Mickle and colleagues used a closed-loop wireless system with a strain gauge wrapped around the bladder of freely moving rats.1 The strain gauge measures changes in resistance during bladder filling and emptying. When the bladder becomes overactive, a signal is sent to activate a small microscale inorganic light-emitting diode (μ-ILED), which, in turn, activates a light-sensitive archaeal protein, an opsin, to selectively reduce neural activity. This action delivers a corrective signal, thereby restoring normal bladder function.