Flexible temperature sensor with high sensitivity ranging from liquid nitrogen temperature to 1200℃

Flexible temperature sensors have been extensively investigated due to their prospect of wide application in various flexible electronic products.However,most of the current flexible temperature sensors only work well in a narrow temperature range,with their application at high or low temperatures still being a big challenge.This work proposes a flexible thermocouple temperature sensor based on aerogel blanket substrate,the temperature-sensitive layer of which uses the screen-printing technology to prepare indium oxide and indium tin oxide.It has good temperature sensitivity,with the test sensitivity reaching 226.7μV℃^(−1).Most importantly,it can work in a wide temperature range,from extremely low temperatures down to liquid nitrogen temperature to high temperatures up to 1200℃,which is difficult to be achieved by other existing flexible temperature sensors.This temperature sensor has huge application potential in biomedicine,aerospace and other fields.

基于自解耦三明治结构的横向运动栅场效应晶体管MEMS微力传感器

本文介绍了一种基于横向可移动栅极场效应晶体管(LMGFET)的新型微型力传感器的开发。提出了一种精确的电气模型,用于小型LMGFET器件的性能评估,与以前的模型相比,其精度有所提高。采用了一种新型三明治结构,该结构由一个金交叉解耦栅阵列层和两个软光阻层SU-8组成。通过所提出的双差分传感结构,LMGFET横向工作在垂直干扰下的输出电流被大大消除,所提出传感器的相对输出误差从4.53%(传统差分结构)降低到0.01%。提出了一种实用的传感器制造工艺,并对其进行了模拟。基于LMGFET的力传感器的灵敏度为4.65μA·nN^(-1),可与垂直可移动栅极场效应晶体管(VMGFET)器件相媲美,但非线性度提高了0.78%,测量范围扩大了±5.10μN。这些分析为LMGFET器件的电气和结构参数提供了全面的设计优化,并证明了所提出的传感器在生物医学显微操作应用中具有良好的力传感潜力。

Wheel Setting Error Modeling and Compensation for Arc Envelope Grinding of Large-Aperture Aspherical Optics

Precision grinding is a key process for realizing the use of large-aperture aspherical optical elements in laser nuclear fusion devices,large-aperture astronomical telescopes,and high-resolution space cameras.In this study,the arc envelope grinding process of large-aperture aspherical optics is investigated using a CM1500 precision grinding machine with a maximum machinable diameter ofΦ1500 mm.The form error of the aspherical workpiece induced by wheel setting errors is analytically modeled for both parallel and cross grinding.Results show that the form error is more sensitive to the wheel setting error along the feed direction than that along the lateral direction.It is a bilinear function of the feed-direction wheel setting error and the distance to the optical axis.Based on the error function above,a method to determine the wheel setting error is proposed.Subsequently,grinding tests are performed with the wheels aligned accurately.Using a newly proposed partial error compensation method with an appropriate compensation factor,a form error of 3.4μm peak-to-valley(PV)for aΦ400 mm elliptical K9 glass surface is achieved.

Flexible pressure sensors with ultrahigh stress tolerance enabled by periodic microslits

Stress tolerance plays a vital role in ensuring the effectiveness of piezoresistive sensing films used in flexible pressure sensors.However,existing methods for enhancing stress tolerance employ dome-shaped,wrinkle-shaped,and pyramidal-shaped microstructures in intricate molding and demolding processes,which introduce significant fabrication challenges and limit the sensing performance.To address these shortcomings,this paper presents periodic microslits in a sensing film made of multiwalled carbon nanotubes and polydimethylsiloxane to realize ultrahigh stress tolerance with a theoretical maximum of 2.477 MPa and a sensitivity of 18.092 kPa−1.The periodic microslits permit extensive deformation under high pressure(e.g.,400 kPa)to widen the detection range.Moreover,the periodic microslits also enhance the sensitivity based on simultaneously exhibiting multiple synapses within the sensing interface and between the periodic sensing cells.The proposed solution is verified by experiments using sensors based on the microslit strategy for wind direction detection,robot movement sensing,and human health monitoring.In these experiments,vehicle load detection is achieved for ultrahigh pressure sensing under an ultrahigh pressure of over 400 kPa and a ratio of the contact area to the total area of 32.74%.The results indicate that the proposed microslit strategy can achieve ultrahigh stress tolerance while simplifying the fabrication complexity of preparing microstructure sensing films.

