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Recently, wearable electronics for health monitoring have been demonstrated with considerable benefits for early-stage disease detection. This article reports a flexible, bending-insensitive, bio-compatible and lightweight respiration sensor. The sensor consists of highly oriented carbon nanotube (HO-CNT) films embedded between electro-spun polyacrylonitrile (PAN) layers. By aligning carbon nanotubes between the PAN layers, the sensor exhibits a high sensitivity towards airflow (340 mV/(m/s)) and excellent flexibility and robustness. In addition, the HO-CNT sensor is insensitive to mechanical bending, making it suitable for wearable applications. We successfully demonstrated the attachment of the sensor to the human philtrum for real-time monitoring of the respiration quality. These results indicate the potential of HO-CNT flow sensor for ubiquitous personal health care applications.

A valveless microfluidic pump using a lead zirconate titanate (PZT) diaphragm actuated synthetic jet is developed and fabricated. For this present design, a valveless pump structure is developed in which the pump chamber is sealed on one side and connected to an emitting nozzle at another side. The design is simulated using the multiphysics approach and then successfully investigated with a prototype produced by a low-cost additive fabrication technique. The device's parameters, including the liquid pumping characteristics and the size of the PZT membrane, are optimized based on its desired performance. The developed device can be applied over a wide range of applications from micromixing to fluidic controlling.

Calcium phosphate (CaP) coating on melt electrowritten (MEW) substrates is a potential candidate for bone regeneration influencing the interaction of osteoblasts with implanted scaffolds. Pretreatment to improve hydrophilicity of the hydrophobic polymer fibres affects subsequent coating with bioactive compounds like CaP. Therefore, this study evaluated the subsequent stability and structural properties of CaP coated MEW Poly-ε-caprolactone (PCL) scaffolds following pre-treatment with either argon-oxygen plasma or sodium hydroxide (NaOH). Scanning electron microscopy and μ-CT showed uniform CaP coating after one hour immersion in simulated body fluid following plasma pretreatment. Moreover, fourier transform infrared spectroscopy, energy dispersive spectrometry and X-ray diffraction analysis confirmed the presence of hydroxyapatite, tetracalcium phosphate and halite structures on the coated scaffolds. Contact angle measurement showed that the plasma pretreatment and CaP coating improved the hydrophilicity of the scaffold. However, the mechanical properties of the scaffolds were degraded after both plasma and NaOH treatments. The tensile stability was significantly improved following mineralization in plasma-treated scaffolds due to the smaller crystal size formed on the surface resulting in a dense CaP layer. The results obtained by thermogravimetric analysis also confirmed higher deposition of CaP particles on coated scaffolds following plasma modification. The results of this study show that plasma pre-treated mineralized MEW PCL scaffolds are sufficiently stable to be useful for further development in bone regeneration applications. Keywords: Calcium phosphate coating, Polycaprolactone, Melt electrowriting, Apatite mineralization, Plasma treatment, Bone regeneration

In forests and membranes, Carbon nano tubes (CNT) are not individual, instead they tend to be agglomerated into bundles because of the strong van der Waals interaction. CNTs usually form into bundles containing up to hundreds or thousands of parallel CNTs named as fibres which create networks within a CNT membrane. Recently, CNT based macrostructures (yarn and membrane) have increasingly been used in various applications in electronics, medical and bioengineering. Meanwhile the volume density of CNTs impacts on mechanical and physical properties of macrostructures, the controlling of the density of membranes is very complex. Thus, in this paper, an electric processing to dilate CNT membrane is sufficiently studied and investigated by both the experiment and particle based numerical simulation. Several initially potential applications of the method are also represented not only to control the density of CNTs but also to improve the CNTs’ alignment in macro-structures.

We present a multi-physics simulation associated with experimental investigation for an electrohydrodynamic gyroscope based on ion wind corona discharge. The present device consisting of multiple point-ring electrodes generates a synthetic jet flow of ions for inertial sensing applications. Meanwhile the residual charge of jet is neutralized by an external ring electrode to guarantee the ion wind stable while circulating inside the device's channels. The working principle including the generation and then circulation of jet flow within the present device is firstly demonstrated by a numerical simulation and the feasibility and stability of the device are then successfully investigated by experimental work. Results show owing to the ion wind corona discharge based approach associated with new configuration, the present device is robust and consumes low energy.

