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This paper reports a sensor to directly measure the traction forces generated by migrating cells in a confined space. The sensor consists of an array of miniaturized piezoresistive cantilevers which are surrounded by a pluronic-F127 pattern. The pattern allows the self-alignment and directional migration of the cells to the cantilever array as the adhesion of cells to pluronic-F127 is poor. Our method...
This paper reports on a tactile sensor to measure normal force, tangential force and friction coefficient simultaneously. The proposed sensor is composed of three pairs of piezoresistive beams embedded in an elastomer. The normal and tangential forces can be measured by detecting the normal and shear deformations of the elastomer with the piezoresistive beams. The friction coefficient can be measured...
The paper reports on micro pillars with thin fluorocarbon layer formed onto their side walls and the surface of the substrate where the pillars are standing. Since the cell cannot adhere to the fluorocarbon layer, the cultured cells will adhere only to the top of the pillars. Therefore, the traction forces of the cells might be measured without considering their adhering positions. We fabricated micro...
This paper reports on a method to measure vibration occurring on the membrane of a mammalian cell which is subjected to ultrasound. The measurement is based on an array of piezoresistive MEMS force sensors. Experimental results with the fabricated sensors showed a change in frequency response to the ultrasound-induced vibration of NIH3T3 cells adhered to the fabricated sensor.
This paper reports a method to focus sound in liquid to a desired point using a PDMS-based varifocal acoustic mirror. We used PDMS-air boundary as a sound reflector to concentrate sound. By adjusting the curvature radius of the acoustic mirror, we could change the position where sound was concentrated. We confirmed that our method was able to improve the output of the acoustic sensor for different...
We measured flow velocity of swallowed liquid passing through pharynx. We put a pressure sensor on a palate to measure tongue pressure when swallowing the liquid. And we put two acoustic sensors on the neck skin in order to measure swallowing sound when liquid passes through the pharynx. From the output of these three sensors, we can know the timing of the liquid passing through each sensor points...
We proposed a thermo-acoustic transmitter in liquid using a metal heater covered with silicone oil. Our experiments showed that the structure of silicone oil on metal heater emitted stronger ultrasound compared to the structure of water on metal heater. However, when used in other liquid, the silicone oil must be encapsulated to prevent the mixing of the two liquids. We therefore proposed the device...
We report on the dynamic characteristics of a tactile sensor using a micro standing cantilever embedded in a silicone elastomer. Vibration test results show that the dynamic characteristics of the sensor, which is composed of a cantilever and a surrounding elastomer, depend on those of the elastomer part. Moreover, no matter how much the resonant frequency of the cantilever is, it can follow the oscillating...
We propose a CO2 gas sensor based on an impedance change of ionic gel (IG) according to the CO2 gas concentration. The sensor consists of an IG film patterned on electrodes. The impedance of the IG changes when the IG absorbs CO2 gas. CO2 gas concentration can be detected by measuring the amount of impedance change. Our proposal sensor has a merit that power consumption is very low (<1μW). It is...
We propose a skin-type tactile sensor with standing piezoresistive cantilever to detect micro size texture of object. By forming micro ridges to the sensor surface as a finger print, the sensitivity of the tactile sensor increased for micro texture scanning. This characteristic enabled the detection of 500nm high 300μm wide bumps arranged with 50μm pitch on a flat surface. This...
We propose a triaxial force measurement cantilever with piezoresistors fabricated by rapid thermal diffusion sidewall-doping. The device is developed as a tool for applying quantitative mechanical stimuli to cells and measuring their mechanical properties at the same time. The device consists of a sensing tip, two sensing beams, and four wiring beams. We form piezoresistors on the surface of the sensing...
This paper presents the design, fabrication, and the characterization of a photo-response compensated piezoresistive cantilever. The application field of the cantilever is to measure cellular mechanical properties under fluorescence microscopy. Photo-response which is caused by an excitation light of a fluorescence microscope interferes with measurement. We proposed piezoresistive cantilevers consist...
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