- Tactil Sensing: An 8 x 8 array of capacitor cells is utilized, giving the device 64 force sensitive tactile points. A capacitive based tactile sensor measures an applied force by detecting changes in the distance between two parallel plates of a small capacitor. As force is increased, the dielectric material between the plates will compress, increasing their effective capacitance.
- Thermal Sensing: A thermal sensor measures heat conduction by heating an object, and measuring the resulting temperature change at the sensor’s surface using a 4 X 4 array of surface mounted thermistors. To measure thermal conductivity, the sensor applies heat to a material, and measures the rate of temperature change at its surface. The cooling rate is proportional to the material’s thermal conductivity; a good heat conductor will rapidly reduce the sensor’s temperature, while a better insulator will have the oppositeeffect. <http://ieeexplore.ieee.org/iel5/8152/23643/01087566.pdf>

Castelli, F., "An Integrated Tactile-Thermal Robot Sensor With Capacitive Tactile Array," Prec. IEEE Transactions on Industry Applications, Vol. 38, No. 1, Jan./Feb. 2002, p. 85-90

- Tactil Sensing: The tactile sensing portion is composed of an 8 by 8 array of capacitive cells. Two parallel electrically conductive plates generate a capacitance that is a function of their separation. If a compressible dielectric is placed between them, a force applied to the top surface of the capacitor will reduce the plate separation distance. The resulting change in capacitance can be used to infer the applied force. This principle is the basis of the force transduction of the capacitive tactile sensor.
- Thermal Sensing: The thermal sensor has been obtained by the rows’ traces ofthe capacitive array. The spatial thermal resolution is obtained by the resistance of each of the 8 rows’ traces (2-mm spaced) detected by a multiplexing system. <http://ieeexplore.ieee.org/iel5/28/21119/00980361.pdf>

Shimizu, T., Shikida, M., Sato, K., Itoigawa, K., "A New Type of Tactile Sensor Detecting Contact Force and Hardness of an Object," Prec. IEEE International Conference on MEMS 2002, p. 344-347

A new type of tactile sensor that can detect both the contact-force and hardness of an object is proposed. It consists of a diaphragm with a mesa structure, a piezo-resistive displacement sensor on the diaphragm, and a chamber for pneumatical actuation. An array of these sensors can detect the two-dimensional contact-force-distribution and hardness-distribution information, and the surface texture of the contacted object.
- Contact-force distribution and 2D ,surface texture image detection: When the tactile sensor array makes contact with an object having a bumpy surface, the surface profile of the object causes some of the mesa structures on the diaphragms to contact the object, so their diaphragms deform downwards. From the displacement and location of the deformed diaphragms, the system can detect the contact-force distribution and 2D surface texture image of the object.
- Hardness distribution detection: In the second mode, the contacted mesa elements are pneumatically driven towards the object. The contacted regions of the object are deformed according to the driving force of the mesa element and the hardness of the object. Therefore, we can detect the hardness distribution of the object by measuring the relationship between the displacements of the diaphragms and the actuation force of the mesa elements. <http://ieeexplore.ieee.org/iel5/7726/21214/00984273.pdf>

Fiorillo, A., "A Piezoresistive Tactile Sensor," Prec. IEEE Transactions on Instrumentation and Measurement, Vol. 46, No. 1, Feb. 1997, p. 15-17

A simple, efficient and cost-effective tactile sensor has been described, with low spatial resolution, for robotic applications. The version described consists of sixteen pairs of piezoresistive strain gauges mounted on opposite faces of an equal number of metallic cantilevers. <http://ieeexplore.ieee.org/iel1/19/11995/00552150.pdf>

Kemper, M., "Development of a Tactile Low-Cost Microgripper with integrated Force Sensor," Prec. IEEE International Conferece on Control Applications 2004, p. 1461-1466

A novel tactile force-sensing microgripper is developed, which is based on a flexure hinge fabricated in stainless steel by wired Electro Discharge Machining (EDM). The gripper was equipped with a semiconductor strain-gauge and a piezo stack which generates a linear force proportional to a input voltage. <http://ieeexplore.ieee.org/iel5/9527/30193/01387581.pdf?arnumber=1387581>

-- YongLaePark - 02 Sep 2005