Multiple virus sorting based on aptamer-modified microspheres in a TSAW device

Due to the overlapping epidemiology and clinical manifestations of flaviviruses,differential diagnosis of these viral diseases is complicated,and the results are unreliable.There is perpetual demand for a simplified,sensitive,rapid and inexpensive assay with less cross-reactivity.The ability to sort distinct virus particles from a mixture of biological samples is crucial for improving the sensitivity of diagnoses.Therefore,we developed a sorting system for the subsequent differential diagnosis of dengue and tick-borne encephalitis in the early stage.We employed aptamer-modified polystyrene(PS)microspheres with different diameters to specifically capture dengue virus(DENV)and tick-borne encephalitis virus(TBEV),and utilized a traveling surface acoustic wave(TSAW)device to accomplish microsphere sorting according to particle size.The captured viruses were then characterized by laser scanning confocal microscopy(LSCM),field emission scanning electron microscopy(FE-SEM)and reverse transcription-polymerase chain reaction(RT‒PCR).The characterization results indicated that the acoustic sorting process was effective and damage-free for subsequent analysis.Furthermore,the strategy can be utilized for sample pretreatment in the differential diagnosis of viral diseases.

Optimizing strain response in lead-free(Bi_(0.5)Na_(0.5))TiO_(3)-BaTiO_(3)-NaNbO_(3)solid solutions via ferroelectric/(non-)ergodic relaxor phase boundary engineering

Lead-free bismuth sodium titanate(Bi_(0.5)Na_(0.5))TiO_(3)(BNT)and related solid solutions are potential piezoelectric materials for such applications as actuators and transducers if their excellent strain responses and piezoelectric properties can be optimized.In this work,a large strain response of 0.61%is achieved in lead-free(0.94-x%)(Bi_(0.5)Na_(0.5))TiO_(3)-0.06BaTiO_(3)-x%NaNbO_(3)(x=0 e6,BNT-6BT-xNN)ceramics with the composition of x=3.5 in a pseudo-cubic structure.Coexistence of ferroelectric(FE)and relaxor(RE)domain structures is observed in all the unpoled ceramics and the enhanced strain response is believed to be related to the evolution of the ergodic relaxor(ER)and non-ergodic(NR)states thanks to the substitution of antiferroelectric NN.BNT-6BT-3.5NN is a critical composition near the FE/NR/ER phase boundary close to room temperature(RT)and its high strain response arises from a synergistic combination of a reversible electric-field-induced phase transition and an active domain switching in the mixed NR/ER state.This work provides new insights into the dynamic interplay between mesoscopic domains and macroscopic electrical properties in the BNT-based piezoceramics.

A large-area bionic skin for high-temperature energy harvesting applications

For the large amount of waste heat wasted in daily life and industrial production,we propose a new type of flexible thermoelectric generators(F-TEGs)which can be used as a large area bionic skin to achieve energy harvesting of thermal energy.With reference to biological structures such as pinecone,succulent,and feathers,we have designed and fabricated a biomimetic flexible TEG that can be applied in a wide temperature range which has the highest temperature energy harvesting capability currently.The laminated free structure of the bionic F-TEG dramatically increases the efficiency and density of energy harvesting.The F-TEGs(single TEG only 101.2 mg in weight),without an additional heat sink,demonstrates the highest output voltage density of 286.1 mV/cm^(2)and the maximum power density is 66.5 mW/m^(2) at a temperature difference of nearly 1000℃.The flexible characteristics of F-TEGs make it possible to collect the diffused thermal energy by flexible attachment to the outer walls of high-temperature pipes and vessels of different diameters and shapes.This work shows a new design and application concept for flexible thermal energy collectors,which fills the gap of flexible energy harvesting in high-temperature environment.

