Focusing the intervention of paper-based microfluidic devices for the forensic investigative purposes

It is a well-established fact that legally sound evidences are required to prove or disprove any criminal activity. When a particular activity occurs, it leaves a trace out of mutual contact and failure to detect that trace proves the activity did not occur. To enhance the capabilities of the justice system in evaluating evidence, researchers are continuously engaged in the development of novel analytical techniques which provide scientific methodologies for effectively assessing and interpreting the evidence associated with criminal activities. Among the several devices available, paper-based microanalytical devices (μPADs) have attracted the interest of forensic scientists/experts in recent years. These devices are designed with microchannels to which dedicated reagents are added for promoting selective reactions. As a result, they offer a practical and convenient solution for on-site detection of physical evidence, providing ready-to-use capabilities for forensic investigations. This does not only help the investigators in collection of legally sound evidences but also open avenues in apprehending the potential offender who might be present in the scene by detecting the traces. μPADs are inexpensive, simpler to operate, require less chemical consumption, portable, and provides results visible to naked eye. Furthermore, with the aid of digital scoring of color intensity, semi-quantitative results can be generated. This review explains current state of applications and operating chemistry of µPADs involved in analysis of evidences of forensic interest such as explosives, gunshot residue, drugs of abuse, pesticides, body fluids, and estimation of time since death. Furthermore, the research gaps in the domain and viability of future trends for the application of µPADs in forensic science are also presented.