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This paper presents a power-generating sensor array in a flexible and stretchable form. The proposed device is composed of a woven structure that provides various features, including a capacitive tactile sensor, piezoresistive strain sensor, triboelectric energy harvester, and piezoelectric energy harvester. The device is implemented in a textile structure using functional threads implemented with lead zirconate, carbon nanotube, polydimethylsiloxane, and silver nanowire (Ag NW). A stretching force can be detected by measuring the resistance change in the Ag NW composite layer on each thread. Further, the magnitude and location of the vertical force can be detected by measuring the capacitance variation on each capacitive cell that is formed by the gap between two Ag NW layers at the crossing points of each weft and warp thread. For the energy harvesters, the maximum power was measured as 108 μW at 3 MΩ from the triboelectric energy harvesting when the device was pushed in the vertical direction. When a stretching force was applied, a maximum of 60.3 μW at 1 MΩ was measured from the piezoelectric energy harvester.

Nano-structured palladium (Pd) is advantageous in the sensitive detection of hydrogen because of its large surface area. However, the formation of Pd nanostructure is not easy but requires expensive and complicated processes. In this work, we proposed hydrothermal growing of nano-needles and its application to hydrogen gas sensor. In this way, the physical parameters of the nanostructures such as length and diameter can be easily controlled during the hydrothermal process. In addition, fast response time and high sensitivity can be obtained because the hydrogen gas can be easily absorbed into the thin Pd layer resulting in the fast and steep change of the conductance.

We propose a wide dynamic range capacitive force sensor with two wrinkle-structured elastomer layers as a dielectric layer. The sensor consists of electrodes on each substrate and two dielectric layers between them. The electrode is made of platinum and fabricated by using a lift-off process. The polyimide film is used as a substrate. Two wrinkle-structured dielectric layers, which are placed in perpendicular direction, are made by poly(dimethylsiloxane) (PDMS) replica molding process. With the pressure applied on the device, dielectric layers deform while decreasing distance between the electrodes and thus increasing the capacitance of the sensor. The orthogonally positioned wrinkled structures make possible to increase the dynamic range of the capacitive cell. The proposed capacitive sensor operates in the pressure range of 1 MPa with the maximum sensitivity of 0.06%/kPa.

We report a “dual nanostructures” where MnO 2 nano-hairs cover NiCo 2 O 4 nano-needles forming NiCo 2 O 4 @MnO 2 double nanostructures. The NiCo 2 O 4 @MnO 2 double nanostructures were synthesized by simple two-steps hydrothermal synthesis on the etched surface of nickel (Ni) wire. These structures were applied to form high capacity of fiber-shaped super-capacitor which was fully fabricated and demonstrated in this work.

This research developed a textile coil inductor, in which conductive yarn was wound spirally onto textile, and produced an energy harvesting module utilizing a cylindrical compression coil spring structure to allow a permanent magnet to spin in the center hole of the coil inductor. The study confirmed through a pilot test that the voltage increased as the number of laminated layers of the coil inductor increased. Five subjects were tested in the energy harvesting measuring experiment after producing a sports shoe insole-mounted energy harvesting module. While the subjects executed sports motions such as walking and running at five given frequencies, the peak-to-peak voltage was measured by an oscilloscope and the accumulated energy voltage of the calculated rms voltage (Vrms) and the peak power (㎼) were derived. The output voltage increased as the frequency increased and the average Vp-p (V) of the five subjects was 0.53 V, the average peak power (㎼) was 0.289 ㎼, and the Vrms (V) was 0.065 V. This research is significant in that it suggests the possibility of an energy harvesting module based upon the textile coil inductor emerging from the former shoes’ energy generator packaging method for heavy shoe types by developing a lightweight, flexible, and human-friendly footgear module structure.

Using glucose concentration as an inflammation responsive element, we newly established an enzymeless glucose sensor integrated with a chronically implantable peripheral nerve cuff electrode for continuous and in-situ monitoring of local inflammation. The glucose sensor integrated with a nerve cuff electrode was fabricated on a polyimide substrate side-by-side, then the glucose sensor and nerve cuff electrode were reversely folded, and were located inside and outside, respectively. The experimental results reveal that the electroplated black Pt working electrode of the glucose sensor shows an enhancive surface roughness factor of 16.41 and had a good distribution on the flexible polyimide surface, which exhibits distinctly enhanced electro-catalytic activity compared to that obtained with plain Pt. Amperometry and electrochemical impedance spectroscopy indicated that the fabricated sensor had a sensitivity of 7.17 μA/mM cm 2 , an outstanding detection limit of 10 μM, significant selectivity, and excellent recovery performance for enzymeless glucose detection. In order to evaluate the feasibility for inflammation monitoring in the immediate vicinity of the implantable peripheral nerve cuff electrode, the association of an evoked nerve signal recording and glucose concentration was investigated through ex-vivo test using the sciatic nerve of a SD rat.

