Microarrow sensor array with enhanced skin adhesion for transdermal continuous monitoring of glucose and reactive oxygen species

Conventional blood sampling for glucose detection is prone to cause pain and fails to continuously record glucose fluctuations in vivo.Continuous glucose monitoring based on implantable electrodes could induce pain and potential tissue inflammation,and the presence of reactive oxygen species(ROS)due to inflammationmay affect glucose detection.Microneedle technology is less invasive,yet microneedle adhesion with skin tissue is limited.In this work,we developed a microarrow sensor array(MASA),which provided enhanced skin surface adhesion and enabled simultaneous detection of glucose and H_(2)O_(2)(representative of ROS)in interstitial fluid in vivo.The microarrows fabricated via laser micromachining were modified with functional coating and integrated into a patch of a three-dimensional(3D)microneedle array.Due to the arrow tip mechanically interlocking with the tissue,the microarrow array could better adhere to the skin surface after penetration into skin.The MASA was demonstrated to provide continuous in vivo monitoring of glucose and H_(2)O_(2) concentrations,with the detection of H_(2)O_(2) providing a valuable reference for assessing the inflammation state.Finally,the MASA was integrated into a monitoring system using custom circuitry.This work provides a promising tool for the stable and reliable monitoring of blood glucose in diabetic patients.

Direct-Ink-Writing Printed Strain Rosette Sensor Array with Optimized Circuit Layout

The full-field multiaxial strain measurement is highly desired for application of structural monitoring but still challenging,especially when the manufacturing and assembling for largearea sensing devices is quite difficult.Compared with the traditional procedure of gluing commercial strain gauges on the structure surfaces for strain monitoring,the recently developed Direct-Ink-Writing(DIW)technology provides a feasible way to directly print sensors on the structure.However,there are still crucial issues in the design and printing strategies to be probed and improved.Therefore,in this work,we propose an integrated strategy from layered circuit scheme to rapid manufacturing of strain rosette sensor array based on the DIW technology.Benefit from the innovative design with simplified circuit layout and the advantages of DIW for printing multilayer structures,here we achieve optimization design principle for strain rosette sensor array with scalable circuit layout,which enable a hierarchical printing strategy for multiaxial strain monitoring in large scale or multiple domains.The strategy is highly expected to adapt for the emerging requirement in various applications such as integrated soft electronics,nondestructive testing and small-batch medical devices.

Low-Complexity DOA Estimation of Noncircular Signals for Coprime Sensor Arrays

This paper presents a low?complexity method for the direction?of?arrival(DOA)estimation of noncircular signals for coprime sensor arrays.The noncircular property is exploited to improve the performance of DOA estimation.To reduce the computational complexity,the rotational invariance propagator method(RIPM)is included in the algorithm.First,the extended array output is reconstructed by combining the array output and its conjugated counterpart.Then,the RIPM is utilized to obtain two sets of DOA estimates for two subarrays.Finally,the true DOAs are estimated by combining the consistent results of the two subarrays.This illustrates the potential gain that both noncircularity and coprime arrays provide when considered together.The proposed algorithm has a lower computational complexity and a better DOA estimation performance than the standard estimation of signal parameters by the rotational invariance technique and Capon algorithm.Numerical simulation results illustrate the effectiveness and superiority of the proposed algorithm.

Simulation on the Models of Small Scale Passive Acoustic Sensor Arrays Based on Time-Delay Estimation Method

The passive acoustic localization with planar sensor array is introduced. Based on a method to eliminate the influence of effective sound velocity in passive detection, a new five-sensors solid array and its localization model are put forward. The factors that influence the precision of the localization are analyzed. Considering the errors from the factors synchronously, the simulation compares the solid array with the planar array. It can be proved that the five-sensor solid array is better than the four-sensor planar array in the estimation of bearing elements.

