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It is critical to investigate the charge carrier gradient generation in semiconductor junctions with an asymmetric configuration, which can open a new platform for developing lateral photovoltaic and self-powered devices. This paper reports the generation of a charge carrier gradient in a 3C-SiC/Si heterojunction with an asymmetric electrode configuration. 3C-SiC/Si heterojunction devices with different electrode widths were illuminated by laser beams (wavelengths of 405, 521, and 637 nm) and a halogen bulb. The charge carrier distribution along the heterojunction was investigated by measuring the lateral photovoltage generated when the laser spot scans across the 3C-SiC surface between the two electrodes. The highest lateral photovoltage generated is 130.58 mV, measured in the device with an electrode width ratio of 5 and under 637 nm wavelength and 1000 μW illumination. Interestingly, the lateral photovoltage was generated even under uniform illumination at zero bias, which is unusual for the lateral photovoltage, as it can only be generated when unevenly distributed photogenerated charge carriers exist. In addition, the working mechanism and uncovered behavior of the lateral photovoltaic effect are explained based on the generation and separation of electron-hole pairs under light illumination and charge carrier diffusion theory. The finding further elaborates the underlying physics of the lateral photovoltaic effect in nano-heterojunctions and explores its potential in developing optoelectronic sensors.

Giant piezoresistive effect enables the development of ultrasensitive sensing devices to address the increasing demands from hi-tech applications such as space exploration and self-driving cars. The discovery of the giant piezoresistive effect by optoelectronic coupling leads to a new strategy for enhancing the sensitivity of mechanical sensors, particularly with light from light-emitting diodes (LEDs). This paper reports on the piezoresistive effect in a 3C-SiC/Si heterostructure with a bonded LED that can reach a gauge factor (GF) as high as 18 000. This value represents an approximately 1000 times improvement compared to the configuration without a bonded LED. This GF is one of the highest GFs reported to date for the piezoresistive effect in semiconductors. The generation of carrier concentration gradient in the top thin 3C-SiC film under illumination from the LED coupling with the tuning current contributes to the modulation of the piezoresistive effect in a 3C-SiC/Si heterojunction. In addition, the feasibility of using different types of LEDs as the tools for modulating the piezoresistive effect is investigated by evaluating lateral photovoltage and photocurrent under LED's illumination. The generated lateral photovoltage and photocurrent are as high as 14 mV and 47.2 μA, respectively. Recent technologies for direct bonding of micro-LEDs on a Si-based device and the discovery reported here may have a significant impact on mechanical sensors.

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.

The study presents the design and fabrication process of a novel microfluidic active droplet generator and development of a controller to actuate the integrated micropumps. The proposed active droplet generator consists of a droplet generation geometry and two microfluidic pumps to control the flow rate of the continuous phase fluid and the dispersed phase fluid to generate a microflow towards the droplet generation geometry. The droplet generator is developed based on flow-focusing geometry. Proposed micropumps have a pump chamber and a reservoir. A layer by layer method is adapted in fabricating the active droplet generator in which Polymethyl Methacrylate (PMMA) is used as the material. A heat treating based bonding method is discussed in combining fabricated PMMA layers together. Piezoelectric transducer, which is used as the actuator, is made of Lead Zirconate Titanate (PZT) and integrated into the micropump geometry to produce the microflow. The developed controller is capable of providing a range of shapes, frequencies, and amplitudes for the input signal leading to successful operations of the active droplet generator.

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 strain sensor with high flexibility using ionic liquid is proposed for sensing movements of human body. The resistance strain sensor is constructed from a silicon tube filled fully with a mixture of aqueous sodium chloride and glycerin sealed gold-coated electrodes. When an external force is applied to the sensor, the silicon tube deforms resulting in a change in the sensor resistance value. The proposed sensor was fabricated and experimentally characterized under several working conditions. Good performance was demonstrated in detecting the movement of human leg and fingers. The proposed simple sensor has high potential in wearable applications.

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

We report for the first time a lightweight, flexible and wearable hot-film flow sensor for real-time monitoring of human respiration. The sensor was manufactured by spinning and electrospinning methods from spinnable carbon nanotube (CNT) forest grown on silicon wafers and polyacrylonitrile (PAN). The sensor exhibited high sensitivity of 340 mV/(m/s), excellent flexibility, wearability and stability under bending and other mechanical disturbances. We successfully demonstrated a CNT wearable patch affixed to human upper lip for real-time monitoring of human respiration. The results indicate that our sensor can be employed to monitor sleep quality, personal health care and other clinical evaluations.

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...

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.

