The ability to control the movement of charged species in the circuitry of living beings and machines is essential for complex signal processing, computation, and, ultimately, higher functionality. We describe a class of photo-ion generators (PIGs) based on non-ionic photoacids that can create large (> 1000x) irreversible changes in ionic conductivity under illumination, depending on the PIG species, concentration, and solvent. Incorporation of PIGs into elastomers by simple swelling methods yields soft (60 kPa ≤ E ≤ 10 MPa), stretchable, photo-ionic gels (PIGels). The resolution of photo-patterned conductivity in PIGels is less than 1 cm and demonstrates stability over several days, suggesting utility in engineered devices. Leveraging the photo-responsive properties of these materials, we demonstrate high-sensitivity mechanical sensors via conductance changes (∆ G / G 0 /σ = 20 MPa -1 ) and photo-writable, soft circuitry.
Liu et al. (Sat,) studied this question.