Pressure-Sensitive Sampling Wands for Homeland Security Applications

This paper discusses the use of force sensing resistor (FSR) technology integrated into sampling wands used for homeland security applications. FSR-integrated wands can be used for the optimization of wipe sampling of surfaces to facilitate enhanced trace contraband collection. Collection efficiencies during wipe sampling are known to be dependent on the applied force, or pressure, used during sampling. Light-emitting diodes designed to switch from red to green at a defined force threshold of 7 N provide feedback to the operator during sampling. The goal of maintaining forces at or above the threshold was successfully demonstrated by testing with a volunteer population of 22. An additional benefit is the reduction in the variability of the force applied by each operator during sampling. Another focus area is the development of prototype sampling wands that fit in the palm of the hand and other wand modifications that increase the reliability of wipe sampling by registering the placement of the collected sample properly on the wipe. This paper also outlines how an array-based FSR can be used to visualize contact area and pressure during wipe sampling.