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Forensic Finger

Forensic Finger

Jacobs School engineers have developed a wearable sensor that can quickly detect gunpowder and explosives at a crime scene.

Researchers from Joseph Wang's lab in the NanoEngineering Department tested the device at a local firing range where it was accurate 75 percent of the time and delivered results in about four minutes. This "forensic finger" project is still at the proof-of-concept stage.

Doctoral student Amay Bandodkar and postdoctoral fellow Aoife O'Mahony are leading the effort to create forensic-finger sensors on the fingertips of latex gloves using proprietary screenprinting technology.

The glove's index finger, which investigators would use to swab for samples, is equipped with a screen-printed sensor made of silver chloride and carbon electrodes. The thumb is equipped with a solid-state ionogel, an ion-conducting liquid set inside a polymer matrix. Bring the thumb and index finger together and the two sensors combine to become an electrochemical cell. The powder in the collected sample reacts on the carbon electrode to reveal the electrochemical signatures characteristic of heavy metals found in gunpowder and signatures of electroactive components found in explosives. The sensor transmits the information to a portable electrochemical analyzer that displays the results. The device would be useful for a wide range of on-site crime scene investigations in various forensic and combat situations.

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