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Development of a bio-inspired MEMS based tactile sensor array for an artificial finger

Muhammad, Haseena Bashir (2012)
Ph.D. thesis, University of Birmingham.

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In this thesis, the design, fabrication and characterisation of a bio-inspired microelectromechanical systems (MEMS) based tactile sensor array is presented. A vast amount of research has been carried out in the area of tactile sensing and various transduction methods have been explored. However, currently no device exists with a performance comparable to that of the biological tactile sensors of the human fingertip in terms of robustness, sensitivity, spatial resolution and dynamic performance. The sensors developed in this work employ the principles of electrical capacitance and are fabricated from commercially available siliconon- oxide wafers using simple process steps. Each sensor is formed from two plates of highly conductive silicon separated by an air-gap formed from sacrificial etching of the oxide layer. Deflection of the 2 \(\mu\)m thick upper plate of the sensor as a result of applied mechanical stimulus, causes a change in capacitance which is the output of the sensor. Within the array, the individual sensors are spaced 150 \(\mu\)m apart (centre-centre pitch of 570 \(\mu\)m) and therefore offer the potential for high spatial resolution. To protect the sensor array from mechanical shock and provide skin like compliance, the use of suitable packaging materials was explored. The use of poly dimethyl siloxane (PDMS) as a suitable skin-like material was demonstrated. Modification of the surface topography of the packaging layer to include ’fingerprint’ like features was explored and its benefits highlighted. Sensor characterisation experiments revealed that the sensing device was sufficiently sensitive to allow the discrimination of different textures (with feature spacing down to 0.2 mm) through tests conducted using gratings varying in spatial periodicity and fabrics. Based on the results, the sensors can be used as an analogue of the slowly adapting tactile receptors (Merkel disks) for robotic finger applications.

Type of Work:Ph.D. thesis.
Supervisor(s):Ward, Michael C. L.
School/Faculty:Colleges (2008 onwards) > College of Engineering & Physical Sciences
Department:School of Mechanical Engineering
Subjects:QH301 Biology
QM Human anatomy
T Technology (General)
TJ Mechanical engineering and machinery
Institution:University of Birmingham
ID Code:3259
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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