Repository logo

Capacitive touchscreen sensing - A measure of electrolyte conductivity

Accepted version



Change log


Henderson, CJ 
Hall, EAH 


Mobile technologies such as smartphones and tablets combine computational power with inbuilt sensors and networking capabilities, making them ideal measurement instruments. There is already a rich history of research and commercially manufactured accessories taking advantage of their sensing and data visualisation capabilities. However, to-date the touchscreen component has not yet been translated to the widely established fields of capacitance-based bio- and environmental sensing. Here, we demonstrate the concept of contactless conductivity sensing of fluid samples placed directly on top of a projected mutual capacitive touchscreen with the measurement of a variety of electrolytes, leveraging the touchscreen’s multi-touch capabilities. Electrolyte ions are particularly susceptible to the electric fringe field induced by capacitive touchscreens, and we report here a near-linear response to the ionic concentration of metal cations interesting for drinking water quality and soil health monitoring across a range of 0 to 500 µM (up to 100 µS). Simulation results are compared with experimental findings to reveal both the working principles and the key parameters that will be important for future sensing applications. This sensor demonstration is a starting point for broader exploration of the use of projected touchscreen sensing in mobile technologies and the creation of tools that are accessible to everyone, allowing rapid measurements and communication of data



Electrolyte, Touchscreen, Capacitive sensing, COMSOL, Water quality, Soil health

Journal Title

Sensors and Actuators, B: Chemical

Conference Name

Journal ISSN


Volume Title



Elsevier BV
Engineering and Physical Sciences Research Council (EP/L015889/1)
This research was supported by the UK Engineering and Physical Sciences Research Council (EPSRC) grant EP/L015889/1 for the EPSRC Centre for Doctoral Training in Sensor Technologies and Applications. We also thank MSolv Ltd. for supplying touchscreen device samples and in particular Phil Rumsby and Adam Brunton for technical support and fruitful discussions. We thank TouchNetix for providing readout hardware for the capacitance measurements. We thank Dr. Ljiljana Fruk and Christoph Franck from the Department of Chemical Engineering and Biotechnology of University of Cambridge for providing us with electrolyte testing solutions.