Temporary pacemakers are essential for the care of patients with short-lived bradycardia in post-operative and other settings1–4. Conventional devices require invasive open-heart surgery or less invasive endovascular surgery, both of which are challenging for paediatric and adult patients5–8. Other complications9–11 include risks of infections, lacerations and perforations of the myocardium, and of displacements of external power supplies and control systems. Here we introduce a millimetre-scale bioresorbable optoelectronic system with an onboard power supply and a wireless, optical control mechanism with generalized capabilities in electrotherapy and specific application opportunities in temporary cardiac pacing. The extremely small sizes of these devices enable minimally invasive implantation, including percutaneous injection and endovascular delivery. Experimental studies demonstrate effective pacing in mouse, rat, porcine, canine and human cardiac models at both single-site and multi-site locations. Pairing with a skin-interfaced wireless device allows autonomous, closed-loop operation upon detection of arrhythmias. Further work illustrates opportunities in combining these miniaturized devices with other medical implants, with an example of arrays of pacemakers for individual or collective use on the frames of transcatheter aortic valve replacement systems, to provide unique solutions that address risks for atrioventricular block following surgeries. This base technology can be readily adapted for a broad range of additional applications in electrotherapy, such as nerve and bone regeneration, wound therapy and pain management.