The development of a multimodal sensing platform with multiple layers for electronic skin (e-skin) sensing of temperature and pressure has attracted considerable interest to practical applications in soft robotics, human-machine interfaces, and wearable health monitoring. In this work, we demonstrated a new platform technology with multiple sandwiched layers of highly oriented carbon nanotube membrane and polyacrylonitrile for the integration of pressure and temperature sensory functionalities into a single platform that is thin, ultra-lightweight, flexible, and wearable. The key technology of in situ deposition of sensor platform on objects or in robot interface makes this a unique method for the development of e-skins for robotic applications, offering a new approach to wearable electronics and portable health care.

A novel gyroscope using circulatory electro-hydrodynamics flow in a confined space is presented for the first time. The configuration of the new gyroscope includes three point-ring corona discharge actuators that generate ion flows in three separated sub-channels. The three ion flows then merge together when going through a nozzle of the main chamber entrance and create a jet flow. In the new configuration, the residual charge of ion wind flow is removed by a master-ring electrode located at one end of the main chamber. Under the effect of the angular speed of gyroscope, the jet flow is deflected and this deflection is sensed using hotwires. The results, which are consistently acquired by both the numerical simulation and experiment on our prototypes, demonstrate the repeatability and stability of the new approach. Since the ion wind can be generated by a minimum power, the present configuration-based device does not require any vibrating component. Thus, the device is robust, cost, and energy-effective.

A new conceptual design of electrospray has been developed to generate neutralized micro-droplet using on-chip electro-hydrodynamic. A prototype of a bipolar electrostatic atomization with chambered nozzle tips has been carried out to demonstrate the capability of spaying viable, safe, neutral and alternative droplets which can be applied in micro/nano-encapsulation, bio-scaffold production and also the polymeric micro/nanoparticle fabrication over conventional fabrication techniques as well as the direct current electro-spraying/electrospinning. Several initially experimental results as presented through this work have shown the potential application of the present device in drug delivery.

Background: The application of Photobiomodulation (PBM), Piezoelectric Surgery (PES) and Concentrated Growth Factors (CGF) in dental implant sinus lift procedure has gained popularity. Aim: To detail a two cases report on the use of PMB, PES, and CGF as a means of enhanced angiogenesis in tissue regeneration in dental implant lateral wall sinus lift procedure. Materials and Methods: This paper presents two cases report on the multi-disciplined approach using PBM, PES, and CGF as a method of enriched angiogenesis in tissue regeneration in dental implant sinus lift technique. In both patients, the sinus lateral windows were created using PES and the sinus membrane was raised to make a new partition. Surface modified dental implants (average 8 mm long) were inserted concurrently, packed with autologous fibrin-rich CGF, and then lastly induced PBM using Multiwave Locked System (MLS) laser. Radiographic and clinical evaluation was implemented to validate the efficacy of this multi-disciplined approach. Results and discussion: Postoperative revival was ordinary with no noteworthy postoperative complications. Wound closure/angiogenesis occurred shortly after day one. New bone formation in all augmented maxillary sinuses was detected alongside the implants on plain radiographs and on cone-beam computed tomograms. The patients were very happy with the overall treatment (>80%) and the success rate of implant was 100% after a usual 10 months loading period. PBM, PES, and CGF enhance angiogenesis/wound healing by speeding up wound approximation/healing, lessening the followings: postoperative pain, swelling, bleeding, speech impairment, analgesic use, and trismus. Conclusion: Using PBM, PES, and CGF as a method to enrich angiogenesis/wound healing in sinus lift rendered initial phase of satisfaction, simplicity, effectiveness, minimal complication, enhanced angiogenesis/wound healing with no cross infection and allergic reaction. Keywords photobiomodulation - piezoelectric surgery - concentrated growth factors - sinus augmentation - angiogenesis/wound healing

The paper reports the development of a particle precipitation based aerosol sampler using bipolar corona discharge ion winds with collected particles of minimized net charge. For the new approach, neutralized particles move towards a sampler under the effect of electric field and dual ion winds. Since there is no electrode or sampling chip installed inside the air-flow channel, impediments to airborne particle flow or ion winds are removed along the flow direction. In addition, the isolation of ion winds, which generate circuit, allows using various materials for the sampling chip including non-conductors and also protecting collected particles from any discharge ignition on the chip. The device mechanism is numerically simulated in OpenFOAM to study the electrofluidodynamic interaction of charged particles and bipolar ion winds. The efficiency of the new approach has been investigated by experiment with a maximum efficiency of 94%. The effects of flow rate, discharge voltage and electrode distances on the method are also evaluated.

