Recent advances in ion sensing with conducting polymers

Abstract

Ions are present throughout our environment-from biological systems to agriculture and beyond. Many important processes and mechanisms are driven by their presence and their relative concentration. In order to study, understand and/or control these, it is important to know what ions are present and in what concentration-highlighting the importance of ion sensing. Materials that show specific ion interaction with a commensurate change in measurable properties are the key components of ion sensing. One such type are conducting polymers. Conducting polymers are referred to as 'active' because they show observable changes in their electrical and optical (and other) properties in response to changing levels of doping with ions. For example, p-type conducting polymers such as poly(3,4ethylenedioxythiophene) and polypyrrole, can transition from semi-conducting to metallic in response to increasing levels of anions inserted into their structure. Under certain circumstances, conducting polymers also interact with cations-showing their utility in sensing. Herein, recent advances in conducting polymers will be reviewed in the context of sensing ions. The main scope of this review is to critically evaluate our current understanding of ion interactions with conducting polymers and explore how these novel materials can contribute to improving our ion-sensing capabilities.

Oxygenation of conducting polymers facilitated by structure‐breaking anions

“…For example, in aqueous environments the presence of different analytes can lead to significant changes in the CPs optical, electrical, thermal, and/or mechanical properties to name but a few. 1 Such behavior forms the motivation to utilize CPs as the active material within a range of sensor devices. CPs are researched as the active material in the sensing of ions, 1,2 gases, 3 and biological material, 4 to name a few.…”

“…The ability to sense arises from the process of inserting/removing charged atoms/ molecules and the resultant change in CP properties that can be measured. 1 Not only do the charge carriers within the CP provide it with electrical and thermal conduction, they also act as potential reactive sites. For example, Hojati-Talemi et al demonstrated that amine-based molecules readily reacted with the positive charges in PEDOT.…”

Poly(1,5-Diaminonaphthalene)-Modified Screen-Printed Device for Electrochemical Lead Ion Sensing

“…The conducting polymer's interesting features are its superior electrical conductivity, high specific surface area, good adhesion, and enhanced signal responses for target metal ions [15]. A large number of reports have shown that people used polymer composite electrodes for detection of Pb 2+ such as polyaniline/carbon nanotubes [16], poly(vinylsulfonate)doped polyaniline [17], p-phenylenediamine [18], poly(3,4-ethylenedioxythiophene) [19], polypyrrole/carbon nanofibers [20], PEDOT/black TiO 2 [21], and polydiaminonaphthalene [22,23].…”

A Fibre-Optic Platform for Sensing Nitrate Using Conducting Polymers

“…Ions play an important role in many biological and engineering processes. Their concentration in aqueous solution is important for practical applications such as defining the quality of drinking water, the treatment of wastewater and production of food [ 1 , 2 ]. Nitrate is an ion of interest in several of these scenarios; for example, it plays a key role in the nitrogen cycle in agriculture [ 3 ], removing the hazardous contaminants from the aquatic environment [ 4 , 5 , 6 ], and in measuring nitrate oxide in blood [ 7 ].…”