The colorimetric sensor demonstrates real-world application on human skin. The BHEI-embedded agarose gel within the tattoo-like sticker undergoes a visible color change from its baseline state to red upon exposure to γ-hydroxybutyrate (GHB). It provides detection within 1 second at concentrations as low as 0.01 mg/mL. Credit: Adapted from ACS Sensors 2025, DOI: 10.1021/acssensors.4c03737
A new wearable sensor, disguised as a temporary tattoo, detects trace amounts of gamma-hydroxybutyrate (GHB) in beverages within one second, using a colorimetric chemical receptor embedded in an agarose gel. Detailed in a July 23 ACS Sensors study, the sticker uses the silicone-based polymer polydimethylsiloxane film and poly(vinyl alcohol) for durability and adhesion, offering a low-cost, scalable platform for real-time chemical detection. Tested across whiskey, vodka, beer, soju and coffee, the technology could pave the way for broader applications in environmental and health monitoring.
A novel wearable chemical sensor
The authors hail the sensor’s three-layer architecture as an advance in wearable chemical sensor design, although other researchers have explored temporary tattoo-like sensors for years. At its core, the BHEI (2-(3-bromo-4-hydroxystyryl)-3-ethylbenzothiazol-3-ium iodide) chemical receptor embedded in the agarose gel matrix builds on previous work by the same Korean research team, which demonstrated similar colorimetric detection using hydrogel-based self-protection products. The agarose gel serves multiple functions beyond simple encapsulation. Its porous structure acts as a molecular sieve, filtering out large biomolecules while allowing small target molecules to diffuse rapidly to the receptor sites. This selective permeability, combined with the gel’s ability to maintain BHEI stability over 30 days post-detection, addresses core challenges in developing reagentless colorimetric sensors. The manufacturing process employs a simple mold-based approach that could enable mass production at costs significantly lower than current electrochemical sensing technologies.
Potential applications are diverse
While the immediate application targets drink safety, the underlying technology platform opens doors to numerous sensing applications. The Korea Institute of Science and Technology (KIST), where co-corresponding author Oh Seok Kwon leads the Sensor System Research Center, has focused on developing next-generation chemical sensors for environmental and health monitoring. The tattoo sticker’s design principles, which combine conformable substrates, stable chemical receptors and visual readouts, align with broader trends in electronic tattoo development for applications ranging from sweat analysis to neural interfaces. Similar agarose-based sensing platforms have shown promise for detecting hydrogen peroxide, glucose and other biomarkers, suggesting this technology could be adapted for continuous health monitoring or industrial process control.
The research team’s funding from the National Research Foundation of Korea and the Ministry of Food and Drug Safety underscores governmental interest in translating such innovations into practical safety solutions.