We report a unique alternating current (AC) driven corona based air-flow generator using symmetrically arranged electrodes. Unlike the conventional configuration where one electrode generates charged ions moving towards the reference electrode, this configuration allows both negative and positive charges to simultaneously move away from the device and generate ion wind in parallel with the electrodes. In comparison with the direct current (DC) driven corona generator, the time oscillating AC field allows the device a better stabilization owing to the independence of ion wind strength from the inter-electrode spacing. Our results by both simulation and experiment showed that when the AC frequency exceeds a threshold value of 1100 Hz, the electric field at the electrode tips is determined dominantly by the charge cloud created in the previous half-cycle, resulting in stronger net electric field and thus stronger ion wind. In addition, the electrode separation in the AC driven corona based generator is less critical above the frequency threshold, yielding a more robust design with minimized susceptibility to manufacturing tolerances and impurities on the electrodes. Moreover, lower voltage levels of the AC driven system allow simpler and more economical design in the high voltage circuit of the AC generator.

This paper presents the design, fabrication, and characterization of a two-axis tilt angle sensor based on the air/liquid two-phase dielectric capacitive sensing structure. The sensor consists of f...

In this paper, we report a further study of flow-network generating four jet flows which circulate in a sealed device to experimentally investigate the feasibility and efficiency of a dual-axis gyroscope. The experiment is carried out successfully and the experimental results reasonably agreed with those obtained by numerical analysis using OpenFOAM. The flow rectifying coefficient is determined using the mathematical lump model for a vibrating system, which takes into account of the device geometry and resonant frequency. Experimental and numerical results demonstrate that the coefficient of the new system developed in this study is significantly higher than those of conventional designs. The hotwire-integrated device which can function as a dual-axis gyroscope is tested using a turntable with speeds up to 1900 rpm. The scale factor and cross-sensitivity of the system are 0.26 μV s/° and 1.2%, respectively. The cross-sensitivity and the effects of linear acceleration, actuating voltage on the diaphragm, heating power and position of hotwires are also investigated.

We report an application of ion wind in angular rate sensing. A new design of a jet flow gyroscope using ion wind corona discharge is developed by conducting a numerical simulation and then an experimental analysis with regard to the advantages of a corona-discharge-based jet flow. Ion wind is generated by applying a high–voltage between a pin, as the discharge electrode, and a ring, as the reference electrode. The current–voltage characteristics of the discharge process by experimental works is set up as the boundary condition to describe the ion wind flow in the numerical simulation. A jet flow of ion wind is observed through an experiment and a simulation. When the gyroscope is subjected to an angular rate, the induced Coriolis force deflects the ion wind. This deflection is detected using four hotwires installed downstream of the working chamber behind the reference electrode. The experimental result show that the angular rate can be detected with a sensitivity of 4.7 μV/o/s. Because ion wind can be generated with minimum power and does not require any vibrating components, the device is robust, consumes low power, and is cost-effective.

This paper develops a millimeter scale fully packaged device in which a vortex flow of high velocity is generated inside a chamber. Under the actuation by a lead zirconate titanate (PZT) diaphragm, a flow circulates with increasing velocity after each actuating circle to form a vortex in a cavity named as the vortex chamber. At each cycle, the vibration of the PZT diaphragm creates a small net air flow through a rectifying nozzle, generates a synthetic jet which propagates by a gradual circulation toward the vortex chamber and then backward the feedback chamber. The design of such device is firstly conducted by a numerical analysis whose results are considered as the base of our experimental set-up. A vortex flow generated in the votex chamber was observed by a high-speed camera. The present approach which was illustrated by both the simulation and experiment is potential in various applications related to the inertial sensing, fluidic amplifier and micro/nano particle trapping and mixing.

In this paper, we report the details and findings of a study on tri-axis convective accelerometer, which is designed with the closed-loop type heat source and thermal sensing hotwire elements. The closed-loop heat source enhances the convective flow to the central part where a hotwire is placed to measure the vertical component of acceleration. The simulation was conducted using numerical analysis, and the device was prototyped by additive manufacturing. The device, functioning as a tilt sensor and an accelerometer, was tested up to acceleration of 20 g. The experiments were successfully conducted and the experimental results agreed reasonably with those obtained by numerical analysis. The results demonstrated that the closed-loop heat source could reduce the cross effect between the acceleration components. The scale factor and cross-sensitivity had the values of 0.26 μV/g and 1.2%, respectively. The cross-sensitivity and the effects of heating power were also investigated in this study.