Fiber Grating-Based Strain Sensor Array for Health Monitoring of Pipelines

Pipelines are one of the most important modern energy transportation methods,used especially for the transportation of certain dangerous energy media materials such as crude oil,natural gas,and chemical raw materials.New requirements have been put forward for the health monitoring and early security warning of pipelines because of the large-scale and complicated development trend of the pipe network system.To achieve an accurate assessment of the health conditions of pipeline infrastructure,obtaining as many precise operating parameters as possible,particularly at some critical parts of the pipeline,is necessary.Therefore,a novel type of fiber grating strain sensor array is proposed herein to monitor the pipeline hoop strain.The sensor utilizes fiber grating characteristics such as light weight,corrosion resistance,remote transmission,and strong environmental adaptability.The fiber containing the grating measurement points is implanted into the composite material to complete the sensitization encapsulation and protection of the bare fiber grating.The design of the sensor array fulfills the requirements for monitoring pipeline mass data,making it easy to form a pipeline health monitoring sensor network.The sensor sensitivity is researched by using a combination of theoretical and experimental analysis.A sensitivity test,as well as linearity and stability tests,are performed on the sensor.The experimental results show that the average sensitivity of the sensor is 14.86 pm/με,and the error from the theoretical calculation analysis value is 8.75%.Due to its high reliability,good linear response and long-term stability,and the ability to reflect the exact strain change of the outer wall of the pipeline,the designed sensor can support longterm online pipeline monitoring.The fiber grating sensor array network has successfully realized the monitoring of the pipeline’s internal operation by using external strain changes.In addition to the performance benefits,there are other merits associated with the applicability of the sensor namely simple structure,compact size,manufacturing ease,and exterior installation ease.

Meso-Scale VOC-Mixture Analyzer with Tunable Separation and Microsensor Array Detection

A novel portable instrument developed for field determinations of complex mixtures of volatile organic compounds (VOCs) is described.The key features of the instrument are a miniature multi-stage adsorbent preconcentrator/focuser,two series-coupled separation columns with pressure and temperature tunable retention control,and an integrated array of four chemiresistor (CR) sensors coated with Au-thiolate monolayer-protected nanoparticles (MPN).MPN-CR array response patterns are used with retention times to identify eluting vapors.Air is used as the carrier gas.Calibrations of 20 common indoor air contaminants gave LODs in the range of 0.05 ng/g～0.53 ng/g for a 1 L sample volume.Results of preliminary analyses of characteristic VOCs generated from U.S.currency as well as vapor-phase markers of environmental tobacco smoke (ETS) at low-or sub-ng/g levels are presented.

Recognizing frequency characteristics of gas sensor array

A novel method based on independent component analyzing (ICA) in frequency domain to distinguish the frequency characteristics of multi-sensor system is presented. The conditions of this type of ICA are considered and each step of resolving the problem is discussed. For a two gas sensor array, the frequency characteristics including amplitude-frequency and phase-frequency are recognized by this method, and cross-sensitivity between them is also eliminated. From the principle of similarity, the recognition mean square error is no more than 0.085.

Micro Gas Sensor Array for Monitoring Highly Toxic Gases

Recently,the possibility of a disaster due to the improper use of highly toxic gases which are known as agents throughout the world has been increased.Therefore,the development of technology for countermeasure against CWA has been highly demanded.In this study,thick film SnO_2-based gas sensing devices were prepared and the sensing properties for the four different kinds of simulants such as dimethyl methyl phosphonate (DMMP),acetonitrile,dichloromethane and dipropylene glycol methyl ether have been investigated.And a micro sensor array consists of six devices was prepared using MEMS technology to provide high selective and reliable sensing system for the detection of chemical warfare agents.The micro gas sensor array prepared showed good sensitivity and selectivity to CWA.

Demonstration of a 4-Sensor Folded Sangac Sensor Array with Active Phase Biasing Scheme

A 4-sensor folded Sagnac sensor array with an active phase biasing scheme is presented. The overlapping of the signal and noise pulse is avoided through a time division multiplexing scheme and the noise pulses is eliminated almost completely. The scheme can address 16 sensors when the repeat frequency of input pulse is at 68.3 kHz. The alternative phase bias technique is demonstrated, which can provide sensors with stable phase bias. The future benefit of this technique is that the 1/f noise in the circuit can be suppressed.

A magnetic sensor array for spot welding quality monitor

Spot welding is affected by many factors and is difficult to monitor the nugget information with single sensor. In this paper, a new monitor system based on sensors array technique was developed for spot welding quality detection. The key part in the system is cross magnetic sensor array. It is composed of six magnetic sensors. An improved algorithm was proposed to extract the signal eigenvalue, which was based on principle component analysis. The results show that in the case of the 60 mm experiment, cross magnetic sensor array works well. And when the eigenvalues range of the cross magnetic sensor array is 0. 090 1 - 0. 098 2, the spots quality is good. The analysis of the eigenvalues of the cross magnetic sensor array allows us to determine whether the spot qualty is good or bad.