A bionic approach for the mechanical and electrical decoupling of an MEMS capacitive sensor in ultralow force measurement

Capacitive sensors are efficient tools for biophysical force measurement,which is essential for the exploration of cellular behavior.However,attention has been rarely given on the influences of external mechanical and internal electrical interferences on capacitive sensors.In this work,a bionic swallow structure design norm was developed for mechanical decoupling,and the influences of structural parameters on mechanical behavior were fully analyzed and optimized.A bionic feather comb distribution strategy and a portable readout circuit were proposed for eliminating electrostatic interferences.Electrostatic instability was evaluated,and electrostatic decoupling performance was verified on the basis of a novel measurement method utilizing four complementary comb arrays and applicationspecific integrated circuit readouts.An electrostatic pulling experiment showed that the bionic swallow structure hardly moved by 0.770 nm,and the measurement error was less than 0.009% for the area-variant sensor and 1.118% for the gap-variant sensor,which can be easily compensated in readouts.The proposed sensor also exhibited high resistance against electrostatic rotation,and the resulting measurement error dropped below 0.751%.The rotation interferences were less than 0.330 nm and(1.829×10^(-7))°,which were 35 times smaller than those of the traditional differential one.Based on the proposed bionic decoupling method,the fabricated sensor exhibited overwhelming capacitive sensitivity values of 7.078 and 1.473 pF/μm for gap-variant and area-variant devices,respectively,which were the highest among the current devices.High immunity to mechanical disturbances was maintained simultaneously,i.e.,less than 0.369% and 0.058% of the sensor outputs for the gap-variant and area-variant devices,respectively,indicating its great performance improvements over existing devices and feasibility in ultralow biomedical force measurement.

Low-noise fluorescent detection of cardiac troponin I in human serum based on surface acoustic wave separation

Acute myocardial infarction(AMI)is a life-threatening disease when sudden blockage of coronary artery occurs.As the most specific biomarker,cardiac troponin I(cTnI)is usually checked separately to diagnose or eliminate AMI,and achieving the accurate detection of cTnI is of great significance to patients'life and health.Compared with other methods,fluorescent detection has the advantages of simple operation,high sensitivity and wide applicability.However,due to the strong fluorescence interference of biological molecules in body fluids,it is often difficult to obtain high sensitivity.In order to solve this problem,in this study,surface acoustic wave separation is designed to purify the target to achieve more sensitive detection performance of fluorescent detection.Specifically,the interference of background noise is almost completely removed on a microfluidic chip by isolating microbeads through acoustic radiation force,on which the biomarkers are captured by the immobilized detection probe.And then,the concentration of cTnI in human serum is detected by the fluorescence intensity change of the isolated functionalized beads.By this way,the detection limit of our biosensor calculated by 3σ/K method is 44 pg/mL and 0.34 ng/mL in PBS buffer and human serum respectively.Finally,the reliability of this method has been validated by comparison with clinical tests from the nephelometric analyzer in hospital.

Highly sensitive flexible heat flux sensor based on a microhole array for ultralow to high temperatures

With the growing demand for thermal management of electronic devices,cooling of high-precision instruments,and biological cryopreservation,heat flux measurement of complex surfaces and at ultralow temperatures has become highly imperative.However,current heat flux sensors(HFSs)are commonly used in high-temperature scenarios and have problems when applied in low-temperature conditions,such as low sensitivity and embrittlement.In this study,we developed a flexible and highly sensitive HFS that can operate at ultralow to high temperatures,ranging from−196°C to 273°C.The sensitivities of HFSs with thicknesses of 0.2 mm and 0.3 mm,which are efficiently manufactured by the screen-printing method,reach 11.21μV/(W/m2)and 13.43μV/(W/m2),respectively.The experimental results show that there is a less than 3%resistance change from bending to stretching.Additionally,the HFS can measure heat flux in both exothermic and absorptive cases and can measure heat flux up to 25 kW/m2.Additionally,we demonstrate the application of the HFS to the measurement of minuscule heat flux,such as heat dissipation of human skin and cold water.This technology is expected to be used in heat flux measurements at ultralow temperatures or on complex surfaces,which has great importance in the superconductor and cryobiology field.

