Fig. 4From: Disposable screen printed sensor for the electrochemical detection of delta-9-tetrahydrocannabinol in undiluted salivaScreen printed electrode (a) without and (b) with overlayer applied. The sensor comprised the ovalular carbon working electrode (3.2 mm length, 1.2 mm width) and outer concentric Ag/AgCl counter/reference electrodeBack to article page