Fully-printed and silicon free self-powered electrochromic biosensors: Towards naked eye quantification

Electrochromic materials are becoming increasingly important in analytical devices and applications. Their opto-electronic properties make them particularly useful in the development of electronics-free, self-powered sensors. However, the mass manufacture of such devices is often limited by the need for transparent electrodes and liquid electrolyte systems. The self-powered biosensor presented here overcomes these limitations by means of a coplanar construction and a gel electrolyte. This configuration enables an effective separation between the sample and the electrochromic component, which allows the naked eye readout of the analyte concentration even if coloured or dark samples, such as blood, are used. This lack of contact between sample and electrochromic material also prevents the action of possible interferents on the electrochromic display, which is an additional advantage. Moreover, because the device is entirely screen-printed, its mass production is also feasible. The fabricated device features a glucose biosensor connected to a Prussian-Blue electrode, displaying a dynamic range between 2.5 mM-10 mM that makes it suitable for blood testing and diabetes screening.