Influence of Thickness of Screen Printed Carbon Electrodes on Electrochemical Sensing

Abstract

Screen printing is one of the widely used methods for printed sensors and electronics. The performance of these devices could vary with the printing parameters such as thickness of the printed layer, the squeeze length and pressure applied for printing etc. Whilst sensor design and the ink used for the printing of sensitive layers have been studied previously, the vital printing parameters has not attracted much attention. This paper reports the influence of thickness of printed sensor on their electrochemical sensing property. Carbon ink is used to print sensors with three-electrode geometry and their working electrode is modified with MoS2 to study the detection of ascorbic acid. The thicknesses of the sensitive layers varied from ~4 m to 120 m as the number of printed layers of ink increased from 1 to 5, 10 and 20. The cyclic voltammetry, differential pulse voltammetry and impedance spectroscopy are used to investigate the electrochemical performance. It was noted that the peak current indicating the oxidation of ascorbic acid at 0.04 V, increased with the increase in the thickness of electrode or the number of printed layers. The higher current values and lower series resistance was measured for layers 10 and 20, indicating the ideal printed thickness of sensors for low power operation and easy interfacing with read out electronics.

Adaptive Fabrication of Electrochemical Chips with a Paste-Dispensing 3D Printer

“…For example, commercially available Zensor and PalmSens screen-printed electrodes have thicknesses of 10 µm and 350-380 µm, respectively [51,52]. Research indicates that electrodes with lower thicknesses exhibit low current values and high resistance, while higher current values are recorded for electrode thicknesses starting from 60 µm onwards [53]. Thus, the thicknesses of our printed electrodes were within a satisfactory range for sensing, although they were not very thick.…”

“…As the electrodes are printed in a raster pattern using a 3D printer, imperfect build plate leveling could cause the raster pattern to be printed with varying roughness. Different working electrode thicknesses could result in varying electrode resistances, and their surface roughness could affect the electroactivity of the analytes on the working electrode [11,53]. As a result, the signal received could vary from chip to chip.…”