Maurizio Biso

Piezoelectric Polymer Transducer Arrays for Flexible Tactile Sensors

The paper focuses on the manufacturing technology of modular components for large-area tactile sensors, which are made of arrays of polyvinylidene fluoride (PVDF) piezoelectric polymer taxels integrated on flexible PCBs. PVDF transducers were chosen for the high electromechanical transduction frequency bandwidth (up to 1 kHz for the given application). Patterned electrodes were inkjet printed on the PVDF film. Experimental tests on skin module prototypes demonstrate the feasibility of the proposed approach and reveal the potentiality to build large area flexible and conformable robotic skin.

Actuators based on intrinsic conductive polymers/carbon nanoparticles nanocomposites

New polyaniline (PANi) synthesis was performed starting from non-toxic N-phenil-p-phenylenediamine (aniline dimer) using reverse addition of monomer to oxidizing agent, the synthesis allows to produce highly soluble PANi. Several types of doped PANi were prepared to be used on electromechanical active actuators. Different techniques were used to include carbon nanoparticles such as carbon nanotubes and graphene. Bimorph solid state ionic actuators were prepared with these novel nanocomposites using a variety of supporting polymers.

Improvement of tactile capacitive sensors of the humanoid robot iCub's fingertips

Humanoid robots use tactile fingertips to perform object manipulation. In this paper, an improved prototype of a tactile capacitive fingertip for the hands of the humanoid robot iCub is presented. In particular, a conductive silicone based material has been used to improve the characteristics of the capacitive sensor and an additional silicone foam layer has been also introduced in the sensor architecture to prevent behavior variation due to fingertip deterioration (e.g., caused by object manipulation). A characterization of the fingertip sensing behavior is presented. This work is funded by the European Commission as part of the project ICT-FP7-231500 RoboSKIN.

Improving dry carbon nanotube actuators by chemical modifications, material hybridization, and proper engineering

Low voltage, dry electrochemical actuators can be prepared by using a gel made of carbon nanotubes and ionic liquid.1 Their performance can be significantly improved by combining physical and chemical modifications with a proper engineering. We demonstrated that multi walled carbon nanotubes can be effectively used for actuators preparation;2 we achieved interesting performance improvements by chemically cross linking carbon nanotubes using both aromatic and aliphatic diamines;3 we introduced a novel hybrid material, made by in-situ chemical polymerization of pyrrole on carbon nanotubes, that further boosts actuation by taking advantage of the peculiar properties of both materials in terms of maximum strain and conductivity;4 we investigated the influence of actuator thickness showing that the generated strain at high frequency is strongly enhanced when thickness is reduced. To overcome limitations set by bimorphs, we designed a novel actuator in which a metal spring, embedded in the solid electrolyte of a bimorph device, is used as a non-actuating counter plate resulting in a three electrode device capable of both linear and bending motion. Finally, we propose a way to model actuators performance in terms of purely material-dependent parameters instead of geometry-dependent ones.5