Soft electronics based on particle engulfment printing

Soft polymers programmed with functional particles can be used to create intrinsically stretchable electronics. However, current approaches to fabricating such materials require that the particles be first colloidally dispersed in a liquid monomer or polymer solution that have limited material compatibilities and necessitate precise control over the associated fluid mechanics during the printing process. Here we report the direct incorporation of functional particles in soft polymers using particle engulfment, a process in which particles are spontaneously subsumed by the polymer matrix via surface energy. The engulfment phenomenon occurs when the characteristic size of the particles is much smaller than the elastocapillary length of the polymer matrix, resulting in an energetically stable configuration where functional particles become deeply embedded into the polymer. We use the approach to fabricate multilayered, multimaterial and elastic devices with wireless sensing, communication and power transfer capabilities.