E-skin with physical sensing capability has attracted considerable interest towards practical applications in soft robotics, human–machine interfaces, and wearable health monitoring. However, the development of a multimodal sensing platform with multiple layers for e-skin sensing of temperature and pressure has faced challenges due to the typical use of bare or single sensing layers as well as the complication of integration of multifunctional sensing modules onto curved surfaces. Herein, we demonstrate a new platform technology with multiple sandwiched layers of highly oriented carbon nanotube (CNT) films and polyacrylonitrile (PAN) for 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.

This paper applies our recent approach to generate a circulatory jet flow within a confined space using ionic wind by the corona discharge. A millimetre-scaled prototype with bipolar discharge configuration, which consists of two pin electrodes, nozzle, working chamber, two circulating channels and three hotwires, was designed, manufactured and investigated. A dielectric barrier of 1.0 mm thickness, installed between the parallel electrodes of opposite polarity, is utilized in order to possibly minimize the inter-electrode distance, provide a smooth current-voltage discharge characteristic and prevent electrical spark. The experimental results demonstrate that the jet flow circulates inside the device with a average velocity of 0.7 m/s. The characteristics of flow by experiment are in reasonable agreement with the numerical analysis using the finite-volume method. The device specifications were investigated with several parameters including the discharge voltage on the electrode and the heating power on hotwires. In addition, the dependence of packaging conditions on the discharge process and the effect of alternating current on the generation of ion wind are also presented. The device has low power consumption of 33 mW, and great versatility for applications in fluidic inertial sensors, fluidic amplifiers or gas mixing.

In this paper, we improve and develop a micro cam system, in which reciprocating linear movement of two electrostatic linear comb-drive actuators (ELCA) is transformed into the unilateral rotation of a cam rim through six elastic wings of motion-transmission mechanisms. The system was fabricated by using SOI-MEMS technology and only one photo mask. Our experimental results show that the new micro cam system runs stably while the driving frequency ranging from 1 to 30 Hz with the driving voltage V pp = 100 V. In addition, the average angular velocities of the cam rim matched with the theoretical results better than the velocities measured in the previous micro cam system.

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.

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.

Design and implementation of sensing devices have been driven by the need for high sensitivity, low cost, and simple fabrication. Ionic liquids have some desirable properties for soft sensor design in terms of their volatility and conductivity. By applying low cost and simple fabrication methods, we present a multifunctional pressure and temperature sensor. Preliminary results show a sensitivity of 0.24 × 10−3 kPa−1 and −17,000 ppm/K for pressure and temperature respectively. Showing high promise for the presented ionic liquid in soft sensor design. Further investigation into the measuring method, structure, and working principle of the materials involved could provide a higher quality multimodal and multifunctional device.

In this paper, we report on a miniaturized device that can generate ion wind flow with very low net charge. Both positive and negative ions are simultaneously generated from two sharp electrodes placed in parallel, connected to a single battery-operated power source. 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. The numerical simulation is carried out with programmable open source OpenFOAM, where the measured current-voltage is applied as boundary condition to simulate the electrohydrodynamics flow. The air flow inside the device is verified by eight hotwires embedded alongside the downstream channel. It was confirmed that the jet flow generated in the channel has a linear relationship with the square root of the discharge current and its measured values agree well with simulation. The device is robust, ready-to-use and minimal in cost. These are important features that can contribute to the development of multi-axis fluidic inertial sensors, fluidic amplifiers, gas mixing, coupling and analysis. The proposed configuration is beneficial 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 intrinsic instability of the process, or the formation of low charged aerosol for inhalation and deposition of charge particles.

In this paper, we report on a miniaturized device that can generate multiple jet flows circulated in a confined system. The device has a flow network comprised of four symmetrical working chambers connected with a pump chamber. The pump chamber is actuated by a PZT diaphragm. The flows in the device are studied by a computational fluid dynamics simulation and experimental measurements. The numerical simulation is carried out with programmable open source OpenFOAM, where the vibration of the PZT diaphragm is modeled with a newly developed boundary condition. Flow inside the device is verified by two hotwires embedded in each working chamber. It was confirmed that the flows generated in the four sensing chambers were almost identical. The performance of the device can be customized either by fluidic parameters, such as the driving voltage on the diaphragm, or by heat transfer processes, such as heating current of the hotwire or by alternating the gas media. The device is robust, ready-to-use and minimal in size. These are important features that can contribute to the development of multi-axis fluidic inertial sensors, fluidic amplifiers, gas mixing, coupling and analysis.

