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ABSTRACT: In this paper, we propose a sensor for measuring the three-dimensional (3D) velocity vector of airflows. The sensor, which was a 10 mm spherical figure, had a laminated structure with three channels fabricated inside. The components of the airflow velocity vector were measured respectively by three piezo-resistive cantilevers fabricated in each of the three channels. Experiments with a wind tunnel demonstrated that our sensor can measure not only the velocity amplitude but the 3D velocity direction as well.
Micro Electro Mechanical Systems (MEMS), 2011 IEEE 24th International Conference on; 02/2011
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ABSTRACT: In this paper, we propose a stretchable tactile sensor composed of a pair of silicone rubber channels filled with electro conductive liquid. When a force was applied to this channel, its length and cross-sectional area deforms. By measuring the resistance change of the electro conductive liquid in the channel, its deformation can be measured. The proposed tactile sensor is composed of two parallel channel filled with electro conductive liquid, therefore, by comparing the resistance changes of each channel to the deformation, only the contacting force can be measured independently. Since a liquid is used for the sensing material, the proposed liquid tactile sensor can be easily attached to movable portions as the joints of robots. In the paper, we measured the sensing characteristics of the liquid tactile sensor to the stretch, bend, and contact force. Finally, the efficiency of the sensor was demonstrated by measuring the contact force from 0 to 3.0N by attaching the 20% stretched liquid tactile sensor to curved surfaces with 0.05mm<sup>-1</sup> in curvature.
Robotics and Automation (ICRA), 2010 IEEE International Conference on; 06/2010
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ABSTRACT: Parylene films deposited on liquid surface induce film tension that changes the liquid shape. We observed that the force acting on the surface of Parylene-C encapsulated liquid bodies increased continuously during Parylene deposition process and reached final values of magnitude more than 700 ¿N/mm for a 1 ¿m thick film, 20 times larger than the surface tension of the encapsulated liquid. This surface force can only be attributed to the tension of the Parylene films. This founding requires that in design of Parylene encapsulated liquid structures, Parylene film tension must be considered as the main factor that determines the structures' final shape.
Micro Electro Mechanical Systems (MEMS), 2010 IEEE 23rd International Conference on; 02/2010
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ABSTRACT: We propose a force sensor based on gold nanoparticles, which enable optical detection of force by measurement of the scattering light spectrum. Gold nanoparticles were dispersed on an elastomer sheet. The scattering spectrum changes due to strain were observed to investigate applicability of the sensor to force measurement. The force deforms the elastomer sensor body, and increases the interparticle distance of gold nanoparticles on the sheet. The increase of the interparticle distance gives rise to the scattering characteristic changes. We fabricated a prototype sensor using PDMS sheet and 40 nm of diameter gold nanoparticles. It was demonstrated that 21% strain induced 60% increase of scattering intensity of gold nanoparticles.
Micro Electro Mechanical Systems (MEMS), 2010 IEEE 23rd International Conference on; 02/2010
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ABSTRACT: This paper reports on direct measurement of differential pressure on a butterfly wing during free flight. Differential pressure was measured using a micro-fabricated sensor. A piezo-resistive cantilever was used as a differential pressure sensor. The sensor was 1.0 mm à 1.0 mm à 0.3 mm in size and 0.7 mg in weight so that it did not interfere with wing motion. By attaching the sensor to the center of a butterfly forewing with a flexible wiring, the differential pressure on the wing was measured during ¿no flight flapping¿ and ¿taking off¿.
Micro Electro Mechanical Systems (MEMS), 2010 IEEE 23rd International Conference on; 02/2010
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ABSTRACT: Two main problems in the manipulation of objects with robot-hands are the control of the contact force and the planning of approaching motion. In this paper, we report on the three types of MEMS sensors for robots to detect the contact forces, slippage and the distance to the objects to realize dexterous manipulation of objects with robot-hands. As a tactile sensor, we propose standing piezoresistive cantilevers and beams embedded in PDMS or viscous liquid. Since the standing cantilevers and the beams deform with the PDMS, the contact force can be measured by the resistance changes of the structures embedded in the PDMS. Additionally, the viscous liquid around the cantilever becomes the high-pass filter to detect the time variation of the contact forces. Also, we propose a proximity sensor using ultrasonic reflection to detect the distance between robot-hands and the target objects for grasping. By integrating the proposed three types of MEMS sensors on a robot-hand, approaching and manipulation will be realized. This will enlarge applications of the future robot as an assistant of our daily life.
Solid-State Sensors, Actuators and Microsystems Conference, 2009. TRANSDUCERS 2009. International; 07/2009
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ABSTRACT: We report on a method to increase sensitivity of SPR (Surface Plasmon Resonance) sensor using nano-pillar structures as a protein adhesion site. The dense and tall nano-pillar array increases a virtual protein adhesion area within an SPR electromagnetic field (EMF) so that an SPR dip shift increases compared with a conventional SPR sensor. Fabricated silica nano-pillar chip with 200-nm-pitch and 570-nm-height pillar array was assembled with an optical prism with an Au film, and sensitivity enhancement for protein measurement by the nano-pillar was examined. The SPR measurement result exhibited a significant dip shift increase, about ten folds of that of the normal SPR device. The nano-pillar SPR has a potential of increasing sensitivity of SPR in detecting proteins.