In this paper, we proposed a dual-mode intraocular pressure (IOP) sensor that has two separated diaphragms to conduct the changes of inductance and capacitance, and we compared the sensor’s performance with that of the conventional single variable capacitive sensor (single-mode sensor). Both mode sensors were used to monitor the pressure in in vitro tests with multiple media and in in vivo tests with rabbits. First, we demonstrated that the sensitivities of two types of sensors tended to be different for in vivo and in vitro tests. This was the first known attempt to show changes in the sensitivity and responsivity of IOP sensors in in vivo tests. The sensitivity and phase dip of the dual-mode sensor exceeded that of the single-mode sensor, irrespective of medium due to isolation of capacitive sensor from medium. In this paper, we have provided the equations that were used to evaluate the improvement in sensitivity, and we have shown the coincidence with in vitro and in vivo tests. Based on the results we achieved, we believe that the dual-mode sensor is more feasible for use as an IOP sensor in in vivo tests, because its responsivity and sensitivity are superior to those of the conventional sensors. [2014-0379]

The development of low or room temperature gas sensors having a response towards a particular target gas becomes a fascinating research topic for low power consumption applications. In this paper, a sensitive room-temperature hydrogen sulfide (H2S) gas sensors based on hydrothermally synthesized undoped zinc oxide (ZnO) and Cu-doped ZnO (CZO) nanostructures decorated with reduced graphene oxide (RGO) are successfully demonstrated. A simple air-spray deposition is employed as an effective method for uniform GO decoration on CZO nanostructured film which is further chemically reduced to form RGO. The influence of Cu-doping on crystallinity, surface-morphological, and chemical compositional properties of the material have been systematically investigated. The gas sensing properties of the synthesized nanocomposite sensors have been studied towards H2S at room temperatures (∼24 °C). Compared with undoped ZnO/RGO, 3CZO/RGO nanocomposite sensor exhibited a better response towards H2S. The sensor response increases almost linearly with the increase in H2S gas concentration and exhibits the evident response of 0.87%–100 ppm H2S at 24 °C with the response and recovery time of 14 and 32 s, and a theoretical limit of detection of about 136 ppb. The enhancement was accredited to the collegial effect of both Cu dopant and RGO. The sensor also shows good selective behavior towards H2S against H2. The H2S sensing mechanism associated with the p-type behavior of the 3CZO/RGO sensor is also discussed at length.

This paper demonstrates a polyimide nerve cuff electrode with a controllable drug loading/release function for stable recording of peripheral nerve signals and stimulation and minimizing inflammation. For control of anti-inflammatory drug loading/release, dexamethasone (DEX)-loaded poly L -lactic acid (PLLA) and/or poly lactic-co-glycol acid (PLGA) nanofibers were deposited on a functional nerve cuff electrode by the electro-spinning method, which can control the weight of DEX loading on the functional nerve cuff electrode. Then, UV patternable polyethylene glycol (PEG) was coated on the functional nerve cuff with DEX-loaded nanofibers for the acceleration of the release rate of the drug. Through high performance liquid chromatography (HPLC), DEX release rates were increased from 16 to 28% (PLLA-loaded nanofibers) and from 68 to 87% (PLGA-loaded nanofibers) due to the increased diffusion rate of DEX after 28 days, respectively. In addition, the functional nerve cuff electrode was electro-polymerized with poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) as a conductive polymer in order to recover the decreased electrical properties caused by PEG patterning. The impedance measured at 1 kHz was 342 Ω mm2, which was extremely lower than the value of 1046 Ω mm2 of PEG-patterned cuff electrodes. Through the acute ex-vivo test of SD rat's sciatic nerve, the functional nerve cuff electrode with PEDOT:PSS exhibited stable and effective recording of the nerve's signals despite PEG patterning.