We present a pressure sensing unit based on a unique corona discharge setup using symmetrical electrode arrangement with simultaneous positive and negative corona generation. The device generates stable corona discharge and enables reliable air pressure measurement in the range of 80–105 kPa, tested with five prototypes. The current–voltage characteristics of bipolar discharge system is analyzed in general form and three governing parameters, namely electrode geometry, electrode distance and discharge current, are studied in relation with absolute pressure. The sensors are driven with constant discharge current as low as 1 μA. The measured sensitivity is in good agreement with theoretical prediction and the sensor stability has been confirmed with 20-h continuous test without sensitivity deterioration. The sensitivity does not depend on the tested temperature range and its variation between devices is small, approximately ±3.0%. The advantage of the proposed system compared with similar corona-based constructions is its stable operation at low current with low power consumption and minimum electrode deterioration, which provides a cost effective and reliable solution.

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.

A flexible pressure sensor with a rudimentary, ultra-low cost, and solvent-free fabrication process is presented in this paper. The sensor has a graphite-on-paper stacked paper structure, which deforms and restores its shape when pressure is applied and released, showing an exceptionally fast response and relaxation time of &asymp, 0.4 ms with a sensitivity of &minus, 5%/Pa. Repeatability of the sensor over 1000 cycles indicates an excellent long-term stability. The sensor demonstrated fast and reliable human touch interface, and successfully integrated into a robot gripper to detect grasping forces, showing high promise for use in robotics, human interface, and touch devices.

In this paper, we report the design study of a fluidic device that produces four microjet flows comprising two perpendicular pairs of flow and the application of these jets for an angular rate sensor. The jets were created in a closed fluidic network without a check valve and they can freely deflect in a confined sensing chamber. The formation of the continuous flow in a confined space has been confirmed by experiment. This allows the study to a triple-axis angular rate sensor whose working principle relies on the deflection of a jet in a rotating frame. In this paper, the formation of the jets is considered such that the jets have an axisymmetric property, which is key to overcoming the apparent decoupling and cross sensitivity. The triple-axis angular rate sensor can be designed with only four thermal sensing elements. The transient flow simulation under an applied angular velocity provides a design with small size and minimum number of hotwires, which is beneficial for single-chip development and also maintains compatibility with bulk microfabrication technology. While the sensing performances of the three axes are in the same order of magnitude, the cross sensitivity is two orders smaller than that in the published results. In addition to the inertial sensing application, this paper can be adapted to help researchers quickly develop a prototype or to integrate an inertial sensing component in their own microfluidic, microbio, or lab-on-a-chip systems.

This paper presents a novel anemometry based on bipolar corona discharge probe with symmetrically arranged parallel electrodes, which is potentially applicable for in-situ measurement. With the proposed configuration, under the existence of the airflow, the decomposed gas is redistributed towards the downstream electrode, and changes the current-voltage characteristics of the system. Experimental study on the anemometry characteristics demonstrates the possibility of measuring a wide range of air flow rate/ flow velocity, i.e., up to 80 l/m.

This paper reports a novel device for generating circulatory jet flow using bipolar discharge configuration. This arrangement, in which two electrodes serve as mutual emitters and reference defining the electric field, allows to generate simultaneously ionic wind with opposite charge, thus the ion flow is self-neutralized while keeping the momentum in desired direction. In order to prevent system from sparking over, between the two parallel electrodes is installed one millimetre thick polypropylene wall. Experiment and simulation has shown that the air flow is successfully circulated in the confined device with peak velocity of 2 m/s while consuming only 33 mW.

In this paper, we present a coplanar differential capacitively coupled contactless conductivity detection (CD-C4D) structure for the detection of tiny objects with dimension in micro scale. The differential capacitance changed due to the occurrence of an object in micro scale in is detected and used to recognize the presence as well as properties (i.e., electrical property and moving speed) of the object in fluidic flow. The experimental results and discussion in this paper can be generalized to any living cell or particle detection applications.

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.

We have developed and characterized a planar fluidic device consisting of a piezoelectric (PZT) acutated valveless micropump and a p-type silicon hotwire as a flow sensor. The device is fabricated by standard MEMS process. The performance of the device is studied by experiment and simulation. The flow rate and backpressure attain 2.9 mL/min and 0.3 kPa, respectively, when using a 50 Vp–p sinusoidal driving voltage at the resonant frequency of 7.9 kHz. At low driving voltage of 10 Vp–p where the pump performance cannot be resolved by conventional flow meter, a flow rate of 0.05 mL/min is obtained by the hotwire. The successful integration of hotwire allows the device to be applicable to lab-on-a-chip analysis, gas sensing, and other systems where the integration and precise flow are required.