Optical sensor array for the discrimination of liquors

The discrimination of liquors plays a vital role in our daily life as a large amount of cheap alcoholic beverages and low-quality counterfeits greatly damage the health of consumers.Array-based optical sensors have been developed as a fast and effective tool to discriminate multi-analytes or complex mixtures with similar structures,such as acids,esters,aldehydes and ketones.Over the past decades,optical sensor arrays have demonstrated remarkable capabilities in fast and accurate detection of diverse types,qualities,and authentic liquors.The identification strategy mainly focuses on the specific/non-specific interactions of flavor compounds in liquors with sensor elements.The cross-reactive optical signal readouts from the combination of sensor elements with liquors and multiple machine learning algorithms are essential to ensure the discriminatory capability of sensing system.In this review,we discuss the advantages and recent advances in pattern recognition of liquors in terms of the design of various types of sensing materials and the construction strategies of sensor arrays.

Nanogenerator-based bidirectional pressure sensor array and its demonstration in underwater invasive species detection

Lakes areas,which cause catastrophic damages in both commercial fishery and ecological systems.However,current assessment strategies may pose challenges for lake-wide abundance estimation and non-target anadromous species preservation.Here,we demonstrate an efficacious species-specific non-destructive sensing system based on porous ferroelectret nanogenerator for in-situ monitoring of lamprey spawning migration using their unique suction behavior.Simulations show that the porous structure enables a redistribution of surface charges under bidirectional deformations,which allows the detection of both positive and negative pressures.The quasi-piezoelectric effect is further validated by quantitative analysis in a wide pressure range of−50 to 60 kPa,providing detailed insights into transduction working principles.For reliable lamprey detection,a 4×4-pixel sensor array is developed and integrated with a complementary metal-oxide-semiconductor(CMOS)based signal processing array thus constituting a sensing panel capable of recording oral suction patterns in an underwater environment.

Dual-Emission Carbonized Polymer Dots Combined with Metal Ions as a Single-Component Fluorescence Sensor Array for Pattern Recognition of Glycosaminoglycans

Herein,a novel dual-emission fluorescence sensor array of carbonized polymer dots(CPDs)-Cu^(2+)has been proposed,in which CPDs were prepared by one-pot hydrothermal method and Cu^(2+)acting as a quencher was combined with CPDs by electrostatic interaction.Four negatively charged glycosaminoglycans(GAGs)bearing different hydrophilic groups showed variable binding affinities towards CPDs-Cu^(2+).Upon reacting with these GAGs,the different fluorescence response signals of CPDs-Cu^(2+)can be further differentiated by principal component analysis(PCA).The CPDs-Cu^(2+)sensor array,not only allows the identification of four similarly structured GAGs,but also realizes the discrimination of different concentrations of the same GAGs and their mixtures.Remarkably,the identification of GAGs in biological fluids can also be achieved using our proposed single-component sensor array,validating its application potential.This new strategy avoids multiple sensing probes,broadens the application of tongue-mimic sensor arrays and provides a viable idea for the development of single component sensing platforms.

A pH-Regulated Colorimetric Sensor Array for Discrimination of Biothiols Based on Two Different-Sized β-Cyclodextrin-Functionalized AuNPs

The abnormal changes of biothiols are directly related to health condition of human body,and the effective identification and quantification of biothiols is of great significance for screening and diagnosis of disease.This study described the development of a p H-regulated colorimetric sensor array for discrimination of five kinds of biothiols including cysteine(Cys),glutathione(GSH),homocysteine(Hcy),cysteamine(CA)and N-acetylcysteine(NAC).The proposed sensor array was established using 5-nm-and 20-nm-sizedβ-cyclodextrin-functionalized gold nanoparticles(β-CD@Au NPs)as nonspecific receptor and signal transduction elements.Due to the different binding affinity between biothiols andβ-CD@Au NPs in various p H environments,the different aggregation behaviors of nanoparticles produced unique colorimetric response patterns,which were able to be distinguished by bare eyes and UV-vis spectrophotometer.Accordingly,principal component analysis(PCA)and hierarchical cluster analysis(HCA)were employed for pattern recognition and generated a clustering map for a clear differentiation of biothiols at the level ofμmol/L.Furthermore,it can be proved that the method was successfully applied to the analysis of biothiols in human urine samples.

