Explosive detection at your fingertips
- Published: Aug 23, 2013
- Author: Jon Evans
- Channels: Detectors
Forget lab-on-a-chip, US nanoengineers have now developed lab-on-a-finger, which they have used to detect explosive and gunshot residues.
Termed a Forensic Finger, this lab-on-a-finger device consists of two plastic finger coverings worn on the index finger and thumb. A system of three electrodes for conducting voltammetry, in which analytes are detected by the current they generate when oxidizing or reduced at a working electrode, are printed onto the index finger covering. Then a small amount of electrolyte gel produced from an ionic liquid is placed on the thumb covering.
The idea is for a forensic investigator wearing these coverings to wipe their index finger along a surface such as a wall or floor in order to pick up any gunshot or explosive residue that might be present. Then they simply need to press their index finger and thumb together, forming an electrochemical cell consisting of the electrodes and electrolyte gel. This causes any gunshot or explosive residues picked up on the index finger to undergo redox reactions, producing a current that can be detected by a portable electrochemical analyzer.
Testing the Forensic Finger system in the laboratory, Joseph Wang and his colleagues at the University of California, San Diego, found that residue from gunshots and the explosive 2,4-dinitrotoluene (DNT) generated characteristic current changes. As reported in Analyst, they then took the system to a local firing range and showed that it could detect gunshot residues in this real-world setting in just four minutes.
To make the whole Forensic Finger system even more convenient and unobtrusive, Wang is now looking to incorporate the electrochemical analyser into a wristwatch or ring, and send the results wirelessly to a smartphone.