Significance of the science

Managing chronic conditions—such as heart disease, neurodegenerative disorders, and reproductive health—requires regular monitoring of key biomarkers like hormones and proteins. Today, this usually means clinic visits or sending samples to centralized labs, which is slow, costly, and inconvenient. Existing rapid tests often aren’t sensitive enough to detect very low biomarker levels, while advanced lab instruments are too bulky and expensive for everyday use.

To bridge this gap, we have developed a low-cost, lab-quality diagnostic platform that combines a new type of electrical enzyme test with paper-based fluidics and a handheld reader. Our first application detects estradiol, a hormone critical to women’s reproductive health, showing the potential for accurate, affordable, and accessible at-home monitoring.

Highlights

• Introduces a radical-mediated electrical enzyme assay (REEA) for highly sensitive biomarker detection

• Combines electronics and paper-based fluidics in a portable format

• Produces results in under 10 minutes

• Costs only $0.55 per test

• Detects estradiol at extremely low levels (146 fg/mL) with high precision in clinical samples

Summary

The diagnosis and prognosis of many conditions such as cardiovascular, neurodegenerative, and reproductive disorders often require repeat monitoring of small molecules, proteins, hormones, or other biomarkers with a high analytical sensitivity. We developed a radical-mediated electrical enzyme assay (REEA) in a paper-based fluidic cartridge ($0.55/test) with a handheld reader utilizing field-effect transistors to measure estradiol (E2), a key hormone in reproductive care. The system demonstrated a detection limit of 146 fg/mL, a coefficient of variation below 9.2%, and an accuracy of 0.963 across 19–4,551 pg/mL in clinical plasma samples, with results delivered in under 10 min. The REEA method presents a high-sensitivity electrochemical transducing system and can be used to detect other high-sensitivity biomarkers, including cardiac troponin and tau proteins associated with Alzheimer’s disease.

Read more (open access): https://www.cell.com/device/fulltext/S2666-9986(25)00120-6?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS2666998625001206%3Fshowall%3Dtrue