We present the study of a simple and efficient air-flow generator under the effect of ion winds which are created by corona discharge. Based on our recent research of ion wind with bipolar corona using parallel pins, this work reports an investigation and evaluation of the corona system in asymmetrical configurations, where the two electrodes have different tip shapes. The system of new configuration is investigated both experimentally and numerically. The numerical and experimental results are the base to establish a regime of stable operation by the measured I-V characteristics. The optimized set-up can generate an air flow up to 2.24 m/s at the atmospheric pressure. With the asymmetrical configuration of different pin tip shapes, the system can be used in many mixing applications such as mixing solvent and die where the generated vortices are also presented.

Lab on a Chip (LOC) devices minimize, integrate, automate, and parallelize laboratory functions such as mixing, separation, and incubation on a single chip. Droplet generation is one key aspect in LOC devices which allows to conduct various chemical and biochemical assays enabling biological cell studies, high throughput drug development, and diagnostic screenings. This paper presents, modelling, simulation, and experimentation of an active droplet generator that is widely used in LOC devices. The model geometry used in this study was based on a flow focusing method of droplet generation. Droplet generation from the numerical simulations was observed within flow rate ratios ranging from 0.2 to 4 using optimised droplet contraction width of the generator model. Subsequently, a prototype droplet generator was designed and developed from Polymethyl Methacrylate (PMMA) material using a layer-based fabrication method. Based on the experimental setup presented here, the calculated ratios of flow rates obtained for different voltage values have shown that the formation of droplets occur between flow rate ratios of 1.04 and 4.74. In addition, morphological parameters of the droplet images extracted from a digital image processing algorithm show that the mean diameter of the droplets decreases with decreasing flow rate ratios.

The effect of the strength of the self-induced magnetic field around a current carrying wire on thermomagnetic convection cooling in ferrofluid is experimentally and numerically investigated. Temperature-rise characteristics of the hot micro-wire for uniform Joule heating with different electric currents are compared to identify the relative importance of the strength of the axisymmetric magnetic field. Experiments are done with copper and platinum wires with current inputs adjusted to achieve the same Joule heating per unit length of wire. It was found that at high current supply (2A), mixing in ferrofluid is escalated due to thermomagnetic convection that resulted into 28% increase in average Nusselt number value which finally resulted into temperature drop of 8 K in comparison to DIW. Comparison of results for different self-induced magnetic field strengths in ferrofluid and deionized water clearly show that the observed cooling phenomenon is due to the self-induced magnetic field interacting with the magnetic fluid rather than natural-convection or other nanofluid-related mechanisms. For 1.83 W J heating, the temperature of the copper wire is 6 K lower than that of the platinum wire. Temperature and velocity contours obtained from simulations based on a 2-D single-phase model including a temperature-dependent magnetic body force provide flow visualization and further confirmed that the thermomagnetic cooling is responsible for the observed behaviour.

We present a simple and efficient airflow generator utilizing the effect of ion wind by generating simultaneously both the positive and negative ions from two sharp electrodes mounted parallel to each other. The unique bipolar geometrical setup eliminates the effect of space charge by the high recombination rate of oppositely charged ions. The two-electrode arrangement is symmetrical, where the electrode creating charged ions of one polarity also serves as the reference electrode to establish the electric field required for ion creation by the opposite electrode, and vice versa. Unlike the conventional setup, with a single electrode generating ion wind with movement toward the reference electrode, in this configuration the air movement is parallel to the electrodes, and is directed away from the device. The airflow behavior is studied by both experiments and numerical simulation. The ion wind speed has a linear relationship with the square root of the discharge current, U ∝ √I, and its measured values agree well with simulation. The characterization of the discharge current-voltage relationship was derived from mathematical processing in the general form I = b(V - V o ) n . The ion wind speed and the current-voltage characteristics depend on the interspace between the electrodes and the electrode geometry. An ion wind speed on the order of ms -1 is created with a microampere discharge current, resulting in a total net charge of only several femtoampere. The proposed configuration is beneficial in minimizing the power consumption of the system, and in enabling air recirculation for airflow control applications, cooling applications, propulsion technology, and micropump design, especially for the applications where neutralized ion wind flow is required.

