Development of a flexible three-axis tactile sensor based on screen-printed carbon nanotube-polymer composite

Abstract

A flexible, three-axis carbon nanotube (CNT)–polymer composite-based tactile sensor is presented. The proposed sensor consists of a flexible substrate, four sensing cells, and a bump structure. A CNT–polydimethylsiloxane (PDMS) composite is produced by a solvent evaporation method, and thus, the CNTs are well-dispersed within the PDMS matrix. The composite is directly patterned onto a flexible substrate using a screen printing technique to fabricate a sensor with four sensing cells. When a force is applied on the bump, the magnitude and direction of force could be detected by comparing the changes in electrical resistance of each sensing cell caused by the piezoresistive effect of the composite. The experimentally verified sensing characteristics of the fabricated sensor exhibit a linear relationship between the resistance change and the applied force, and the measured sensitivities of the sensor for the normal and shear forces are 6.67 and 86.7%/N for forces up to 2.0 and 0.5 N, respectively. Experiments to verify the load-sensing repeatability show a maximum 2.00% deviation of the resistance change within the tested force range.

Emerging Material Technologies for Haptics

“…It is challenging to realize multilayer, complex devices using this method. Consequently, it is most widely used for simple devices, such as flexible and wearable devices . Yun et al fabricated a cellulose based electroactive paper for haptic applications using screen printing methods .…”

“…The conductive ink comprised silver paste screen printed onto the surface of the metallic film. In another approach, Pyo et al screen printed a CNT‐PDMS layer on a microfabricated Si/SiO 2 /Au substrate …”

Direct Imprint of Optical Functionalities on Free‐Form Chalcogenide Glasses

“…PDMS‐ nanotube composite mold : Multiwall Carbon Nanotubes (Cheep Tubes Inc.) were first dispersed in toluene using a probe sonicator. In parallel, PDMS (Sylgard 184, Dow Corning) was diluted in toluene (2:1) and was placed in an ultrasonic bath for 1 h. The two solutions were mixed and sonicated in a probe sonicator for 1 h. The mixture was then placed in a rotary evaporator for the evaporation of the toluene from the solution . Finally, a curing agent was added to the PDMS‐MWCNT solution and manually mixed for 10 min.…”

PDMS/MWCNT-based tactile sensor array with coplanar electrodes for crosstalk suppression

“…Currently, tactile sensors with high sensitivity and flexibility exhibit good prospects in various applications such as artificial limbs, robot skin, touch screens, and wearable electronics. Normally, the operating mechanisms for tactile sensors can be divided into five categories: piezoelectric 1,2 , triboelectric 2 , optical 3,4 , capacitive [5][6][7][8][9][10][11] , and piezoresistive [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] . Because of the inherent stiffness of conventional piezoresistive materials, many piezoresistive tactile sensors are fabricated with the combination of flexible polymer materials such as polydimethylsiloxane (PDMS) and polyimide.…”

“…Furthermore, CNT-doped PDMS has been used as an important material for pressure sensing. Han et al 28 and Pyo et al 29 proposed the development of piezoresistive pressure sensors based on printed PDMS/CNTs, which could detect three-dimensional forces. Combined with the pressure distribution measurement system, a printed multiwalled carbon nanotube (MWCNT)-PDMS composite pressure sensor proposed by Gerlach et al 30 is promising to avoid unhealthy rollover patterns by monitoring the plantar pressure.…”