Multimodal tactile display systems that are capable of delivering versatile tactile information effectively are of great interest for virtual reality and tele-operation applications. In this paper, we present a new flexible multimodal tactile display system that delivers shape and texture information simultaneously using a single actuator. The proposed tactile display is actuated by a combination of electromagnetic and pneumatic forces and thus exhibits high tactile force to deliver shape information and large vibration amplitude to deliver texture information. In addition, the proposed tactile display device was implemented on a flexible PDMS structure to allow for tight attachment on any curved body to transfer reliable tactile information. By applying a current pulse of 300 mA for 5 ms, we readily controlled the state of the tactile actuator and measured the actuation displacement of 900 μm and the generated force of 20.1 gf. The average vibration amplitude of 30 μm was measured over a wide dynamic range (25---650 Hz) with an applied current of 74 mA. Lastly, by delivering various tactile information to users, we verified the functionalities of the implemented 4 ? 1 multimodal tactile display array. User study results showed that the fabricated multimodal tactile display system successfully delivered both shape information with an accuracy of 73 % and texture information with an accuracy of 90 %. This work demonstrates the potential of our multimodal tactile display system for uses in various applications such as tele-operation, tactile communication, and visual presentation for visually impaired.

This paper presents the design and implementation of a pneumatic tactile display with a Flexible Printed Circuit Board (FPCB) based capacitive position sensor integrated for precise position control. The proposed tactile display was designed to stimulate human finger in tangential direction. The size of the fabricated display was 18 mm × 18 mm × 20 mm. The position control range was 2.5 mm for each x and y axis. The resolution of position control was estimated from three repeated experiments as 0.12 mm with feedback control. The hysteresis behavior of the proposed display observed before feedback control has been eliminated.

This study demonstrates a polyimide nerve cuff electrode with a conductive polymer for improving recording signal quality at periph-eral nerve. The nerve cuff electrodes with platinum (Pt), iridium oxide (IrOx), and poly(3,4-ethylenedioxythiophene): p-toluene sul-fonate (PEDOT:pTS) were fabricated and investigated their electrical characteristics for improving recorded nerve signal quality. Thefabricated nerve cuff electrodes with Pt, IrOx, and PEDOT:pTS were characterized their impedance and CDC by using electrochemicalimpedance spectroscopy (EIS) and cyclic voltammetry. The impedance of PEDOT:pTS measured at 1 kHz was 257Ω, which wasextremely lower than the value of the nerve cuff electrodes with IrOx (15897 Ω) and Pt (952Ω), respectively. Furthermore, the chargedelivery capacity (CDC) of the nerve cuff electrode with PEDOT:pTS was dramatically increased to 62 times than the nerve cuff elec-trode with IrOx. In ex-vivo test using extracted sciatic nerve of spaque-dawley rat (SD rat), the PEDOT:pTS group exhibited higher sig-nal-to-interference ratio than IrOx group. These results indicated that the nerve cuff electrode with PEDOT:pTS is promising foreffective implantable nerve signal recording.Keywords: Nerve cuff electrode, Neural signal recording, Iridium oxide, PEDOT:pTS, ex-vivo test

In this paper, we propose a three-axis pneumatic tactile display that is precisely controlled by using integrated capacitive displacement sensors. The proposed tactile display consists of a core body with a 3 × 3 balloon array on its top surface, four lateral balloons made of latex rubber, and inner and outer frames that include capacitive displacement sensors based on a flexible printed circuit board. The 3 × 3 balloon array on the core body is designed to apply normal haptic stimulation to a human fingertip. In addition, the lateral motions of the core body and each frame produce haptic stimulation in a tangential direction. Precise control of lateral motion was achieved by feedback control using the capacitive displacement sensors. The size of the fabricated tactile display was 26 × 26 × 18 mm3. We experimentally performed manipulation of the proposed device with a custom control system, thereby demonstrating accurate control of displacement.

We had presented an inductive type intraocular pressure sensor (L-sensor) in previous work. The distance between a micro coil anda ferrite on the membrane was modulated by pressure, and as a result the inductance and resonant frequency were changed. However,L-sensor has some problems to implant in eyes. First problem is low sensitivity. When L-sensor was implanted in rabbit’s eyes, resonantfrequency of L-sensor was very hard to detect. Second problem is biocompatibility. Size of L-sensor is 6×7×1.2 mm. When L-sensorwas implanted in the eyes, it caused the inflammation. Therefore, this study suggests an inductive and capacitive type IOP sensor (LC-sensor). The sensitivity of the LC-sensor 27.3 kHz/mmHg under 60 mmHg. It is much larger than 14 kHz/mmHg of the L-sensor. Andthe size of LC-sensor is 47% smaller than L-sensor. After 2 weeks from the implantation of LC-sensor into rabbit eyes, we measuredthe changes of resonant frequency of LC-sensor according to increased IOP by Balanced Salt Solution (BSS) injection. As a result, thesensitivity of LC-sensor in in vivo test is 25 kHz/mmHg. That is similar to the sensitivity of in vitro test.Keywords: Glaucoma, Intraocular pressure (IOP), IOP sensor, in vivo, Wireless, Implantable