Ultra-Thin Flexible Eddy Current Sensor Array for Gap Measurements

An ultra-thin flexible eddy current proximity sensor array was developed for online measurements of tiny gaps between large smooth metallic and nonmetallic surfaces of arbitrary shapes. The probe of the flexible eddy current sensor array, which includes a set of sensor coils, is fabricated on a thin flexible substrate using the flexible printed circuit board process which allows the probe to be very thin and flexible so that it can conform to the surface geometry of the measured objects. The sensor coils are connected to an inductance-capacitance oscillator, which converts the distance between the sensor coil and the metallic target to a frequency output. Experimental results show that the measurement accuracy of the sensor system can reach ±0.5% for a 2-mm gap and the sensor system is suitable for online gap measurements.

Combined Use of FSR Sensor Array and SVM Classifier for Finger Motion Recognition Based on Pressure Distribution Map

For controlling dexterous prosthetic hand with a high number of active Degrees of Freedom （DOF）, it is necessary to reliably extract control volitions of finger motions from the human body. In this study, a large variety of finger motions are discriminated based on the diversities of the pressure distribution produced by the mechanical actions of muscles on the forearm. The pressure distribution patterns corresponding to the motions were measured by sensor array which is composed of 32 Force Sensitive Resistor （FSR） sensors. In order to map the pressure patterns with different finger motions, a multiclass classifier was designed based on the Support Vector Machine （SVM） algorithm. The multi-subject experiments show that it is possible to identify as many as seventeen different finger motions, including individual finger motions and multi-finger grasping motions, with the accuracy above 99% in the in-session validation. Further, the cross-session validation demonstrates that the performance of the proposed method is robust for use if the FSR array is not reset. The results suggest that the proposed method has great application prospects for the control of multi-DOF dexterous hand prosthesis.

Construction of MoS2 field effect transistor sensor array for the detection of bladder cancer biomarkers

Bladder cancer is one of the commonest malignant tumors of urinary system with high recurrence. However, currently developed bladder cancer urine diagnosis methods are hindered by the low detection sensitivity and accuracy. Herein, a molybdenum disulfide(MoS2) nanosheets-based field effect transistor(FET) sensor array was constructed for simultaneous detection of multiple bladder cancer biomarkers in human urine. With the excellent electronic property of MoS2 and the high specific identification capability of recognition molecules, the proposed biosensor array could simultaneously detect nuclear matrix protein 22(NMP22) and cytokeratin 8(CK8) with a wide linear range of 10-6–10-1 pg mL-1 and an ultra-low detection limit of 0.027 and 0.019 aM, respectively. Furthermore, this highly sensitive and specific MoS2 FET sensor array could be used to identify bladder cancer biomarkers from human urine samples. This designed high-performance biosensor array shows great potential in the future diagnosis of bladder cancer.

Joint multiple parameters estimation for coherent chirp signals using vector sensor array

In this paper, an algorithm is proposed to estimate starting frequency （SF）, chirp rate （CR）, 2-D direction-of-arrivals （DOA） and polarization of coherent chirp signals with vector sensor arrays. The fractional Fourier transformation （FRFT） is used to estimate SF and CR of chirp signals in this method. And a new correlation matrix is reconstructed to suppress the noise. The property of the vector sensor array is employed to solve the problem of insufficient rank from signal coherence. The L-shaped uniform array of expend aperture is used to improve the precision of es- timation, and the method of solving the ambiguity of angle under the condition of coherent signals is presented. The performance of this algorithm is compared with that of spatial smoothing method to verify the efficacy of this approach.

Time/Wavelength Fiber Bragg Grating Multiplexing Sensor Array

A novel time/wavelength-multiplexed fiber Bragg grating sensor array is presented. This type of sensor array has the advantages of more points for multi-point measurement, simple structure and low cost.

PDMS/MWCNT-based tactile sensor array with coplanar electrodes for crosstalk suppression

The severe crosstalk effect is widely present in tactile sensor arrays with a sandwich structure.Here we present a novel design for a resistive tactile sensor array with a coplanar electrode layer and isolated sensing elements,which were made from polydimethylsiloxane(PDMS)doped with multiwalled carbon nanotubes(MWCNTs)for crosstalk suppression.To optimize its properties,both mechanical and electrical properties of PDMS/MWCNT-sensing materials with different PDMS/MWCNT ratios were investigated.The experimental results demonstrate that a 4 wt% of MWCNTs to PDMS is optimal for the sensing materials.In addition,the pressure-sensitive layer consists of three microstructured layers(two aspectant PDMS/MWCNT-based films and one top PDMS-based film)that are bonded together.Because of this three-layer microstructure design,our proposed tactile sensor array shows sensitivity up to−1.10 kPa^(−1),a response time of 29 ms and reliability in detecting tiny pressures.