Textile-based wearable device for detection of date rape drugs in drinks

Abstract

In this article, a sensing element for detection of date rape drugs in drinks is presented. The element consists of a three-dimensional printed holder, in which two embroidered electrodes have been fixed, forming a capacitive structure. As the dielectric properties of the liquid between these electrodes’ changes, the capacitance and consequently the impedance are changed. For experimental purposes, diazepam, a model rape drug, sucrose, and sodium chloride, which are used as control ingredients, were dissolved in a 40% V/V alcoholic beverage, serving as solutions for testing and comparison. The selectivity, repeatability, and sensitivity of the proposed sensor were tested. The sensitivity of detection of 1 mg/ml of diazepam in drinks was 0.92628 Ωl/mg, sucrose was 0.94774 Ωl/mg and sodium chloride was 2.46867 Ωl/mg, at 1 MHz. Moreover, with the use of the Cole impedance model, the selectivity of the sensor in the detection of diazepam, through the Nyquist plot and parameter estimation, has been achieved. Sensor repeatability was calculated through the relative standard deviation with the result for 1 mg/ml of diazepam dissolved in alcohol on 1 MHz being 2.48, in terms of impedance modulus. The presented sensor platform can successfully detect drugs in drinks and can protect from many cases of such assaults in a real world.