Metamaterial inspired radio frequency-based touchpad sensor system

Abstract

This paper proposes a metamaterial inspired radio frequency touchpad sensor system based on two split ring resonators (SRRs) realized on a Rogers/Duroid 5870 with 2.33 dielectric constant = 2.33, loss tangent = 0.0012, and thickness = 0.8 mm. The touchpad consists of two SRRs resonating at f1 = 2.74 GHz and f2 = 3.86 GHz. When a finger is placed on SRR 1, f1 changes from 2.74 to 2.57 GHz due to electromagnetic coupling between the SRR and the finger, and similarly, f2 changes from 3.86 to 3.76 GHz. The proposed touchpad system can detect a finger wearing a glove, in contrast to capacitive touchpads utilized in contemporary smart phones. We demonstrated 56- and 49-MHz frequency shifts for f1 and f2 , respectively, with 1.66-mm total thickness (0.69-mm-thick photo paper and 0.97-mm-thick glass slide). © 1963-2012 IEEE.