Fabrication of a Smart Suspension Structure of Micro Tactile Probing

Abstract

Abstract In micro tactile probing a design trade off must be made between stiff and robust probes. Stiff probes are capable of overcoming surface attraction forces, while delicate flexible probes are capable of making contact with a sensitive part without causing damage. To address this need for both flexible and stiff sensors a novel micro tactile probe has been proposed that makes use of an active suspension structure to modulate probe stiffness as required. In this paper we focus on the initial manufacturing process development of such a sensor. While initial design concepts were created with high precision machining techniques in mind, these are shown to have some fundamental limitations with respect to this specific application. Therefore a design for manufacture strategy was adopted and the structure of the initial design was modified such that it may be manufactured using a chemical etching based process. This paper presents the process followed to successfully adapt an initial sensor design for a chemical etching based manufacturing. Surface 3D microscopy was used to analyse the resulting structure, to demonstrate a significant improvement in device flatness. In addition Finite Element Analysis (COMSOL) was used to estimate the vertical and torsional frequency for the suspension structure which is compared with experimental measurements using a laser vibrometer to show good agreement.