Implantable bioelectronic devices for photoelectrochemical and electrochemical modulation of cells and tissues

Electroceuticals are bioelectronic devices that provide or modulate electrical or electrochemical signals to regulate physiological functions. In particular, devices designed for energy conversion are capable of transforming electrical energy into alternative forms of energy, such as heat or light, or vice versa, thereby enabling the photoelectrochemical and electrochemical modulation of biological systems, for example, to control muscle movement or cardiac rhythm. Such energy conversion approaches offer remote control and enhanced precision, surpassing the limitations of direct tissue and cell stimulation with traditional electroceutical devices, such as pacemakers, including mechanical mismatch at interfaces and wired communication. In this Review, we explore the fundamental principles of photoelectrochemical and electrochemical modulation of cells and tissues, emphasizing behaviour under physiological conditions. We then examine the development and application of implantable bioelectronics that use photoelectrochemical and electrochemical processes for modulation. Finally, we discuss future directions for energy conversion devices in implantable electroceuticals.