Solid-State Sensors, Actuators and Microsystems Conference, 2009. TRANSDUCERS 2009. International; 07/2009
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ABSTRACT: This paper presents the design, fabrication, and the characterization of a stretchable substrate, achieving the change of intracellular calcium ion concentration by mechanical stress. We propose the stretchable substrate integrated with the air chambers of the pneumatic actuator. We have measured the areal strain depending on input pressure and the intracellular calcium ion concentration increase in response to the mechanical stress. The present stretchable substrate is able to provide the areal strain of 5.21% ~ 12.3% for the input pressure of 34.5 kPa ~ 103 kPa. We also verified that the present stretchable substrate is able to stimulate cells by the mechanical stress applied through integrins, showing potential feasible application for monitoring the calcium ion influx caused by the mechanical stress.
Micro Electro Mechanical Systems, 2009. MEMS 2009. IEEE 22nd International Conference on; 03/2009
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ABSTRACT: We propose a reflective display device using an array of encapsulated micro droplets of a room temperature ionic liquid mixed with pH indicator dyes. The array is embedded in and addressed by a passive matrix. Parylene-on-liquid deposition is employed to encapsulate the liquid droplet arrays. When applying current to each droplet, the liquid mixture changes its color, providing the ability to display a pixel of graphics information. Once changed, the droplets can be tuned back to their initial color by reversing the direction of the applied electric current. The on-off switching time is less than 0.5 s. The response speed of the devices is at least 2 Hz.
Micro Electro Mechanical Systems, 2009. MEMS 2009. IEEE 22nd International Conference on; 03/2009
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ABSTRACT: We propose an integration method for arranging LED bare chips on a flexible substrate to fabricate a multi-color LED display. LED chips (240 mum times 240 mum times 75 mum) which were arrayed on an adhesive sheet were transferred to a flexible circuit substrate using our temperature-controlled transfer (TCT) and self-wiring (SW) method. Using these methods, we demonstrated a 5-by-5 LED flexible device and a two-color (blue and green) LED device, and observed light emission from the LED chips.
Micro Electro Mechanical Systems, 2009. MEMS 2009. IEEE 22nd International Conference on; 03/2009
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ABSTRACT: This paper describes an integration method of bridging-structural single-walled carbon nanotubes (SWNTs) onto the flexible PDMS sheet by stamping transfer. Silicon microstructures and the SWNTs which directly synthesized between the gaps of the microstructures were lifted off by PDMS stamp sheets with high yield (97.8%) and accuracy (position error <100 nm). From the SEM observation of our transferred structures, we confirmed that our method could transfer the bridging-structural SWNTs on to the flexible materials without any damage to the SWNTs' bridging.
Micro Electro Mechanical Systems, 2009. MEMS 2009. IEEE 22nd International Conference on; 03/2009
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ABSTRACT: We propose a tactile sensor with standing cantilevers embedded in viscous liquid. The viscous liquid was covered with an elastic body. Since the micro cantilevers were kept free in the liquid, they can detect large shear forces without damaging. When shear forces were applied to the sensor surface, they deform the elastic body and the viscous liquid. Since the standing cantilevers follow deformations of viscous liquid, shear forces can be detected with resistance changes of the cantilevers. If the shear force was kept constant, the cantilevers in liquid return to their initial posture. From this mechanism, the proposed sensor can detect the change of shear forces without damaging. Since the standing cantilever in single liquid filter detect the force applied to its surface. It becomes difficult to detect the contact position with the proposed sensor. Therefore, we arranged channel in the liquid filter to control the liquid flow. By arranging standing cantilevers into the channel, the cantilever's resistance changes with the distance from the contact position. In this paper, we measured the relationship between the contact position and the resistance changes of the cantilevers arranged in channel.
Micro Electro Mechanical Systems, 2009. MEMS 2009. IEEE 22nd International Conference on; 03/2009
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ABSTRACT: This paper reports on an air pressure sensor for the measurement of the aerodynamic force on an insect wing. A piezoresistive cantilever was fabricated as a pressure sensor. The size of the cantilever was 250 mum times 200 mum times 0.3 mum. The sensitivity to air pressure was 0.29 times 10<sup>-3</sup> Pa<sup>-1</sup> below 2.0 kHz. By attaching the sensors on the prototype of an insect wing, pressure distribution over the surface were measured when the flow was both steady and unsteady.
Micro Electro Mechanical Systems, 2009. MEMS 2009. IEEE 22nd International Conference on; 03/2009
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ABSTRACT: We developed liquid luminescent flexible displays using electrochemiluminescent solution as deformable luminescent material. The solution consisted of ruthenium complexes as light emitting material and ionic liquid as nonvolatile solvent. We injected the solution, to pattern and seal it, into microfluidic cells between two flexible films of polyethylene terephthalate substrates with indium tin oxide electrodes. The light emitting area of one cell was 2times2 mm<sup>2</sup>. The gap between the electrodes was 100 mum. We measured the luminance of the cell during application of 50 Hz/4.0 Vpp (peak-to-peak value) rectangular waves of voltage in bent condition. The device was bent along the convex curvature with radii of 60, 30 and 20 mm. The luminance was reduced by only 30 % when the radius of cells are suitable for flexible displays because they can tolerate large deformation of bending.
