Toward At-Home and Wearable Monitoring of Female Hormones: Emerging Nanotechnologies and Clinical Prospects

Steroid hormones, especially progesterone (P4), estradiol (E2), and testosterone (T), are key bioactive regulators in various female physiological processes, including growth and development, ovulation, and the reproductive cycle, as well as metabolism and mental health. As lipophilic molecules produced in sex glands, these steroid female hormones can be transported through blood vessels into various body fluids such as saliva, sweat, and urine. However, the ultralow concentration of steroid hormones down to picomolar (pM) level necessitates great demands for ultrasensitive but low-cost analytic tools to implement accurate, point-of-care or even continuous monitoring in a user-friendly fashion. This review focuses on the latest advances in materials and nanotechnologies to allow the rapid detection of female hormones at the pM level or below and the potentials in at-home and wearable hormone monitoring. We specifically summarize the optical and electrochemical strategies in this category, particularly those affording low cost and portable signal readout for at-home use. Furthermore, emerging flexible/wearable innovations are highlighted, which allow the continuous hormone cycle tracking in a noninvasive manner. The potential of these techniques is discussed to address the need for real-time acquisition of the hormone fluctuation, facilitating health monitoring at home. Lastly, we provide a comprehensive introduction to the prospects of female hormone monitoring in clinical diagnosis and treatment, from the perspective of gynecology and reproductive medicine clinicians.