We propose flexible triboelectric energy harvester having a strain sensor property having hollow tube structure. The device was implemented by using flexible silicone tube where the silver nanowire layer is deposited on outer surface. When the tube is pressed or strained in axial direction, output power is generated by triboelectric effect. The output voltage and power of this device was measured as 23.4 V and 201 µW at 3 Hz. In addition, the device shows a piezoresistive property when longitudinal force is applied, which can be utilized as strain sensor that can be detected by measuring the resistance of the wires.

In this paper, we propose a modified frequency up-conversion mechanism to lower the operational acceleration level for energy harvesting devices using a snap-through buckling phenomenon. The proposed device consists of a buckled bridge beam clamped on flexible sidewalls with a proof mass and cantilever beams attached to the bridge. When subject to a vibration, the buckled bridge beam snaps through between two stable states, inducing impulsive acceleration on the attached piezoelectric cantilevers. During the snap-through transition, the flexible sidewalls deflect outward, thus lowering the threshold acceleration value for the state transition. Various sidewall materials with different flexibilities were tested to determine the maximum output power, bandwidth, and output characteristics for various input acceleration values. The minimum acceleration value for snap-through transition was 0.5g (g = 9.8 m/s2) when using latex sidewalls. A maximum output power of 0.4 mW Hz/cm2--that is 10 μW for test sample at an excitation frequency of 15 Hz--was generated by using the proposed device with latex sidewalls.

This paper proposes a tactile display providing both shear and normal feedback to the fingertip for generating three-axis tactile feedback during teleoperation of a surgical robot. The display is composed of five balloons actuated by controlling the pneumatic pressure. The implemented display is 18 mm × 18 mm × 15 mm. This size is suitable for mounting the display onto the master controls of a surgical robot. The maximum normal and shear displacements are 2 and 1.3 mm, respectively. The proposed tactile display may provide perceivable stimuli to a human finger pad in all five directions: normal, distal, proximal, radial, and ulnar. This paper also reports on the results of psychophysical measurement of the minimum perceivable movement of the developed tactile display for each of the five directions.

Electrostatic capacitors have high power density but low energy density. In contrast, batteries and fuel cells have high energy density but low power density. However, supercapacitors can simultaneously achieve both high power density and energy density. Herein, we propose a supercapacitor, in which etched nickel wire was used as a current collector due to its high conductivity. Two redox reactive materials, MnO2 nanoflakes and NiCo2O4 nanoneedles, were used in a hierarchical structure to cover the roughened surface of the Ni wire to maximize the effective surface area. Thus, a specific capacitance, energy density, and power density of 14.4 F/cm3, 2 mWh/cm3, and 0.1 W/cm3, respectively, was obtained via single-electrode experiments. A fiber-shaped supercapacitor was prepared by twisting two electrodes with solid electrolytes made of KOH and polyvinyl alcohol. Although the solid electrolyte had a low ionic conductivity, the energy density and power density were determined to be 0.97 mWh/cm3 and 49.8 mW/cm3, respectively.

We propose a fully liquid-based energy harvester that uses ferrofluid droplets as a movable dielectric material. The proposed device consists of top and bottom plates with conducting electrodes coated with a thin solid dielectric layer, a conducting liquid, and oil-based ferrofluid droplets as movable dielectric layers. The rotational motion of the ferrofluid droplets is actuated by a magnetic field that causes a capacitance variation that is used to generate electric power. An average output power of $19.3~\mu \text{W}$ is generated when eight ferrofluid droplets are used at a rotational speed of 180 r/min. [2014-0387]

This paper presents the design, fabrication, and experimental demonstration of an artificial hair sensor made of polymer materials. Long polymer hair structures embedded with flexible three-dimensional piezoresistive sensors were formed on a flexible substrate in two-dimensional arrays to detect an applied external force. The flexible piezoresistor was implemented using a carbon nanotube-polydimethylsiloxane (CNT-PDMS) composite prepared by the mixing of multi-wall carbon nanotubes with PDMS. A CNT-PDMS composite with high conductivity and a high gauge factor was obtained by increasing the CNT concentration in PDMS. In this study, we used a 13% CNT-PDMS composite for fabricating the sensing element that was embedded in the proposed hair sensor. The hair sensor is 4 mm in height and 700 μm in diameter. The implemented device shows a linear and sensitive response in the on-axis mode with a sensitivity of 2900 ppm/μm.