A gas-jet micro pump with novel cross-junction channel has been designed and fabricated using a Si micromachining process. The valveless micro pump is composed of a piezoelectric lead zirconate titanate (PZT) diaphragm actuator and fluidic network. The design of the valveless pump focuses on a cross-junction formed by the neck of the pump chamber and one outlet and two opposite inlet channels. The structure of cross-junction allows differences in fluidic resistance and fluidic momentum inside the channels during each PZT diaphragm vibration cycle, which leads to the gas flow being rectified without valves. The flow channels were easily fabricated by using silicon etching process. To investigate the effects of the structure of the cross-junction on the gas flow rate, two types of pump with different cross-junction were studied. The design and simulation were done using ANSYS-Fluent software. The simulations and experimental data revealed that the step-nozzle structure is much more advantageous than the planar structure. A flow rate of 5.2 ml/min was obtained for the pump with step structure when the pump was driven at its resonant frequency of 7.9 kHz by a sinusoidal voltage of 50 Vp–p.

A piezoelectric-driven valveless micro jet pump with a novel channel structure has been designed and fabricated. The simple structure micro jet pump consists of a lead zirconate titanate (PZT) diaphragm and flow channels. The design of the flow channels focuses on a cross junction formed by the neck of the pump chamber and one outlet and two opposite inlet channels. This structure allows differences in fluidic resistance and fluidic momentum inside the channels during each pump vibration cycle. To confirm the pump operation, a prototype was fabricated using polymethyl methacrylate as a base plate and a conventional machining technique. Two types of pump with nozzle depths of 0.5 and 0.2 mm were prepared, and the depth effect on the flow rate was investigated. The pump chamber has an 11.8 mm diameter, a 0.5 mm depth, and a volume of 0.055 cm3. The maximum flow rate of 17 ml/min at 400 Pa was obtained when the pump was driven at a resonant frequency of approximately 6 kHz by a sinusoidal voltage of 30 Vp–p.

In this paper, we present the simulation and fabrication of the gas gyroscope. The gas flow inside the hermetically packed sensor is simulated by utilizing 3-D transient compressible flow analysis. The pump working principle and the effect of the Coriolis acceleration on the laminar jet are validated by both analytical formulas and experiments. The sensor utilizes a new sensing element consisting of a thermistor heated by an interior heater, which is independently power-supplied. The sensor performance can be adjusted by the applied voltage on the heater. Both heater and thermistor are optimized in terms of thermal stress. The effect of thermal stress in a p-type silicon thermistor reduces the performance of sensor by 9.5%. The sensor has been calibrated and the role of the heater is verified.

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 presents the development of a dual-axis convective microaccelerometer, whose working principle is based on the convective heat transfer and thermoresistive effect of lightly doped silicon. In contrast to the developed convective accelerometer, the sensor utilizes new structures of the sensing element which can reduce at least 90% of the thermally induced stress. By using a numerical method, the dimensions of the sensing chip and of the package are optimized. The sensitivity of the sensor is simulated; other characteristics such as frequency response, shock resistance and the noise problem were investigated. The sensor has been fabricated by a microelectrical mechanical systems (MEMS) process and characterized by experiments.

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.

In this paper, we report on the design, simulation and experimental validation of a miniaturized device that can generate multiple jet flows circulated in a confined system. The device has a flow network comprised of four symmetrical working chambers connected with a pump chamber which is actuated by a PZT diaphragm. The flows in the device are simulated using OpenFOAM and actual performance of the device is experimental investigated. Generated flow with velocity of up to 1.0 m/s (at driving voltage of 10 Vpp) was verified by the hotwires embedded in each working chamber. The finding form this study can contribute to the development of multi-axis fluidic inertial sensors, fluidic amplifiers, and gas mixing, coupling and analysis.

In this paper, we present the experimental and numerical development of a millimeter scale device that produces four micro-jet flows comprising two perpendicular pair. In addition, we show numerically the ability to employ these micro-jets for MEMS based fluidic angular rate sensor. The jets were created in a closed fluidic network without a check valve, and they can freely deflect in a confined sensing chamber. This allows the application of these jets to a triple-axis angular rate sensor whose working principle relies on the deflection of a jet in a rotating frame. The triple-axis angular rate sensor can be designed with only four thermal sensing elements. Our work can also be adapted to help researchers quickly develop a prototype or to integrate an inertial sensing component in their own micro-fluidic, micro-bio, or lab-on-a-chip systems.

