviewed the topic of microbatteries,there is no work that systematically summarizes the development of IMBs of high energy density and stable voltage platforms from fabrication,functionalization to integration.The current review focuses on the most recent progress in IMBs,discussing advanced micromachining techniques with compatible features to construct high-performance IMBs with smart functions and intelligent integrated systems.The future opportunities and challenges of IMBs are also highlighted,calling for more efforts in this dynamic and fast-growing research field.

Digital Dermatitis in Dairy Cattle Is Still a Serious Problem in Western Europe

Bacterial infections are quite common in dairy cattle,and frequently related to internal organ systems like e.g.respiratory,intestinal and udder infections.Lameness in dairy cattle is mainly caused by both infectious and non-infectious hoof problems and these have different etiological background.At the moment(2018)the major infectious hoof disorders are DD(Digital Dermatitis)and IP(Interdigital Phlegmon).These are all due to infection from the area where dairy cows normally live and more or less intensive contact with“contaminated”manure.This paper gives insight in these different dermatitis problems cows are daily confronted with,with a focus on infectious hoof disorders as a more or less permanent problem in today’s dairy farming.

Pspice Equivalent Circuit Model for Implementation of Surface Acoustic Wave Filter

The crystals of quartz,lithium,and piezoelectric ceramics have a piezoelectric effect as their major characteristic.The surface acoustic wave filter(SAWF) was designed by using this property.However,the experimental cost of the fabrication of SAWF is higher than that of mechanical filter or LC filter.Through the RLC(resistor,inductor and capacitor) network equivalent circuit and the interdigital transducer(IDT) equivalent circuit model,the electromotive force,the mechanical impedance of piezoelectric plate,and the wave number of Mason circuit model were researched.The equivalent circuit can be used to reduce product development costs and shorten the development cycle.Comparing simulation result by Pspice software with the theory of SAWF,the simulated waveform is similar to theory measurement,and the equivalent circuit model is verified.

CEVA收购InterDigital的Hillcrest Labs智能传感器技术业务

并购吸纳的高度互补传感器处理技术已助力超1亿台设备,将扩展CEVA智能和互联技术产品组合CEVA,全球领先的智能和互联设备信号处理平台和人工智能处理器IP授权许可厂商(纳斯达克股票交易所代码:CEVA),宣布向InterDigital, Inc.收购Hillcrest Laboratories, Inc.(Hillcrest Labs)业务。Hillcrest Labs是消费电子产品和物联网(IoT)设备中传感器处理软件和组件的全球领先供应商。

Study on high-order frequency selective surface with interdigital capacitance loading

The application of frequency selection surfaces(FSSs)is limited by large area,narrow bandwidth,low stopband inhibition and large ripple in the passband.A method for designing high-order wide band miniaturized-element frequency selective surface(MEFSS)with capacitance loading is introduced.The proposed structure is composed of multiply sub-wavelength interdigital capacitance layer,sub-wavelength inductive wire grids separated by dielectric substrates.A simple equivalent circuit model,composed of short transmission lines coupled together with shunt inductors and capacitors,is presented for this structure.Using the equivalent circuit model and electromagnetic(EM)model,an analytical synthesis procedure is developed that can be used to synthesize the MEFSS from its desired system-level performance indicators such as the center frequency of operation,bandwidth and stopband inhibition.Using this synthesis procedure,a prototype of the proposed MEFSS with a third-order bandpass response,center frequency of 2.75 GHz,fractional bandwidth of 8%is designed,fabricated,and measured.The measurement results confirm the theoretical predictions and the design procedure of the structure and demonstrate that the proposed MEFSS has a stable frequency response with respect to the angle of incidence of the EM wave in the±30°range incidence,and the in-band return loss is greater than 18 dB,and the rejection in the stopband is greater than 25 dB at the frequency of 3.2 GHz.