This paper discusses a flexible energy harvester that consists of a polyvinylidene fluoride film attached to a curved substrate in a shell shape for harvesting energy from human motion. The proposed harvester effectively converts mechanical energy into electrical energy during the fast state transition of the shell structure. The results of an experiment demonstrated that shell structures with various curvatures produce high output potential and consequently offer high output power in comparison to a simple flat structure. The single shell structure generates an output power of 0.87 mW at a folding angle of 80° and a folding and unfolding frequency of 3.3 Hz. In addition, fabric with embedded piezoelectric shell structures was designed as an energy harvester in a wearable platform. The fabric, worn on the elbow joints and fingers, generates a high output power of 0.21 mW in spite of slow and irregular motion.

Dopamine (DA) is one kind of neurotransmitter in central nervous system which is indicator of neural disease. For this reason, determination of DA concentration in central nervous system is very important for early diagnosis of neural disease. In this study, we designed micro electrode array and fabricated by MEMS technology. Furthermore, we fabricated 3-D conducting nanostructure on electrode surface for enhanced sensitivity and selectivity due to increased surface area. Compared with macro and normal micro electrode, the 3-D nanostructure modified micro electrode shows better electrical performance. These surface modified pin type electrode was applied to detect low concentration of DA and successfully detect various concentration of DA from 100 μM to 1 μM with linear relationship in the presence of ascorbic acid and uric acid. From these results, our newly designed electrode shows possibility to be applied as brain biosensor for neural disease diagnosis such as Parkinson's diseases.

This paper describes an energy harvester which uses triboelectric and piezoelectric effect simultaneously to harvest the mechanical energy. The vertical vibration is converted into horizontal force through the hinge structure to apply stress on woven piezoelectric films. In addition, the vertical motion induces the triboelectric energy generation due to the contact between top plate and woven structures. The nano structured metal and polydimethylsiloxane (PDMS) surfaces were used to enhance the triboelectric effect. The maximum output voltage of 24 Vp-p and 291 Vp-p was simultaneously obtained from the triboelectric and piezoelectric effects, respectively, during the device operation at 9Hz.

In this paper, we propose a skin attachable piezoelectric energy harvester which was implemented by using magnetic alignment of cobalt (Co)-doped zinc oxide nanorods (ZnO NRs) to enhance the piezoelectric effect. Co-doped ZnO NRs with ferromagnetic property can be easily obtained by hydrothermal process, and their uni-directional alignment can be obtained by applying external magnetic field. In addition, double layers of platinum (Pt) and graphene were deposited on the surface as a flexible and stretchable electrode with high electric conductivity. The maximum open-circuit voltage of 17.4 Vp-p and short-circuit current of 0.26 μA was obtained at 4 Hz folding/unfolding operations.

In this paper, we propose a simple and low-cost fabrication technique for patterning carbon nanotube (CNT) films on polydimethylsiloxane (PDMS), which can be used in flexible sensors and electronics. We demonstrate CNT patterning on both recessed and flat PDMS surfaces using a standard photolithography method. By this proposed technique, we were able to fabricate a CNT film, having a high flexibility and good conductivity, on a PDMS surface. A CNT pattern with a minimum feature resolution of 150 μm was obtained using the proposed fabrication technique. The sheet resistance of the CNT film on the PDMS surface was determined to be in the 100–280 Ω/sq range. The thickness and resultant resistivity of the CNT film can be easily controlled by controlling just the spray duration. Furthermore, the gauge factor of the proposed device is higher than that of metal and it increases as the thickness of the CNT film increases.