A novel air-flow generator based on the effect of ion wind has been developed by the simultaneous generation of both positive and negative ions using two electrodes of opposite polarity placed in parallel. Unlike the conventional unipolar-generators, this bipolar configuration creates an ion wind, which moves away from both electrodes and yields a very low net charge on the device. The electro-hydrodynamic behavior of air-flow has been experimentally and numerically studied. The velocity of ion wind reaches values up to 1.25 m/s using low discharge current 5 μA with the kinetic conversion efficiency of 0.65% and the released net charge of −30 fA, 8 orders of magnitude smaller compared with the discharge current. Due to easy scalability and low net charge, the present configuration is beneficial to applications with space constraints and/or where neutralized discharge process is required, such as inertial fluidic units, circulatory flow heat transfer, electrospun polymer nanofiber to overcome the intrinsically instability of the process, or the formation of low charged aerosol.

A fully packaged convective vortex gyrometer actuated by a PZT diaphragm is reported. The flow circulates at higher velocity after each actuating circle to form a vortex in the desired chamber. The vortex is characterized by hotwire anemometry. The device is initially designed based on a numerical analysis whose results are used to set up the experiment. The angular rate sensing of the device is successfully tested using a turntable. The technique is a potential solution to various applications related to inertial sensing and fluidic amplifier.

In this paper, a PZT synthetic jet that can function as both an efficient pumping and mixing device is developed. Compare with the conventional design where the practice of controlling the internal flow is undertaken by microvalves structure, this approach promotes the durability and allows the device to work with different liquids at high Reynold number without losing of backflow from the diffuser, therefore provides efficient mixing. The pumping performance is applicable for commercialized counterparts while the homogeneous medium was obtained at downstream in the experiments, which was further confirmed by simulation. Notably, the chaotic mixing feature of the device is also applicable for immiscible liquids with the micro-droplet formation result at the outlet.

The development of electronic skin (e-skin) and soft tactile sensing has recently attracted great interest. Here we report for the first time on a novel ionic liquid (IL) based soft pressure sensor with multi-point touch detection capability using 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]+[BF4]−) as a highly conductive sensing medium. The sensing mechanism is attributed to the repopulation of charge cations and anions in aqueous solution under pressure. The sensor can detect two dimensional touching positions with a sensitivity of −0.28% kPa−1. Our sensor showed good stability and temperature independence thanks to the incompressibility of IL in the range of touch pressure and the appropriate signal measurement configuration. We successfully demonstrated the sensor's capability to detect multi-point human touch with different pressure levels. Our simple design with smart structures and ease of fabrication processes enable the development of a soft and low-cost sensor with multiple-point sensing capabilities on a single chip.

Carbon nanotubes (CNTs) are of high interest for sensing applications, owing to their superior mechanical strength, high Young’s modulus and low density. In this work, we report on a facile approach for the fabrication of carbon nanotube devices using a four terminal configuration. Oriented carbon nanotube films were pulled out from a CNT forest wafer and then twisted into a yarn. Both the CNT film and yarn were arranged on elastomer membranes/diaphragms which were arranged on a laser cut acrylic frame to form pressure sensors. The sensors were calibrated using a precisely controlled pressure system, showing a large change of the output voltage of approximately 50 mV at a constant supply current of 100 µA and under a low applied pressure of 15 mbar. The results indicate the high potential of using CNT films and yarns for pressure sensing applications.

In this paper, we present a study on a jet flow, assisted by low net charge ion wind from bipolar corona discharge setup. The ion wind is simultaneously generated from both positive and negative electrodes placed in parallel, adding momentum to the bulk flow directed alongside the electrodes and focused in the middle of interelectrode space. The electrodes are connected to a single battery-operated power source in a symmetrical arrangement, where the electrode creating charged ions of one polarity also serves as the reference electrode to establish the electric field required for ion creation by the opposite electrode, and vice versa. Multiphysics numerical simulation is carried out with programmable open source OpenFOAM, where the measured current-voltage is applied as a boundary condition to simulate the electrohydrodynamics flow. The jet flow inside the device is verified by hotwire anemometry using hotwires embedded within the device, with the measured values in good agreement with simulation. The corona discharge helped to focus the jet and increased the flow peak velocity from 1.41 m/s to 2.42 m/s with only 27.1 mW of consumed discharge power. The device is robust, ready-to-use and minimal in cost. In addition, as the oppositely charged corona flows are self-neutralized, the generated air flow remains neutral and therefore does not attach to a particular target, which expands the application range. These are important features, which can contribute to the development of multi-axis fluidic inertial sensors, fluidic amplifiers, micro blowers, gas mixing, coupling and analysis with space constraints and/or where neutralized discharge process is required, such as circulatory flow heat transfer or the formation of low charged aerosol for inhalation and charged particle deposition.

