CLOSED-LOOP AND ON-DEMAND CONTRACEPTIVE TECHNOLOGIES: A REVIEW OF SMART DEVICES FOR FERTILITY CONTROL IN MEN AND WOMEN

Contraceptive technology is shifting from passive, user-dependent methods toward active, responsive systems built on advances in materials science, microelectronics, and formulation engineering. This review summarizes emerging smart contraceptive technologies for men and women, organized by mechanism of responsiveness: (1) programmable electronic implants enabling wireless, on-demand or scheduled drug release; (2) self-assembling injectable microcrystals that form a monolithic implant in situ; (3) microneedle-based systems for painless, sustained transdermal delivery; (4) on-demand, user-controlled vaginal pH regulators; and (5) ultrasound-responsive hydrogels for reversible male contraception. For each category, we describe the mechanism of action, developmental stage, available efficacy and safety data, and user-acceptability considerations, with attention to technologies that reduce dependence on surgical insertion/removal and healthcare-provider access, and that expand options for men. We conclude by identifying gaps and future directions, including biosensor-integrated closed-loop fertility monitoring and multipurpose prevention technologies combining contraception with STI prophylaxis.