A new high speed AFM probe has been proposed and fabricated. The probe is integrated with PZT actuated cantilever realized in bulk silicon wafer using heavily boron doped silicon as an etch stop layer. The cantilever thickness can be accurately controlled by the boron diffusion process. Thick SCS cantilever and integrated PZT actuator make it possible to be operated at high speed for fast imaging. The resonant frequency of the fabricated probe is 92.9 ㎑ and the maximum deflection is 5.3 ㎛ at 3 V. The fabricated probe successfully measured the surface of standard sample in an AFM system at the scan speed of 600㎛/sec

In this paper, we propose and demonstrate a transparent and flexible capacitive tactile sensor which is designed for multi-touch screen application with force sensing. A sensor module is composed of 2D array tactile cells with a spatial resolution of 2 mm to measure the touch force at multiple positions. The device is fabricated by using transparent materials on a transparent plastic substrate. The optical transmittance of the fabricated tactile sensor is approximately 86% in the visible wavelength region, and the maximum bending radius is approximately 30 mm. The cell size is 1 mm × 1 mm, and the initial capacitance of each cell is approximately 900 fF. The tactile response of a cell is measured with a commercial force gauge having a resolution of 1 mN. The sensitivity of a cell is 4%/mN within the full scale range of 0.3 N.

This paper presents the design, fabrication, and characterization of a microfluidic biochip with integrated actuation electrodes used to manipulate a cell and a microbead by dielectrophoresis and sensing electrodes to detect the trapping by using the impedance detection method. Combining deflective dielectrophoretic barriers with controlled pressure-driven liquid flows allows the accurate control of a cell/microbead in suspensions. The threshold voltage for microbead trapping was experimentally verified at various flow rates. The impedance change caused by the blockage of the electrical conducting path between sensing electrodes with the trapping of an MCF7 cell and a polystyrene microbead was measured. The impedance before the trapping of an MCF7 cell was 10.9 MΩ at 1 kHz and increased to 12 MΩ when the cell was placed between sensing electrodes.

This paper reports on a multifunctional microwell plate developed for lab-on-a-chip applications, such as high-throughput cell assay, drug screening, and microbead-based analyses. The proposed device was designed to provide three consecutive functions: the autonomous capture of biomaterials into multiple microwells in a two-dimensional array; active physical sealing of the microwells for isolation; and specific chemical injection into each microwell. The device was implemented with microfabrication technology using polydimethylsiloxane (PDMS) structures on a silicon or glass substrate. The multiple functions of the microwell plate were successfully demonstrated in an experiment using microbeads. The parallel positioning of live cells (CHO DG44) in multiple microwell arrays was achieved, as well as the independent injection of foreign solution into a specific target cell. Also the proposed microwell plate was utilized to capture microbeads, for antibody injection into each microwell, for quantum dot (QD) injection, and for fluorescence detection for a feasible demonstration of a microbead-based assay.

This paper presents a power-generating sensor array in a flexible and stretchable form. The proposed device is composed of resistive strain sensors, capacitive tactile sensors, and a triboelectric energy harvester in a single platform. The device is implemented in a woven textile structure by using proposed functional threads. A single functional thread is composed of a flexible hollow tube coated with silver nanowires on the outer surface and a conductive silver thread inside the tube. The total size of the device is 60 × 60 mm² having a 5 × 5 array of sensor cell. The touch force in the vertical direction can be sensed by measuring the capacitance between the warp and weft functional threads. In addition, because silver nanowire layers provide piezoresistivity, the strain applied in the lateral direction can be detected by measuring the resistance of each thread. Last, with regard to the energy harvester, the maximum power and power density were measured as 201 μW and 0.48 W/m², respectively, when the device was pushed in the vertical direction.

In this paper we propose a microfluidic chip that measures the mechanical stiffness of cell membrane using impedance measurement. The microfluidic chip is composed of PDMS channel and a glass substrate with electrode. The proposed device uses patch-clamp technique to capture and deform a target cell and measures impedance of deformed cells. We demonstrated that the impedance increased after the membrane stretched and blocked the channel.

This paper reports a new fabrication method of polydimethylsiloxane (PDMS) microlenses with various curvatures by using a water-based mold. The hydrophobic surface of Polypropylene (PP) substrate was modified by corona discharge using tesla coil to have hydrophilic surface. Then hydrophilic surface of PP substrate takes hydrophobic recovery to have various contact angles from less than to about . By using the water droplets with various contact angles as replica molds for PDMS process, we could obtain PDMS microlenses with various curvatures.

This paper demonstrates a new method of implementing complex microchannels in PDMS, which is simply constructed using three-dimensional photoresist structures as a master mold for the PDMS replica process. The process utilizes UV-insensitive LOR resist as a sacrificial layer to levitate the structural photoresist. In addition, the thickness of photoresist structures can be controlled by multi-step UV exposure. By using these techniques, various three-dimensional photoresist structures were successfully implemented, including the recessed cantilevers, suspended bridges, and the complex plates with micro-pits or micro-villi. We demonstrate that the three-dimensional photoresist structures are applicable to implementing complex multiple microchannels in PDMS by using the PDMS replica method.

