Screen Printed Alizarin-Based Carbon Electrodes: Monitoring pH in Unbuffered Media

An alizarin based voltammetric pH sensor is introduced. This device is fabricated by screen printing the alizarin, which is a pH-sensitive redox compound, mixed with carbon ink onto the carbon aluminum (aluminum foil coated with carbon paste). This electrode shows a Nernst response to both the buffered and unbuffered media, with a potential shift by 55.8 mV/pH unit and a working range up to pH 10. This approach suggests a disposable, reproducible, low-cost method for pH sensing with the possibility of miniaturization. A further study of this type of sensor coated with nafion reveals a possible method to expand the working range and improve the stability.