Research Highlight

Sanitary napkins that diagnose urinary infections by changing colour

doi:10.1038/nindia.2021.76 Published online 22 May 2021

Sanitary pad with thread-based detection showing pink patches for C. albicans.

© Prabhu, A. et al.

Researchers have developed colour-changing threads that turn bright pink in the presence of the yeast Candida albicans, which can cause painful urinary tract infections (UTIs)1

When embedded in tampons or sanitary napkins, they allow women to quickly and discreetly self-diagnose UTIs, that affect about 75% of women at least once in their lifetime.  

Many women throughout the world – either due to lack of access to basic healthcare facilities or societal taboos – stop seeking a doctor’s care. Naresh Kumar Mani's team at the Manipal Institute of Technology and collaborators from Kasturba Medical College, Manipal and the Indian Institute of Technology, Kharagpur, developed an inexpensive method that could be integrated into menstrual hygiene products. They coated ordinary multifilament cotton threads of sanitary napkins and pads with a molecule called L-proline β-naphthylamide (PRO) — the substrate for an enzyme secreted by C. albicans.

The portions of the pad containing PRO changed to a bright pink whenever these modified threads came into contact with C. albicans, signaling the presence of the pathogen. 

The threads detect infection within 10 minutes compared to a 24 to 72 hours diagnostic time for conventional tests. The test costs between 16 to 20 rupees (22 to 28 cents) per napkin or tampon. The method has a long shelf life making it a discreet detection device for self-testing multiple diseases that are considered taboo in certain societies, the researchers say.

It could easily be adapted to simultaneously detect other pathogens, such as bacteria that cause UTIs. Mani says to make the products market worthy, the team will need to further validate these results with clinical samples and increase the sensitivity of the tests.


1. Prabhu, A. et al. Knitting thread devices: Detecting Candida albicans using napkins and tampons. ACS Omega 6, 12667–12675 (2021) doi: 10.1021/acsomega.1c00806