Micro Electro Mechanical Systems, 2009. MEMS 2009. IEEE 22nd International Conference on; 03/2009
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ABSTRACT: This paper presents a micro liquid prism. Two flat transparent plates float on a liquid droplet and these plates serve as prism faces. The two plates are positioned automatically by surface tension, just by putting the plates on the ellipsoidal droplet. Therefore the proposed prism can be fabricated accurately in micro scale without difficulty. As the liquid and the plates are encapsulated by Parylene, the prism can retain its shape. The prism which faces were 400 mum in diameter and whole size was smaller than 1mm<sup>3</sup> was fabricated. The adequate function of the fabricated prism for Surface Plasmon Resonance (SPR) measurement was verified.
Micro Electro Mechanical Systems, 2009. MEMS 2009. IEEE 22nd International Conference on; 03/2009
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ABSTRACT: We developed the processing technique to form three-dimensionally coiled yarns of display elements from microfabricated organic displays on flat plastic foils in order to realize stretchable electronics. Three dimensional fabrics like sweaters have been much attention as elastic substrates for stretchable electronic devices, but the deposition and patterning of functional materials on the fabric are incompatible to planar process technique of MEMS. To solve this problem, we propose the fabrication technique where firstly display components are constructed on flat plastic foils and the foils are, then, processed to form them into coiled yarns. In detail of the process, organic electrochromic displays are fabricated on the releasable parylene films above the glass. The foils with displays are cut into yarns with dicing cutters and released from the glass. To make yarns stretchable, the resultant foils are spirally rolled around elastic core fibers, forming helical coiled structure. The stretch ratio of the fabricated yarn is tuned with its pitch angle, ranging from 1 to 2. Finally, we demonstrate the projection of the selected one pixel out of 4 pixels both before and after the yarn is stretched at its ratio of 1.3.
Micro Electro Mechanical Systems, 2009. MEMS 2009. IEEE 22nd International Conference on; 03/2009
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ABSTRACT: Three types of artificial butterfly wings were fabricated for investigating the morphological function of actual butterfly wings. They consist of a thin polymer membrane and micromolded polyurethane veins. The planar shape and venation of one type were the same as those of a swallowtail butterfly, and those of the other two were different. The effect of the distribution of stiffness over the wings by the veins on flight characteristics during free forward flight was investigated using an ornithopter and the three different types of wing. The overall aerodynamic coefficients were the highest for the wings with veins the same as those of a swallowtail butterfly, indicating that the veins enable slow forward flight.
Intelligent Robots and Systems, 2008. IROS 2008. IEEE/RSJ International Conference on; 10/2008
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ABSTRACT: We synthesized carbon nanotubes (CNTs) at the tips of commercial atomic force microscope (AFM) probes by chemical vapor deposition (CVD) process with applying an electric field. Applying the electric field during the CVD process increased the yield of AFM probes with CNTs at the tips (CNT-AFM probes). We formed a catalyst layer on the surface of AFM probes, and carried out the CVD process to synthesize CNTs. After the CVD process, we observed the tips of the AFM probes with a scanning electron microscope (SEM). The yield of CNT-AFM probes was about 52 %. The CNTs were determined by resonance Raman spectroscopy using a 488 nm argon ion laser. Observed Raman peaks were peculiar to single-walled carbon nanotubes (SWNTs). Then we obtained AFM images of a sample grating with the CNT-AFM probes. The CNT-AFM probes had higher horizontal resolution than standard commercial AFM probes.
Micro Electro Mechanical Systems, 2008. MEMS 2008. IEEE 21st International Conference on; 02/2008
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ABSTRACT: We propose an SPR (surface plasmon resonance) coupling device which can tune the coupling condition by changing a pitch of an Au grating. The Au grating was formed on a flexible polymer membrane. SPR could be coupled to the grating, and dependency of SPR dip angles on the grating pitch was investigated. It was successfully demonstrated that the SPR dip position could be tuned depending on the grating pitch change by membrane expansion on our device. Our device has also shown that the nano-scale grating pitch can be effectively controlled on a large mm-scale device.
Micro Electro Mechanical Systems, 2008. MEMS 2008. IEEE 21st International Conference on; 02/2008
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ABSTRACT: This paper reports a simple method of making a three dimensional arrangement of MEMS sensors. In this method, a convex polyhedron is made up by folding the development which consists of structural plates and elastic hinges, and MEMS sensors are attached to its surfaces. The angle between two adjacent plates is determined geometrically by the dimensions of structures and only gravity is used to fold the development. We designed and fabricated the half structure of a truncated icosahedron which is well-known as a soccer-ball-shape, and attached 3-axis tactile sensors to all of its surfaces. The diameter of fabricated structure was 12 mm.
Micro Electro Mechanical Systems, 2008. MEMS 2008. IEEE 21st International Conference on; 02/2008
