10 February 2021

Wearable sensor to detect prohibited substances in sweat developed

A wearable sensor that can detect prohibited substances in sweat via nano materials technology has been developed by researchers in the Republic of Korea, reports Medical & Life Science News. It is understood the optical signal of prohibited substances is enhanced using Raman scattering technology capable of enhancing the Raman signal of chemical substances by 1,010 times and more. This was necessary because only a relatively small amount of substances are discharged though sweat. As the Raman scattering signal is specific to the actual molecules involved, substance identification is possible.

It is understood that the amplified optical signal of prohibited substances in sweat is detected by a flexible, body worn material in a ‘sweat patch’ developed by researchers. The silkworm cocoon was utilised to develop the Surface-Enhanced Raman Scattering (SERS) sensor developed by researchers to detect the amplified Raman signal of chemical substances. A silk fibroin solution was used to develop a 160 nanometer thick film (0.00016 of a millimetre). This was coated with 250 nanometers thick silver nanowire and transferred to the ‘sweat patch’. 

This can be attached to the skin for a certain period of time and irradiated with light for testing. This takes approximately one minute, and is therefore much faster, plus uses less equipment and requires less space than current mass spectrometry techniques utilised by anti-doping Laboratories.

In similar fashion to Dried Blood Spot (DBS) testing, the new technology is not expected to fully replace the urine and blood tests traditionally used to detect prohibited substances in sport. However, like DBS, it is likely to enable anti-doping organisations (ADOs) to become more flexible in their approach by refining their testing programmes, and may enable them to reduce costs.

The current reliance on ‘wet’ samples places refrigeration and storage requirements on ADOs. WADA’s Sample Collection Guidelines specify that blood samples must arrive at the Laboratory within 72 hours (less, for some forms of analysis), must remain refrigerated throughout the process and not be allowed to freeze.

There are 30 accredited Laboratories listed on WADA’s internet site. Four are currently suspended, and – perhaps amazingly – only two had advised WADA that sample analysis may be disrupted due to Covid-19 by December last year. As the Bankgok and New Delhi Laboratories are currently suspended, any Southeast Asian ADO must ship blood samples to Beijing, Doha, Seoul or Tokyo. There is only one accredited Laboratory in Africa (South Africa).

If substances can be detected through use of either DBS or sweat analysis, then that may remove the need for Laboratory analysis of all samples, which could make anti-doping simpler, cheaper, and more effective. Analysis of figures produced by the World Anti-Doping Agency (WADA) in 2017 and 2018 reveal that approximately 0.6% of anti-doping tests result in an anti-doping rule violation (ADRV) against an athlete.

The research was supported by the Fundamental Research Program of the Korea Institute of Materials Science (KIMS) and was funded by the Ministry of Science and ICT. A scientific article fully explaining the development of the technology was published in ACS Applied Materials and Interfaces, and materials supporting the research can be freely downloaded. 

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