Highly sensitive piezoresistive and thermally responsive fibrous networks from the in situ growth of PEDOT on MWCNT-decorated electrospun PU fibers for pressure and temperature sensing

Flexible electronics have demonstrated various strategies to enhance the sensory ability for tactile perception and wearable physiological monitoring.Fibrous microstructures have attracted much interest because of their excellent mechanical properties and fabricability.Herein,a structurally robust fibrous mat was first fabricated by electrospinning,followed by a sequential process of functionalization utilizing ultrasonication treatment and in situ polymerization growth.Electrospun polyurethane(PU)microfibers were anchored with multi-walled carbon nanotubes(MWCNTs)to form conductive paths along each fiber by a scalable ultrasonic cavitation treatment in an MWCNT suspension.After,a layer of poly(3,4-ethylene dioxythiophene)(PEDOT)was grown on the surface of PU fibers decorated with MWCNTs to enhance the conductive conjunctions of MWCNTs.Due to the superior electromechanical behaviors and mechanical reinforcement of PEDOT,the PEDOT/MWCNT@PU mat-based device exhibits a wide working range(0–70 kPa),high sensitivity(1.6 kPa−1),and good mechanical robustness(over 18,000 cycles).The PEDOT/MWCNT@PU mat-based sensor also demonstrates a good linear response to different temperature variations because of the thermoelectricity of the PEDOT/MWCNT composite.This novel strategy for the fabrication of multifunctional fibrous mats provides a promising opportunity for future applications for high-performance wearable devices.

Advances in high-performance MEMS pressure sensors:design,fabrication,and packaging

Pressure sensors play a vital role in aerospace,automotive,medical,and consumer electronics.Although microelectromechanical system(MEMS)-based pressure sensors have been widely used for decades,new trends in pressure sensors,including higher sensitivity,higher accuracy,better multifunctionality,smaller chip size,and smaller package size,have recently emerged.The demand for performance upgradation has led to breakthroughs in sensor materials,design,fabrication,and packaging methods,which have emerged frequently in recent decades.This paper reviews common new trends in MEMS pressure sensors,including minute differential pressure sensors(MDPSs),resonant pressure sensors(RPSs),integrated pressure sensors,miniaturized pressure chips,and leadless pressure sensors.To realize an extremely sensitive MDPS with broad application potential,including in medical ventilators and fire residual pressure monitors,the“beam-membrane-island”sensor design exhibits the best performance of 66μV/V/kPa with a natural frequency of 11.3 kHz.In high-accuracy applications,silicon and quartz RPS are analyzed,and both materials show±0.01%FS accuracy with respect to varying temperature coefficient of frequency(TCF)control methods.To improve MEMS sensor integration,different integrated“pressure+x”sensor designs and fabrication methods are compared.In this realm,the intercoupling effect still requires further investigation.Typical fabrication methods for microsized pressure sensor chips are also reviewed.To date,the chip thickness size can be controlled to be<0.1 mm,which is advantageous for implant sensors.Furthermore,a leadless pressure sensor was analyzed,offering an extremely small package size and harsh environmental compatibility.This review is structured as follows.The background of pressure sensors is first presented.Then,an in-depth introduction to MEMS pressure sensors based on different application scenarios is provided.Additionally,their respective characteristics and significant advancements are analyzed and summarized.Finally,development trends of MEMS pressure sensors in different fields are analyzed.