In this study, we propose tactile sensors array in fabric form where an energy harvester and tactile sensors are integrated as a single device. The device is composed of flexible hollow tubes, piezoelectric straps and polyethylene terephthalate (PET) films. The hollow tubes and piezoelectric PVDF straps are woven by forming a fabric form. We present the measured output power during energy harvester mode and tactile sensor response during sensor mode.

We propose a liquid-based electrostatic energy harvester that uses ferrofluid droplets. The proposed device consists of top and bottom plates with conducting electrodes coated with a solid dielectric layer, a conducting liquid, and oil-based ferrofluid droplets. Using an external magnetic field, we experimentally verified the surfaces on which the ferrofluid actuates well. In addition, we investigated the rotational motion of ferrofluid droplets on Parylene C surface by adding surfacetant of conducting liquid.

This paper describes a custom-designed microfluidic chip for sensitive detection of antibody using quantum dot fluorescence in a microbead-based assay. The microfluidic chip is designed to isolate a single microbead where the binding reaction of antibodies happens on the surface. The microfluidic chip is fabricated on a glass substrate using transparent silicone elastomer, PDMS, for easy access to monitoring and flexible gate operations to capture the single microbead. For antibody detection, a sequence of functionalized assay has been performed in the fabricated chip including: capturing of microbeads; antibody injection into a micro-chamber; quantum dot injection; and fluorescence detection. Various concentrations of antibody have been tested and have shown good agreement with correlated fluorescent intensities.

This paper reports a new technology to implement complex PDMS microchannels, which are simply constructed using three-dimensional photoresist structures as mold for PDMS replica process. The process utilizes LOR resist as a sacrificial layer to levitate the structural photoresist and multi-step exposure to control the thicknesses of photoresist structures. Various shapes of photoresist structures were successfully fabricated. Using the PDMS replica method, the three-dimensional photoresist structures are demonstrated to be applicable for implementing complex microchannels in PDMS. In addition, more complex multilevel microchannels are constructed by bonding two PDMS layers with just single PDMS alignment.

The oscillating behaviour of TGS813 and TGS203S sensors in hazardous gases such as LPG and CO was studied under the oscillating conditions of rectangular wave, applied voltage 5 V, and duty ratio as 30 s/(3 0s+2 0 s). It was shownthat the oscillating behaviour was obviously different with the two type sensors. The data features were extracted by using Fourier and wavelet transform (WT). There were some very obscure differences among the amplitudes in fast Fourier transform (FFT) under different concentrations of LPG or CO. Further FFT analysis showed that it was difficult to discriminate between 800 ppm LPG and 800 ppm CO because of very little difference in the frequency content. By comparison, the corresponding coefficient plots in continuous wavelet transform (CWT) were investigated, and the original signal was also decomposed into coarse approximation A1 and five detailed information D5–D1. The results showed that the WT was more appropriate than FFT for the frequency–time problem.

We present a microfluidic chip designed for the detection of antibody by using quantum dots fluorescence and a microbead-based assay. A custom designed PDMS microfluidic chip with multi-layer channel is utilized for capturing microbeads; antibody injection into each micro-well; QD injection; and fluorescence detection. The experiment using the fabricated microfluidic chip has been performed on solutions with various concentrations of antibody and has shown correlated fluorescent intensities.

This article reports in situ FTIR monitoring of electrochemical reactions using a silicon-based thin-layer cell realized by micromachining fabrication technologies. The proposed device contains a silicon micromachined cavity cell integrated with a gold working electrode, a counter electrode, and a Ag/AgCl reference electrode. Electrochemical, spectroscopic, and spectroelectrochemical characteristics of the fabricated cell have been experimentally measured and exhibited a comparable performance to commercialized CaF2 thin-layer cells. In situ spectroelectrochemical characteristics have been successfully tested for both 2 mM K3Fe(CN)6 in an aqueous solution and 2 mM ferrocene in a dichloromethane solution using the fabricated thin-layer cell.

