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“Traffic light” detector shows caffeine presence

19 Sep 2013

The "traffic light" detector signals the amount of caffeine in drinks

Prof Chang (right) and graduate student Mr Xu Wang with the caffeine detector kit
Caffeine is present in many drinks and solutions, even those not usually associated with the stimulant, such as medicines. With growing concern about the effects of excessive caffeine consumption on health, a caffeine-detecting invention by NUS scientists and their collaborators in Korea will help ease such worries.

Although different studies have shown both positive and negative health-related impact of caffeine, an overdose of the substance can lead to caffeine intoxication, giving rise to physical symptoms such as anxiety, irregular heartbeat and sleeplessness. Extreme cases can cause hallucinations, depression or even death.

Professor Chang Young-Tae from NUS and Professor Cho Yoon-Kyoung from Ulsan National Institute of Science and Technology (UNIST), Korea, headed the joint research group that developed a fluorescent caffeine detector and a detection kit that lights up when caffeine is present in various liquids.

Published in Scientific Reports recently, the study unveiled the new caffeine sensor found by the NUS group named Caffeine Orange. The aqueous fluorescence provides visual cue of the amount of caffeine in coffee or energy drinks. With the non-toxic caffeine detection kit using Caffeine Orange, different caffeine concentrations based on colour changes when irradiated with a laser pointer can be seen with the naked eye.

Prof Chang - who is from NUS’ Department of Chemistry and MedChem Programme of Life Sciences Institute - and his team demonstrated that Caffeine Orange produced a 250-fold spike in fluorescence upon caffeine activation. It also showed high selectivity responding to caffeine analogues that have similar chemical structures.

Separately, the UNIST team designed an automated system by integrating microfluidics technique to extract and measure caffeine. This allows the kit to be easily used for quick and sensitive detection.

Prof Chang said that the caffeine detection kit can be regarded as a “traffic-light caffeine amount designator”. The reddish orange hue serves as a stop sign for people who have low tolerance to caffeine, while yellow and green indicate a warning signal and safe zone respectively, he added.

Thus, the caffeine sensor and detection kit can enhance product safety during extensive consumption of caffeine. Due to its presence in domestic wastage, caffeine is an important indicator of natural water system pollution by domestic drain. The detection kit may thus be applied in the monitoring of water system safety.

The researchers have patented the caffeine-sensing technology and several companies have shown interest in applying it.