Performance study of vertical MSM solar-blind photodetectorsbased onβ-Ga_(2)O_(3)thin film

In this work,β-Ga_(2)O_(3)thin films were grown on SiO_(2)substrate by atomic layer deposition(ALD)and annealed in N_(2)atmosphere to enhance the crystallization quality of the thin films,which were verified from X-rays diffraction(XRD).Based on the grownβ-Ga_(2)O_(3)thin films,vertical metal-semiconductor-metal(MSM)interdigital photodetectors(PDs)were fabricated and investigated.The PDs have an ultralow dark current of 1.92 pA,ultra-high photo-to-dark current ratio(PDCR)of 1.7×10^(6),and ultra-high detectivity of 4.25×10^(14)Jones at a bias voltage of 10 V under 254 nm deep ultraviolet(DUV).Compared with the horizontal MSM PDs under the same process,the PDCR and detectivity of the fabricated vertical PDs are increased by 1000 times and 100 times,respectively.In addition,the vertical PDs possess a high responsivity of 34.24 A/W and an external quantum efficiency of 1.67×10^(4)%,and also exhibit robustness and repeatability,which indicate excellent performance.Then the effects of electrode size and external irradiation conditions on the performance of the vertical PDs continued to be investigated.

Implementing wavelet transform with SAW elements

In the design of the finger-overlap envelope according to the envelope of wavelet func-tion, it is concluded that the pulse-response function of the interdigital transducer (IDT) for surface acoustic wave (SAW) is identical to the wavelet function. SAW type of the wavelet-transform ele-ment is manufactured. A new method of using two wavelet-transform elements to manufacture the reconstruction element of the wavelet transform is proposed. The sources of the element error are analyzed, and the methods for reducing the error are put forward. SAW type of the wavelet trans-formation element and its reconstruction element have the following three characteristics: (i) the implementing methods of the wavelet transform element and its reconstruction element are simple, and free of complicated mathematical algorithms of the wavelet transform; (ii) because one of SAW element is fast, the response velocities of SAW type of the wavelet transform element and its reconstruction element are also fast; (iii) the costs of the wavelet transform element and its recon-struction element are low, so the elements may be manufactured in a large quantity.

An ultra-sensitive and wide measuring range pressure sensor with paper-based CNT film/interdigitated structure

Flexible pressure sensors have attracted great attention due to their potential in the wearable devices market and in particular in human-machine interactive interfaces.Pressure sensors with high sensitivity,wide measurement range,and low-cost are now highly desired for such practical applications.In the present investigation,an ultrasensitive pressure sensor with wide measurement range has been successfully fabricated.Carbon nanotubes(CNTs)(uniformly sprayed on the surface of paper)comprise the sensitivity material,while lithographed interdigital electrodes comprise the substrate.Due to the synergistic effects of CNT’s high specific surface area,paper’s porous structure,interdigital electrodes’efficient contact with CNT,our pressure sensor realizes a wide measurement range from 0 to 140 kPa and exhibits excellent stability through 15,000 cycles of testing.For the paper-based CNT film/interdigitated structure(PCI)pressure sensor,the connection area between the sensitive material and interdigital electrodes dominates in the lowpressure region,while internal change within the sensitive materials plays the leading role in the high-pressure region.Additionally,the PCI pressure sensor not only displays a high sensitivity of 2.72 kPa–1(up to 35 kPa)but also can detect low pressures,such as that exerted by a resting mung bean(about 8 Pa).When attached to the surface of a human body,the pressure sensor can monitor physiological signals,such as wrist movement,pulse beats,or movement of throat muscles.Furthermore,the pressure sensor array can identify the spatial pressure distribution,with promising applications in humanmachine interactive interfaces.

Au modified ZnO nanowires for ethanol gas sensing

We demonstrated the application of sensors for ethanol gas detection.The ZnO nanowires based sensors with interdigital electrodes were fabricated,and a platform was constructed to test the properties of the sensors.To acquire better response and shorter response/recovery time,the ZnO nanowires were modified with Au.The ethanol gas sensing performance of the pure sensors and those modified with Au nanoparticles were investigated for comparison,and the optimal test temperature of 350℃ was obtained.We found that the response/recovery time for the modified sensor towards 500 ppm of the ethanol gas was reduced by 1.35 and1.42 times compared with the pure sensors,and the sensitivities towards 500 and 10 ppm of the ethanol gas were also increased by 3.18 and 1.35 times,respectively.These proved the enhancement of the Au nanoparticles in the ZnO nanowires based sensors for ethanol gas sensing.