Noninvasive fluid bubble detection based on capacitive micromachined ultrasonic transducers

Ultrasonic fluid bubble detection is important in industrial controls,aerospace systems and clinical medicine because it can prevent fatal mechanical failures and threats to life.However,current ultrasonic technologies for bubble detection are based on conventional bulk PZT-based transducers,which suffer from large size,high power consumption and poor integration with ICs and thus are unable to implement real-time and long-term monitoring in tight physical spaces,such as in extracorporeal membrane oxygenation(ECMO)systems and dialysis machines or hydraulic systems in aircraft.This work highlights the prospect of capacitive micromachined ultrasonic transducers(CMUTs)in the aforementioned application situations based on the mechanism of received voltage variation caused by bubble-induced acoustic energy attenuation.The corresponding theories are established and well validated using finite element simulations.The fluid bubbles inside a pipe with a diameter as small as 8 mm are successfully measured using our fabricated CMUT chips with a resonant frequency of 1.1 MHz.The received voltage variation increases significantly with increasing bubble radii in the range of 0.5–2.5 mm.Further studies show that other factors,such as bubble positions,flow velocities,fluid medium types,pipe thicknesses and diameters,have negligible effects on fluid bubble measurement,demonstrating the feasibility and robustness of the CMUT-based ultrasonic bubble detection technique.

Monolithically integrated triaxial high-performance micro accelerometers with position-independent pure axial stressed piezoresistive beams

With the increasing demand for multidirectional vibration measurements,traditional triaxial accelerometers cannot achieve vibration measurements with high sensitivity,high natural frequency,and low cross-sensitivity simultaneously.Moreover,for piezoresistive accelerometers,achieving pure axial deformation of the piezoresistive beam can greatly improve performance,but it requires the piezoresistive beam to be located in a specific position,which inevitably makes the design more complex and limits the performance improvement.Here,a monolithically integrated triaxial high-performance accelerometer with pure axial stress piezoresistive beams was designed,fabricated,and tested.By controlling synchronous displacements at both piezoresistive beam ends,the pure axial stress states of the piezoresistive beams could be easily achieved with position independence without tedious calculations.The measurement unit for the z-axis acceleration was innovatively designed as an interlocking proof mass structure to ensure a full Wheatstone bridge for sensitivity improvement.The pure axial stress state of the piezoresistive beams and low cross-sensitivity of all three units were verified by the finite element method(FEM).The triaxial accelerometer was fabricated and tested.Results showing extremely high sensitivities(x axis:2.43 mV/g/5 V;y axis:2.44 mv/g/5 V;z axis:2.41 mV/g/5 V(without amplification by signal conditioning circuit))and high natural frequencies(x/y axes:11.4 kHz;z-axis:13.2 kHz)were obtained.The approach of this paper makes it simple to design and obtain high-performance piezoresistive accelerometers.

高端精密装备精度测量基础理论与方法

完整而精确的测量信息获取是装备设计优化、制造过程调控和服役状态保持的基础,是实现重大装备“上水平”“高性能”的内在要素。本文分析了我国高端精密装备精度测量基础理论发展所面临的重大需求挑战,总结了当前高端精密装备制造精度测量理论、方法与技术领域的主要进展,凝炼了该领域未来5~10年的重大关键科学问题,探讨了前沿研究方向和科学基金资助战略。

Novel resonant pressure sensor based on piezoresistive detection and symmetrical in-plane mode vibration

In this paper,a novel resonant pressure sensor is developed based on electrostatic excitation and piezoresistive detection.The measured pressure applied to the diaphragm will cause the resonant frequency shift of the resonator.The working mode stress–frequency theory of a double-ended tuning fork with an enhanced coupling beam is proposed,which is compatible with the simulation and experiment.A unique piezoresistive detection method based on small axially deformed beams with a resonant status is proposed,and other adjacent mode outputs are easily shielded.According to the structure design,high-vacuum wafer-level packaging with different doping in the anodic bonding interface is fabricated to ensure the high quality of the resonator.The pressure sensor chip is fabricated by dry/wet etching,high-temperature silicon bonding,ion implantation,and wafer-level anodic bonding.The results show that the fabricated sensor has a measuring sensitivity of~19 Hz/kPa and a nonlinearity of 0.02%full scale in the pressure range of 0–200 kPa at a full temperature range of−40 to 80°C.The sensor also shows a good quality factor>25,000,which demonstrates the good vacuum performance.Thus,the feasibility of the design is a commendable solution for high-accuracy pressure measurements.

