Potentiometric performance of flexible pH sensor based on polyaniline nanofiber arrays

Hong Jun Park,Jo Hee Yoon,Bong Gill Choi,Kyoung G Lee

doi:10.1186/s40580-019-0179-0

Hong Jun Park, Jo Hee Yoon + Show 2 more

Open Access

https://doi.org/10.1186/s40580-019-0179-0

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Abstract

We report potentiometric performance of a polyaniline nanofiber array-based pH sensor fabricated by combining a dilute chemical polymerization and low-cost and simple screen printing process. The pH sensor had a two-electrode configuration consisting of polyaniline nanofiber array sensing electrode and Ag/AgCl reference electrode. Measurement of electromotive force between sensing and reference electrodes provided various electrochemical properties of pH sensors. The pH sensor show excellent sensor performances of sensitivity of 62.4 mV/pH, repeatability of 97.9% retention, response time of 12.8 s, and durability of 3.0 mV/h. The pH sensor could also measure pH changes as the milk is spoiled, which is similar to those of a commercial pH meter. The pH sensors were highly flexible, and thus can measure the fruit decay on the curved surface of an apple. This flexible and miniature pH sensor opens new opportunities for monitoring of water, product process, human health, and chemical (or bio) reactions even using small volumes of samples.

Highlights

Detecting pH value, commonly measuring acidity and alkalinity in a given solution, can be used as an indicator for assessment of environment, biochemical, and biological processes [1−4]
3 Conclusions We developed a highly flexible pH sensor based on a screen printing process using a carbon and Ag/AgCl pastes
As a flexible sensing electrode material, polyaniline nanofiber arrays were deposited on carbon-working electrode by a dilute chemical polymerization

Summary

Introduction

Detecting pH value, commonly measuring acidity and alkalinity in a given solution, can be used as an indicator for assessment of environment, biochemical, and biological processes [1−4]. The potentiometric pH sensor measures the difference in electromotive force (EMF) between a pH sensing electrode and a reference electrode. A screen printing is based on a mask (screen) to transfer pastes onto a substrate, excluding the areas made impermeable to the paste by a blocking stencil [21,22,23]. This is a scalable and low-cost process and is suitable for microsized materials and devices. The pH sensor is based on potentiometric technique, measuring EMF between two electrodes. The flexibility of pH sensor enabled to measure pH level on the curved apple surface

Results and discussion

Conclusions

Experimental

Preparation of electrical electrodes using screen printing process