Portable detection system for identifying unknown liquid drugs

Detecting and identifying drugs at an incident scene is crucial for swift and accurate investigations. Existing drug detectors primarily analyze purified drugs by capturing particle or vapor samples, and these devices are often bulky, expensive, and inconvenient for field use. In this study, we present a portable detection system using a multichannel surface acoustic wave (SAW) sensor for identifying unknown liquid drugs. This sensor, based on Love-wave technology operating at 318 MHz, enhances sensitivity and enables detection through an immunoassay method. Each sensor channel was functionalized with a drug conjugated to bovine serum albumin (BSA). To detect and identify an unknown drug, the unknown sample was mixed with a multi-antibody (multi-Ab) solution and injected into the sensor. Unbound antibodies adhered to the corresponding drug-BSA complex, resulting in a frequency shift due to the mass loading effect. This rapid binding process produced results within 1 min. The portable system integrates a custom-made frequency analyzer and detection module, forming a handheld device weighing less than 250g, suitable for real-time field analysis. The portable system successfully detected nine drug types, including methamphetamine (MA), morphine, cocaine, ketamine, methylenedioxy pyrovalerone (MDPV), fentanyl, heroin, zolpidem, and methcathinone. This innovative technology offers a cost-effective, portable solution for on-site drug identification, significantly improving detection speed, selectivity, and sensitivity to enhance investigative efficiency.