Ho Sang Jung
Original source: Materials Today
Researchers from the Korea Institute of Materials Science have produced a quick and reliable wearable sensor able to provide on-site drug detection. Their optical sensor can detect narcotics in sweat through the use of nanomaterial technology to amplify the optical signal of illegal drugs to their flexible and wearable material.
Standard drug testing involves a complicated approach to extracting suspected drug components from biologic specimens such as blood, hair and urine. These are assessed by gas or liquid chromatography-mass spectrometry, which requires much time and needs space for the instrument and skilled technicians. There are more rapid kits that detect drugs in urine, but they only detect a single component in a single test and have low sensitivity.
Anti-doping testing of athletes usually avoids blood testing because of the possible impact on performance, while urine testing can also violate human rights as the tester has to witness the process. However, in this study, reported in ACS Applied Materials and Interfaces [Koh et al. ACS Appl. Mater. Interfaces (2021) DOI: 10.1021/acsami.0c18892], a sweat patch is attached to the skin and then irradiated with light for testing, allowing for highly sensitive drug detectionthat takes just a minute with no further processes required.
As sweat is being tested, the concept is not invasive and relatively free from issues with human rights, as well as being cheap to fabricate. As team leader Ho Sang Jung points out, “The developed technology would overcome the technological limitations on identifying drug and prohibited substance use and enable drug detection without invasive and ethical problems”.
Despite sweat containing a range of drugs present in the bloodstream, only small amounts of substances are discharged in sweat, so very sensitive sensor technology was key. The sensor utilizes a sweat-sensing layer as an interface with human skin, a surface-enhanced Raman scattering (SERS) active layer and a dermal protecting layer to avoid damage and contamination. With the Raman scattering signal including the specific signal of molecules, it is possible to identify substances regardless of which drug is discharged.
On testing a silkworm cocoon protein, a natural protein was extracted to make a 160 nanometer (nm) thick film, which was coated with 250 nanometers (nm) thick silver nanowire and transferred to a medical patch that can be attached to skin. On the patch absorbing sweat, the drug substance penetrates the wearable sensor and reaches the silver nanowire. By irradiating the Raman laser on the patch, the drug can be detected in real time without the need to take off the sensor.