Recent advances in assembling Carbon NanoTubes (CNTs) into macrostructures with outstanding properties, such as high tensile strength, high conductivity and porosity, and strong corrosive resistance, have underpinned potentially novel applications. For example, in advanced electronics, bioengineering and nanomechanics. This paper focuses on the development of (i) the piezoresistive polydimethylsiloxane–CNT (PDMS–CNT) composite membrane, and (ii) the thermo-resistive CNT hotwire using a technique of producing highly aligned CNT yarns and films. Our experimental results show that while PDMS–CNT films possess an outperformed gauge factor (10.7) compared with ones of CNT films in recent publications and several metals, a clear linear relationship of the resistance versus the temperature for a hotwire using CNT yarn is observed. Hence, the work supplies valuable evidence in the use of CNT films and yarns in several potential applications as thermal sensing elements and anemometric hotwires, respectively.

Harvesting sustainable energy resources from surrounding environments to power small electronic devices and systems has attracted massive research attention. Herein, we develop a novel technology to harvest light energy to self-power and simultaneously sense mechanical acceleration in a monolithic structure. When the photonic gate is illuminated the operation mode of the device changes from conventional mode to light harvesting and self-powered operation. The light illumination provides a gradient of majority carrier concentration on the top semiconductor layer, generating a lateral photovoltage, which is the output voltage of the sensor. Under acceleration, the mechanical inertial force induces stress in the sensor material leading to the change of mobility of the charge carriers, which shifts their diffusion rate, and hence changes the gradient of the majority carriers and the lateral photovoltage. The sensitivity at 480 lx light illumination was measured to be 107 μ V / g , while it was approximately 30 μ V / g under the ambient light illumination without any electrical power source. In addition, the acceleration sensitivity is tunable by controlling parameters of the photonic gate such as light power, light spot position and light wavelength. The integration of sensing and powering functions into a monolithic platform proposed in this work eliminates the requirement of external power sources and offers potential solutions for wireless, independent, remote, and battery-free sensing devices and systems.

In this research, a novel Automated Fluid Management System (AFMS) was designed, analysed and fabricated for endoscopy aided gynaecological surgeries in order to prevent complications arise due to fluid overload. The proposed system consists of a peristaltic pump, suction mechanism and fluid measurement system integrated with a graphical user interface which can also control and monitor through a wireless network system. The device serves functionalities such as regulating saline flow rate, limiting saline suction rate, setting saline absorption limits for different patients and indicating real-time fluid deficit. This paper discusses designing of a non-contact pump for gynaecological surgeries, development of the control system for AFMS and the comparison of experimental results of the fabricated non-contact pump with theoretical pump characteristics.

Stretchable and wearable sensor technology has attracted significant interests and created high technological impact on portable healthcare and smart human-machine interfaces. Wearable electromechanical systems are an important part of this technology that has recently witnessed tremendous progress toward high-performance devices for commercialization. Over the past few years, great attention has been paid to simultaneously enhance the sensitivity and stretchability of the electromechanical sensors toward high sensitivity, ultra-stretchability, low power consumption or self-power functionalities, miniaturisation as well as simplicity in design and fabrication. This work presents state-of-the-art advanced materials and rational designs of electromechanical sensors for wearable applications. Advances in various sensing concepts and structural designs for intrinsic stretchable conductive materials as well as advanced rational platforms are discussed. In addition, the practical applications and challenges in the development of stretchable electromechanical sensors are briefly mentioned and highlighted.

Silicon carbide (SiC)‐based microsystems are promising alternatives for silicon‐based counterparts in a wide range of applications aiming at conditions of high temperature, high corrosion, and extreme vibration/shock. However, its high resistance to chemical substances makes the fabrication of SiC particularly challenging and less cost‐effective. To date, most SiC micromachining processes require time‐consuming and high‐cost SiC dry‐etching steps followed by metal wet etching, which slows down the prototyping and characterization process of SiC devices. This work presents a lithography and etching‐free microfabrication for 3C‐SiC on insulator‐based microelectromechanical systems (MEMS) devices. In particular, a direct laser ablation technique to replace the conventional lithography and etching processes to form functional SiC devices from 3C‐SiC‐on‐glass wafers is used. Utilizing a single line‐cutting mode, both metal contact shapes and SiC microstructures can be patterned simultaneously with a remarkably fast speed of over 20 cm s−1. As a proof of concept, several SiC microdevices, including temperature sensors, strain sensors, and microheaters, are demonstrated, showing the potential of the proposed technique for rapid and reliable prototyping of SiC‐based MEMS.

