Instantly identifying illicit drugs

A Taiwanese research collaboration has built a tiny biochip that can instantly identify illicit drugs such as cocaine and amphetamines in their natural powdered form.

The method involved simply depositing the powder to be identified into a small, rectangular glass-and-plastic biochip containing some electronic components. The powder settles into channels 20 microns deep. Inside the biochip, a small transmitter beams electromagnetic radiation in the terahertz (THz) range (in between the microwave and infrared), to which biomolecules are very sensitive. By recording how much radiation the powder absorbs over a range of frequencies, the researchers obtain distinctive chemical fingerprints of the molecules that make up the powder.

Using this method, the researchers, led by Chi-Kuang Sun from the National Taiwan University, were able to distinguish powders of cocaine (which absorbs a maximum of radiation at 0.8 THz) and amphetamine (1.03 THz) from powders of potato starch, flour, and lactose. Less than five seconds were required to complete each scan. In addition, the drug's distinctive THz signatures make them possible to detect even when mixed in with another ingredient such as flour.