This paper presents the development of a dual-axis gas gyroscope, whose working principle is based on the convective heat transfer and thermoresistive effect of lightly doped silicon. The working principle and the cross-sensitivity of the gas gyroscope are also analyzed. Experiments were performed to confirm the simulation results and good agreement has been achieved. The measured sensitivities for the X-axis and Y-axis were 0.107 mV deg−1 s−1 and 0.102 mV deg−1 s−1, respectively. Compared with a gyroscope of the same configuration but using tungsten as a sensing element, this gyroscope has 42 times greater sensitivity and one quarter the power consumption. These advantageous characteristics are inherited from the high TCR and high resistance of lightly doped p-type silicon. Nonlinearity and cross-sensitivity were measured to be smaller than 0.07% FS and 0.5% FS, respectively. The effect of acceleration on the sensitivity is 0.02 (deg s−1)/g and the measurement resolution based on sensitivity and noise analyses is 0.05 deg s−1. The relations between sensor performance, power consumption and ambient temperature were also realized.

This paper presents the study on displacement valveless micropump which is actuated by electromagnetic force on a permanent magnet embedded in PDMS diaphragm. The network channel of the present pump includes two inlets and one outlet channels forming an intersection in front of a pump chamber. Two designs of the pump with different structure of the inlet channels are investigated. One structure of the inlet is curved around the pump chamber (type I) and the other is straight channels (type II). Both types of pump are in one layer structure. The numerical simulation results show that Type I produces larger flow rate than that of Type II. However, at small deflection of the diaphragm, the difference in flow rates between two pumps is not much. Type I shows a clear advance pump performance in comparison with Type II when deflection becomes large. Type I has been fabricated by MEMS technology for experiment study. The fundamental characteristics of the pump have been validated. The flow rate of up to 1.2 mL/min was obtained at driven frequency of 30Hz and applied current of 35 mA.

The paper reports on characterization of piezoresistive coefficients and Seebeck effect of aligned single wall carbon nanotube (SWNT) forest film. The film was synthesized by water-assisted chemical vapour deposition (CVD), a process known as “super growth”. CNT film was condensed, manually maneuvered and conveniently patterned by EB lithography to form desirable shapes. The piezoresistive coefficient was found to be two times of that of conventional bulk silicon counterpart. Measurements on Seebeck effect of the thermocouple made of Au-CNT films showed an output voltage of 7.5µV/°C. These devices were fabricated on a same silicon substrate with a single CNT film.

A gas-jet micro pump with novel cross-junction channel has been designed and fabricated using a Si micromachining process. The valveless micro pump is composed of a piezoelectric lead zirconate titanate (PZT) diaphragm actuator and fluidic network. The design of the valveless pump focuses on a cross-junction formed by the neck of the pump chamber and one outlet and two opposite inlet channels. The structure of cross-junction allows differences in fluidic resistance and fluidic momentum inside the channels during each PZT diaphragm vibration cycle, which leads to the gas flow being rectified without valves. The flow channels were easily fabricated by using silicon etching process. To investigate the effects of the structure of the cross-junction on the gas flow rate, two types of pump with different cross-junction were studied. The design and simulation were done using ANSYS-Fluent software. The simulations and experimental data revealed that the step-nozzle structure is much more advantageous than the planar structure. A flow rate of 5.2 ml/min was obtained for the pump with step structure when the pump was driven at its resonant frequency of 7.9 kHz by a sinusoidal voltage of 50Vp-p.

This paper proposes a new valve-less pump with cross-junction channels and integrated hotwires. The pump was actuated by PZT diaphragm to create a gas jet flow for fluidic application. The design and simulation are based on transient fluidic analysis with experimental result of PZT diaphragm so that features of micropump is predicted with high reliability. Two designs of the pumps with different nozzles were investigated to study 3D nozzle effect. The micro pump was fabricated by standard MEMS process. Experiment was performed and agreement has been achieved between simulated and experimental results. The flow rate of 4.3sccm was achieved at the driving voltage of 40 Vpp in frequency response of 7.9 kHz. The discharge pressure of 0.18 kPa was measured at 40 Vpp and the output voltage of the hotwire was 1.07V at the constant applied voltage of 0.4mA

This paper presents a novel approach for considerably enhancing the sensitivity of piezoresistive microcantilever-type acceleration sensors. The design, fabrication and characterization of an ultra miniature single crystal micro acceleration sensor with Nanometer Stress Concentration Region (NSCR) on piezoresistors utilizing bulk micromachining techniques and Focus Iron Beam tool (FIB) have been discussed. Finite element simulations indicate an increase in sensitivity compared to a conventional microcantilever beam with the same thickness by a factor of 8.6. Devices have been fabricated and initial characterization has been performed. The new design shows an increase in the relative resistance change compared to a microcantilever with the same thickness and conventional piezoresistor design.