Near-infrared metal-semiconductor-metal photodetector based on semi-insulating GaAs and interdigital electrodes

Metal-semiconductor-metal photodetectors on semi-insulating Ga As with interdigital electrodes showed significant enhancement in the spectral response in the near-infrared region as the electrode spacing is reduced. The photocurrent for the device with 5 μm interdigital spacing is five orders of magnitude higher than the dark current, and the room temperature detectivity is on the order of 2.4 × 1012cm Hz1∕2W-1at 5 V bias. Furthermore,the spectral response of this device possesses strong dependence on the polarization of incident light showing potential plasmonic effects with only microscale dimensions. These experimental data were analyzed using optical simulation to confirm the response of the devices.

通过柔性微针阵列集成的叉指电极装置产生电刺激用于癌症免疫治疗

免疫疗法通过化学或生物制剂来激活免疫系统,改变了癌症治疗的传统方式.但大多数免疫类药物在肿瘤组织内的渗透性差,容易产生副作用而使疗效不尽人意.电刺激疗法是一种新颖的癌症疗法,其可以不利用化学、生物制剂产生抑癌效果,但存在操作复杂和难以制备微米级小型电刺激装置的问题.本文通过将光学3D微打印技术与化学镀工艺结合,成功制备了柔性微针阵列集成的叉指电极装置.其能够生成交变电场触发肿瘤细胞内线粒体的钙离子过载和细胞内活性氧的产生,导致损伤相关分子模式释放,从而激活免疫应答并引起肿瘤免疫原性细胞死亡.实验结果显示,本文的通电微针装置具有良好的生物安全性和全身抑瘤作用,抑制了原发肿瘤和远处肿瘤的生长以及黑色素瘤肺转移.因此,本文将电刺激与免疫疗法相结合,为无药物癌症治疗提供了新方向并为癌症治疗领域提供了创新思路.

Novel 700 V high-voltage SOI LDMOS structure with folded drift region

A new high-voltage LDMOS with folded drift region （FDR LDMOS） is proposed. The drift region is folded by introducing the interdigital oxide layer in the： Si active layer, the result of which is that the effective length of the drift region is increased significantly. The breakdown characteristic has been improved by the shielding effect of the electric field from the holes accumulated in the surface of the device and the buried oxide layer. The numerical results indicate that the breakdown voltage of 700 V is obtained in the proposed device in comparison to 300 V of conventional LDMOS, while maintaining low on-resistance.

The outcome after using two different approaches for excision of Morton＇s neuroma

Background The choice for the surgical approach of interdigital neuroma in the foot is controversial.Plantar approach can leave a painful scar on weight bearing area; hence, some prefer dorsal approach.The aim of the current study was to measure the outcome of interdigital （Morton＇s） neurectomy performed by a single surgeon using dorsal and plantar approaches.Methods A retrospective review of the patient records of one orthopaedic foot and ankle surgeon identified thirty-six patients （42 feet） who had been treated operatively for a primary, persistently painful interdigital neuroma.The mean follow-up was 18 months.Pain, weight bearing, wound problems and rehabilitation period were studied.Results The duration to full weight bearing, return to work, driving and recreational activities were at least one week shorter in the dorsal group.The overall satisfaction for surgery was rated as excellent or good in 85% of the thirty six patients.Scar problems were more troublesome and common in the plantar group.There was residual numbness noticed in twenty feet, the pattern of numbness was quite variable and it was bothersome in only seven feet.There was one recurrence in the plantar group.Conclusions Resection of a symptomatic interdigital neuroma through a dorsal or a plantar approach can result in a good outcome.Dorsal approach, however, is associated with better rehabilitation and less scar problems.