In this Letter, we present an electrohydrodynamic atomization (EHDA) technology that generates and delivers charge reduced nanoparticles to open space without a collector electrode. The backward ring-nozzle ac EHDA system driven at sub-kHz frequencies generates alternatively charged particles, which exert electric force and recombine in the vicinity of the spraying electrode. This unique configuration creates a stable jet stream of charge reduced nanoparticles, contrary to classical dc EHDA systems. Experiments indicate that nanoparticles are emitted through a wide range of voltages and frequencies, matching up to the hydrodynamic time of the cone jet model. These unique advantages of the new system would empower the nanoparticle EHDA devices for aerosol drug delivery in bio and health care applications.

This paper presents the design and simulation of MEMS based piezoresistive pressure sensor for microfluidic applications. Geometrical parameters are very much considerable when designing microstructure of the pressure sensor. Hence, an analysis is carried out by changing the dimensional parameters of three different diaphragm geometries namely square shaped diaphragm, circular shaped diaphragm and cross sectional beam shaped diaphragm respectively. This is performed in three dimensional mesh plots using Matlab. The Finite Element Method (FEM) analyses are performed in COMSOL and by comparing the results, the square type diaphragm is chosen as best diaphragm geometry for the microfluidic applications. In addition, modal analysis is carried out by using Ansys to identify the natural frequency of the best diaphragm geometry. Also Piezoresistive sensing elements are designed and simulated by performing coupled field analysis using COMSOL Multiphysics. Simulation results reveal that piezo resistive square type pressure sensors have high sensitivity in a wide range of pressures.

A new design of a jet flow gyroscope is developed by employing the advantages of a corona-discharge-based jet flow. Ion wind is generated by applying a high-voltage between a pin, as the discharge electrode, and a ring, as the reference electrode. When the gyroscope is subjected to an angular rate, the induced Coriolis force deflects the ion wind. This deflection is detected using four hotwires installed downstream of the working chamber behind the reference electrode. Both the experimental and numerical study have been conducted to study the phenomenon. The results show that the angular rate can be detected with a sensitivity of above $15 \mu \text{V}/{}^{\circ}/\text{s}$. Because ion wind can be generated with minimum power and does not require any vibrating components, the device is robust, consumes low power, and cost-effective.

This paper reports for the first time a millimeter scale fully packaged device which generates a vortex flow of high velocity. The flow which is simply actuated by a PZT diaphragm circulates with a higher velocity after each actuating circle to form a vortex in a desired chamber. The design of such device is firstly conducted by a numerical analysis using OpenFOAM. Several numerical results are considered as the base of our experiment where a flow vortex is observed by a high speed camera. The present device is potential in various applications related to the inertial sensing, fluidic amplifier and micro/nano particle trapping and mixing.

In this paper, an efficient electrostatic particle sampling system is developed based on the neutralized ion wind. Compare with the conventional schemes where unipolar ion is used to charge the airborne sample and the sampling stage is fixed as a part of high voltage circuit, the new approach allows sampling stage to be electrically floated and adds insignificant charge to the bioaerosol, thus reduces damages to the microorganisms while provides design flexibility and good collecting efficiency. The approach is suitable for the combination with a microfluidic interface to develop complex aerosol-to-hydrosol bio-samplers.

Flexible multifunctional electronic devices are of high interest for a wide range of applications including thermal therapy and respiratory devices in medical treatment, safety equipment, and structural health monitoring systems. This paper reports a scalable and efficient strategy of manufacturing a polyacrylonitrile-carbon nanotube-polyacrylonitrile (PAN-CNT-PAN)robust flexible platform for multifunctional electronic devices including flexible heaters, temperature sensors, and flexible thermal flow sensors. The key advantages of this platform include low cost, porosity, mechanical robustness, and electrical stability under mechanical bending, enabling the development of fast-response flexible heaters with a response time of ≈1.5 s and relaxation time of ≈1.7 s. The temperature-sensing functionality is also investigated with a range of temperature coefficient of resistances from −650 to −900 ppm K−1. A flexible hot-film sensing concept is successfully demonstrated using PAN-CNT-PAN with a high sensitivity of 340 mV (m s−1)−1. The sensitivity enhancement of 50% W−1 is also observed with increasing supply power. The low cost, porosity, versatile, and robust properties of the proposed platform will enable the development of multifunctional electronic devices for numerous applications such as flexible thermal management, temperature stabilization in industrial processing, temperature sensing, and flexible/wearable devices for human healthcare applications.

