Self-Powered Electrochromic Readout of Potentiometric pH Electrodes

Area of Science:

• Electrochemistry
• Chemical Sensing
• Materials Science

Background:

• Traditional sensors often require external power sources, limiting their portability and application in remote settings.
• Developing self-powered sensing systems is crucial for advancing portable and autonomous analytical devices.
• Prussian blue (PB) films offer electrochromic properties suitable for optical sensing applications.

Purpose of the Study:

• To develop a self-powered absorbance-based colorimetric sensor array.
• To demonstrate the direct power transfer from an ion-selective electrode (ISE) to a potential-dependent Prussian blue (PB) film.
• To enable colorimetric detection without external power supplies.

Main Methods:

• A short-circuited cell configuration was used, where the ISE potential directly powered a PB film.
• The ISE potential, proportional to ion activity, controlled the PB film's color change.
• A model system utilized poly(vinyl-chloride)-based pH electrodes with varying internal filling solutions to tune the pH range.

Main Results:

• The self-powered sensor achieved a pH measuring range from 2 to 10.5.
• Sensor output was independent of solution ionic strength due to potentiometric driving force.
• Quantitative analysis was successful in complex samples like red wine, coffee, and beverages, with results correlating well to a reference pH electrode.
• The PB film demonstrated excellent reproducibility and a rapid response time of approximately 44 seconds.

Conclusions:

• A novel self-powered colorimetric sensor array was successfully developed and demonstrated.
• The system effectively utilizes ISE potential to drive an optical color change in PB films.
• This technology offers a promising platform for portable, power-independent chemical sensing in diverse real-world samples.