Universidade do Minho,
Keywords: piezoresistive, sensor, environment-friendly, polymer composites
Summary:Smart materials are being increasingly implemented as sensors and actuators in a variety of products, ranging from automotive components and medical devices. Force and deformation sensors are among the most required sensors and are often based on the piezoresistive effect. Traditional piezoresistive sensors based on semiconductors present limited mechanical properties, difficulty to be integrated into material structures and sensitivity to environmental conditions. In the last years, it has been an increasing interest in printed electronics, being many of those efforts based on the development of polymer based materials . The growing demands of facile, low-cost, and scalable printable technologies, lead to the development of polymer based high-strain sensors . In this scope, one of the main scientific and technological issues, together with improving sensing capabilities and processability, is the removal of toxic solvents often used for the development of these types of materials, in order to improve safety, environmental and health issues . This work reports on the development of printable piezoresistive composites based on thermoplastic elastomer styrene-ethylene/butylene-styrene (SEBS)  and poly(vinyl alcohol) (PVA) as polymer matrix loaded with multi-walled carbon nanotubes (MWCNT) as nanofillers (Figure 1). The piezoresistive polymers can be formulated by green strategies, replacing the traditionally toxic solvent by greener solvents and water, leading to environmentally friendly materials and processes. Piezoresistive materials and sensors, applicable by screen and/or spray printing were developed with suitable piezoresistive response up to 80% deformation with a piezoresistive sensibility near 3, depending on the applied strain and filler content. Some applications based on these materials will be also presented.