This paper presents a study on a jet flow assisted by low net charge ion wind generated from bipolar corona setup, adding momentum to the bulk flow directed alongside the electrodes and focused in the middle of interelectrode space. It was confirmed that with only 27.1 mW of consumed discharge power, the corona helped to focus and increased the flow peak velocity up to 71.6%, i.e., from 1.41 m/s to 2.42 m/s. Because the generated air flow remains neutral, this work can contribute to the development of multi-axis fluidic inertial sensors, fluidic mixing and analysis with space constraints and/or where neutralized discharge process is required.

A valveless microfluidic pump fabricated by additive fabrication technology is presented. Nozzle/diffuser structures are used to direct the flow of liquid currents inside the PZT-based micropump. A unique design using the collision of two inlet currents helps reduce the back-flow during the suction phase and promotes mixing ability. The micropump is simulated and a positive flow rate is observed at the outlet. The performance of the pump is further investigated at different driving frequencies and voltages. Simulation study on the nozzle/diffuser helps determine an efficient configuration of the nozzle/diffuser of 6° opening angle. The proposed micropump is suitable for low-cost disposable applications and is capable of delivering a controlled amount of liquid.

This paper reports on the design and simulation of a novel MEMS based convective gyroscope which can independently detect three components of angular rate. The sensor was designed with standard bulk MEMS technology. The 3D jet flow was simulated in the confined space formed by MEMS compatible laminated-structures. The configuration of the sensor consists of a PZT diaphragm, caps, in-plane tungsten hotwires located on the surface of a 0.4mm-thick circular silicon frame with diameter of 10mm. The simulated scale factors of the sensor are SFz = 0.83 μV/o/s, SFx = SFy = 3.10 μV/o/s. In measurement application, the 3DOF gyro eliminates the sensor-to-sensor misalignment, and therefore provides accurate measurement with small cross-sensitivity. The sensor also has high shock resistance since no proof mass is used.

This paper describes the design, simulation, and fabrication of a dual-axis gyroscope, whose working principle is based on the thermal convective and thermoresistive effects in lightly doped p-type silicon. The sensor configuration consists of a piezoelectric pump and a microthermal sensing element that is packaged in an aluminum case with a diameter of 14 mm and a length of 25 mm. The novel structure of the sensing element reduces the thermal-induced stress up to 89% as compared with the previous design. The sensor has been fabricated by micro- electromechanical systems technology, and completely packaged and characterized. The measured sensitivities of the gyroscope for the X-axis and Y-axis were 0.082 and 0.078 mV/deg/s, respectively. The cross sensitivities between the two input axes were less than 0.26%, and the nonlinearity was smaller than 0.5% full scale in the range of plusmn200deg/s. The resolution was 0.2deg/s at a measurement frequency of 1 Hz. The noise equivalent rate was 0.18deg/s/radicHz, which is equivalent to an angle random walk of 10.8deg/radich in a 65-Hz bandwidth. The offset drift was 360deg/h in 12-h measurement.

In this paper, we present the optimization of the PZT diaphragm pump for application in gas gyroscope. A circular flow inside the sealed case is simulated in detail by utilizing 3D compressible flow with the interaction of fluid-solid phase and the transient analysis is employed. The working principle and the effect of the jet-pump integrated inside the sensor are explained and validated by experiments using anemometry technique. The results verified that configuration of the pump is optimized and the peak velocity of the flow at the sensing element is 3.5m/sec after starting the pump 3.6ms. A novel structure of the sensing element of the gas gyroscope, consists of thermistor and heater, is also reported. The thermistor is heated by a separate heater, whose power is supplied independently form that of thermistor. This design allows low voltage on the thermistor, therefore the noise is reduced. Both heater and thermistor are optimized in order to reduce the thermal induced stress which occurred in the old thermistors at working temperatures. The thermal stress appeared in p-type silicon thermistors reduced the performance of sensor by 7.5%, which is calculated and experimentally confirmed.

This paper presents the development of a dual axis convective microaccelerometer, whose working principle is based on the convective heat transfer and thermo-resistive effect of lightly-doped silicon. Different with developed convective accelerometer, the sensor utilizes a novel structure of the sensing element which can reduce 93% of thermal-induced stress. Moreover, the thermistors are made from low-doped p-type silicon, which has the TCR higher than that of metals and poly-silicon convective accelerometer. By using numerical method, the chip dimensions and the package size are optimized. The sensitivity of the sensor was simulated; other characteristics such as frequency response, shock resistance, noise problem are also deeply investigated. The sensor has been fabricated by MEMS process and characterized by experiments.