Gone in 60 seconds: illegal drug use detected by wearable nanomaterial patch

The technology can trace the optical signal of narcotics using a flexible, body-worn material that enables fast and highly sensitive drug detection.

The sweat patch is attached to the skin for a certain period of time and then irradiated with light for testing in a process that only takes around one minute.

Traditional drug detection processes require a complex method of extracting suspected drug components from biologic specimens - including hair, blood and urine - and then analysing drugs through gas or liquid chromatography-mass spectrometry.

Although rapid kits can detect drugs in urine, they only detect a single component in a single test and have low sensitivity.

The researchers focused on sweat, which is non-invasive, unlike urine tests which can require a skilled technician to observe the process. Only a small amount of substances are discharged in sweat, so a highly sensitive sensor technology had to be developed for better detection.

The team’s sensing utilised the surface-enhanced 'Raman scattering technology', which is capable of enhancing the Raman signal of chemical substances by more than a thousand times.

As the Raman scattering signal includes the specific signal of molecules, intuitive substance identification is possible no matter what drug is discharged. The researchers used a natural protein, extracted from a silkworm cocoon, to make a 160nm-thick film to use as the sensor.

The film was coated with 250nm thick silver nanowire and transferred to the medical patch that can be attached to the skin.

Once the patch absorbs the sweat, the drug substance in the sweat 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 removing the sensor.

This technology can help address social problems such as drug distribution and abuse in clubs and other social settings, as well as detecting prohibited substances taken by athletes.

The team believes their patches could cost less than 50p (GBP) each.

“As seen in recent drug-related crimes, Korea is no longer a drug-free country. The developed technology would overcome the technological limitations on identifying drug and prohibited substance use and enable drug detection without invasive and ethical problems,” said lead researcher Dr Ho Sang Jung.