ESPCI web site
Présentation de L’ESPCI :
L’École Supérieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris) est la première école d’ingénieurs française au classement de Shangai (classe 300/400). Distinguée par 6 prix Nobel, elle allie recherche d’excellence (1 publication par jour), innovation (1 brevet par semaine, 3 start-up par an) et formation interdisciplinaire par la recherche. Elle accueille 400 élèves ingénieurs, 600 enseignants-chercheurs et chercheurs dans 9 unités mixtes de recherche et environ 100 agents de support de la recherche et de l’enseignement.
Description of the subject :
The skin is the largest organ of the human body, allowing humans to explore their environment through touch. Additionally, skin provides temperature sensing capabilities that help us understand our surroundings and avoid damaging temperatures.
The imitation of human skin’s sensory ability via electronics is raising great interest due to its potential for applications including human-robot interactions, prosthesis arms with lifelike sense of touch, drivers’ drowsiness detector, and heart monitori. With the ability to collect complex information about their surroundings using e-skins, robots could succeed in more dynamic and variable tasks, such as rescue missions or caring for the elderly . Used in prosthetics, synthetic skin could provide the ability to sense touch and temperature
for amputees and individuals with nerve damage. Sensoskins are also capable of monitoring health parameters such as pulse waveforms and temperature distributions.
In a recent work, we present capacitive sensor based on composite materials, especially designed to address the main mechanical and electrical weaknesses of existing sensors. We combine foam structures filled with conducting carbon black particles and an insulating layer. Due to the elastic buckling of the foam pores, these materials display a high pressure sensitivity at low stress. A small pressure variation induces large strain deformation of the conductive pores associated to huge variations of capacitance. Changes of capacitance in response to minute compression can be accurately measured without any electronic amplification. These materials are easy-to-make and low cost. We report unprecedented performances : for pressure lower than 2000 Pa, the sensitivity exceeds 35 kPa-1. The demonstrated sensitivity is at least 70 times greater than previously reported values. Moreover, this sensor consumes less than 220 pW/cm². They involve capacitance values of 100 pF which are easy to measure with low cost electronics.
In this project, we plan to improve the performances of these materials. The recently developed PDMS foamed layers have the sensitivity but are not capable of spatial resolution. To reach this aim, we will use two approaches. First a few millimetric spatial resolution will be provided by recovering the top of the material with a lattice of millimetric size electrodes. To enhance the spatial resolution, we will follow a biomimetic approach. In humans, the tactile perception of fine textures ( spatial case<200 micrometers) is mediated by skin vibrations generated as the finger scans the surface. The presence of a regular pattern at the surface of the finger operates a spectral filtering of the texture induced pressure modulation which induces a mode selection of the force fluctuations at a particular frequency. The amplitude of these force fluctuations can then become an order of magnitude larger than in the smooth case as shown by Debregeas. Detection of micrometric structure is then enhanced. In this project, we plan to use such strategy. A modification of the sensing surface with individually deformable pillars would be able to provide just that. Furthermore the current pressure sensors are made of PDMS which is not very wear resistant. We will explore the possibility to replace the PDSM with much more wear resistant polyurethane based materials. Emulsion based polyurethanes currently exist and with the correct surfactant it might be possible to invert he emulsion before final crosslinking and polymerization.
Post doc position : Team MIE/CBI ESPCI
A complete CV, publication list, a motivation letter and all additional documents or information that might be of interest. Any recommendation letters should be sent directly via email (to luca.demedici@espci.fr) by the reference person or you can provide contact information of the reference person while applying.
Contact annie.colin@espci.fr
Requirements : PHD diploma
Starting date : 1rst April 2019
Recruitment terms : 12 months CDD
Salary : according to professional experience