Square Wave Anodic Stripping Voltammetry (SWASV) was combined with microfabricated microelectrodes to analyze metal ions in aqueous solution and showed excellent performance such as short analysis time about 1 min per experiment, simultaneous detection of several ions and very low detection limit as low as several nanomoles per liter (i.e. sub-ppb in mass) without any of supporting electrolyte and stirring during analysis. Nafion, a famous ion-exchanging polymer, was introduced to protect the electrode surface from obstructing materials. The Nafion-coated microelectrode was free from disturbing impurities and was capable of analyzing natural water samples directly. Results from the direct water analysis showed similar performance to those from pre-treated samples in both sensitivity and analysis time. To secure the reproducibility of Nafion-coated electrode, a simple electrochemical cleaning method with potential sweep was used and the electrode remained reliable to continued experiments. Nafion-coated microelectrodes were further examined via the comparison with ICP–MS data.

In this paper, we report a miniaturized low-power wireless remote environmental monitoring system. This system has been developed for on-site monitoring of water pollution by heavy-metal ions. The system is composed of three parts: an electrochemical sensor module using microfabricated electrodes for detecting heavy-metal contamination in sample water; a custom potentiostat module including readout circuitry, analog-to-digital converter and microcontroller; and a radio frequency (RF) module for sending detected signals to a base station through wireless communication. The electrochemical sensor module is implemented using microfabricated mercury working electrodes (WEs), solid-state reference electrode (SSRE), and platinum counter electrode (CE). For the low-power operation, direct frequency-shift keying (FSK) modulation and simple binary FSK demodulation methods are used for RF module which is realized using 0.18 μm CMOS technology. All the modules are hybrid integrated in a printed circuit board (PCB) and low-power consumption below 1 mW has been achieved.

In this paper miniaturized disposable micro/nanofluidic components applicable to bio chip, chemical analyzer and biomedical monitoring system, such as blood analysis, micro dosing system and cell experiment, etc are reported. This system includes various microfluidic components including a micropump, micromixer, DNA purification chip and single-cell assay chip. For low voltage and low power operation, a surface tension-driven micropump is presented, as well as a micromixer, which was implemented using MEMS technology, for efficient liquid mixing is also introduced. As bio-reactors, DNA purification and single-cell assay devices, for the extraction of pure DNA from liquid mixture or blood and for cellular engineering or high-throughput screening, respectively, are presented.

In this paper, we first report a micropump actuated by surface tension based on continuous electrowetting (CEW). We have used the surface-tension-induced motion of a mercury drop in a microchannel filled with an electrolyte as actuation energy for the micropump. This allows low voltage operation as well as low-power consumption. The micropump is composed of a stack of three wafers bonded together. The microchannel is formed on a glass wafer using SU-8 and is filled with electrolyte where the mercury drop is inserted. The movement of the mercury pushes or drags the electrolyte, resulting in the deflection of a membrane that is formed on the second silicon wafer. Another silicon wafer, which has passive check valves and holes, is stacked on the membrane wafer, forming inlet and outlet chambers. Finally, these two chambers are connected through a silicone tube forming the complete micropump. The performance of the fabricated micropump has been tested for various operation voltages and frequencies. We have demonstrated actual liquid pumping up to 70 /spl mu/l/min with a driving voltage of 2.3 V and a power consumption of 170 /spl mu/W. The maximum pump pressure is about 800 Pa at the applied voltage of 2.3 V with an operation frequency of 25 Hz.

Proposed is a helical piezoelectric structure for a highly stretchable energy harvester to be applied on the human body. The proposed device consists of two counter-wound helical structures around a zcore structure made of an elastic fabric string. The inner fabric helix is used to separate the outer piezoelectric helix from the core to obtain a highly stretchable device. When stretched by 60% of its initial length, the device generates a maximum output voltage and power of 140 Vp-p and 0.6 mW, respectively, at an operation frequency of 4 Hz.

In this research, we developed wireless, inductive, pressure sensors with high sensitivity and investigated the effects of the inner materials (copper or ferrite) on the performance of the sensors. The proposed sensor is comprised of two parts, i.e., the top and the bottom parts. The top part includes a micro coil and a capacitor for the wireless transfer of data, and the bottom part includes the inner materials and a thick or thin flexible membrane to induce changes in the inductance. An anchor is used to assemble the top and bottom parts. The behavior of the sensor with copper was based on the eddy current effect, and, as the pressure increased, its resonance frequency increased, while its phase depth decreased exponentially. The principle of the sensor with ferrite was related to the effective permeability between a ferrite and a coil, and its response was the opposite of that with copper, i.e., as the pressure increased, the resonance frequency decreased linearly, and the phase depth increased linearl...