A Robust and Sensitive Silicon-MEMS Tactile-Imager with Scratch Resistant Surface and Over-Range Protection

Abstract

In this paper, a robust and sensitive silicon-MEMS tactile-imager which realizes scratch resistance and over-range protection is presented. This concept of tactile-imager can solve the fragility problem of sensitive structure without any protective materials, using backside silicon surface as contact-face. Also, backside contact-face is very suitable for tactile sensors since electronic terminals in the circuits can be removed from the contact-face side. Fabricated tactile-imager showed high robustness in scratch resistance tests with #120 emery-papers. In addition, over-ranged input ( 1.68N) applied to 10O[m-silicon diaphragm was safely received. Robustness of the tactile-imager has been much improved using the concept without degradation of the original force sensitivity and spatial resolution.

Three dimensional surface-shape tactile imager with fingertip-size silicon integrated sensor-membran

“…On the circuit side, pixel array including strain sensor for 3D surface-shape imaging are integrated by silicon integrated circuit technology. Although square-shape membranes in previous study [5][6][7] have succeeded to realize various functions in tactile imaging, they have some problems on robustness and uniformity of sensitivity. Figure 2 shows FEM simulation results for robustness comparison of square and circular shape sensor-membranes.…”

“…The sensor-membranes are fabricated by overall wafer thinning process developed in our previous study [7]. The thickness of the membrane is controlled to 10µm using the BOX layer for etching stop layer.…”

“…In order to realize both fine-pitch sensor pixel and surface flexibility, we have proposed and reported some silicon tactile-imagers with large silicon diaphragm integrated with pixel array of contact-force [5] and temperature sensors [6] on it. Also, robustness of the tactile sensors has been improved for scratching and over-range input [7]. However, the sensor membrane size was small (3mm-square), and the shape is rectangular which is insufficient on uniformity of sensitivity and anti-shock property of the diaphragm edge.…”

Three-Dimensional Silicon Smart Tactile Imager Using Large Deformation of Swollen Diaphragm with Integrated Piezoresistor Pixel Circuits

“…On the other hand, once over-ranged strain is applied, silicon is well known as a fragile material even though it has very good mechanical properties and large breaking stress in room temperature. Research to realize robustness of the silicon tactile imager has just started (Takao et al, 2007), and it will be a challenge to change silicon tactile imagers from a research target to practical sensing devices used widely in many fields.…”

Multi-functional Monolithic-MEMS Tactile Imager Using Flexible Deformation of Silicon IC

“…This dilemma has been a common and essential problem in silicon-MEMS tactile-imagers. Recently, we have proposed a robust and sensitive structure [10] which realizes scratch resistance and over-range protection keeping its original high performance for contact-force imagers. The new structure is applicable to design of the multi-functional tactile imager.…”