Fast frequency relocking for synchronization enhanced resonant accelerometer

Synchronization,as a unique phenomenon,has been extensively studied in biology,chaotic systems,nonlinear dynamics,quantum information,and other fields.Benefiting from the characteristics of frequency amplification,noise suppression,and stability improvement,synchronization has been gradually applied in sensing,communication,time keeping,and other applications.In the sensing field,synchronization provides a new strategy to improve the performance of sensors.However,the performance improvement is only effective within the synchronization range,and the narrow synchronization range has become a great challenge for the wide application of synchronizationenhanced sensing mechanism.Here,we propose a frequency automatic tracking system(FATS)to widen the synchronization range and track the periodic acceleration signals by adjusting the frequency of the readout oscillator in real time.In addition,a high-precision frequency measurement system and fast response control system based on FPGA(Field Programmable Gate Array)are built,and the tracking performance of the FATS for static and dynamic external signals is analyzed to obtain the optimal control parameters.Experimental results show that the proposed automatic tracking system is capable of static acceleration measurement,the synchronization range can be expanded to 975 Hz,and the relocking time is shortened to 93.4 ms at best.By selecting the optimal PID parameters,we achieve a faster relocking time to meet the requirements of low-frequency vibration measurements,such as seismic detection and tidal monitoring.

Advanced tools and methods for single-cell surgery

Highly precise micromanipulation tools that can manipulate and interrogate cell organelles and components must be developed to support the rapid development of new cell-based medical therapies,thereby facilitating in-depth understanding of cell dynamics,cell component functions,and disease mechanisms.This paper presents a literature review on micro/nanomanipulation tools and their control methods for single-cell surgery.Micromanipulation methods specifically based on laser,microneedle,and untethered micro/nanotools are presented in detail.The limitations of these techniques are also discussed.The biological significance and clinical applications of single-cell surgery are also addressed in this paper.

Programmable synchronization enhanced MEMS resonant accelerometer

Acceleration measurement is of great significance due to its extensive applications in military/industrial fields.In recent years,scientists have been pursuing methods to improve the performance of accelerometers,particularly through seeking new sensing mechanisms.Herein,we present a synchronized oscillator-based enhancement approach to realize a fivefold resolution improvement of a microelectromechanical resonant accelerometer.Through the unidirectional electrical coupling method,we achieved synchronization of the sensing oscillator of the microelectromechanical resonant accelerometer and an external reading oscillator,which remarkably enhanced the stability of the oscillation system to 19.4 ppb and the resolution of the accelerometer to 1.91μg.In addition,the narrow synchronization bandwidth of conventional synchronized oscillators was discussed,and hence,we propose a novel frequency automatic tracking system to expand the synchronization bandwidth from 113 to 1246 Hz,which covers the full acceleration measurement range of±1 g.For the first time,we utilized a unidirectional electrical synchronization mechanism to improve the resolution of resonant sensors.Our comprehensive scheme provides a general and powerful solution for performance enhancement of any microelectromechanical system(MEMS)resonant sensor,thereby enabling a wide spectrum of applications.

Piezoresistive pressure sensor with high sensitivity for medical application using peninsula-island structure

Abstract A novel micro-electromechanical systems piezoresistive pressure sensor with a diagonally positioned peninsula-island structure has high sensitivity for ultra- low-pressure measurement. The pressure sensor was designed with a working range of 0-500 Pa and had a high sensitivity of 0.06 mV-V^-1-Pa-1. The trade-off between high sensitivity and linearity was alleviated. Moreover, the influence of the installation angle on the sensing chip output was analyzed, and an application experiment of the sensor was conducted using the built pipettor test platform. Findings indicated that the proposed pressure sensor had sufficient resolution ability and accuracy to detect the pressure variation in the pipettor chamber. Therefore, the proposed pressure sensor has strong potential for medical equipment application.