Localization of Ion Concentration Gradients for Logic Operation

Abstract

Adjustment of the environmental acidity is a powerful method for fine-tuning the outcome of many chemical processes. Numerous strategies have been developed for the modification of pH in bulk as well as locally. Electrochemical and photochemical processes provide a powerful approach for on-demand generation of ion concentration gradients locally at solid-liquid interfaces. Spatially organized in individual way electrodes provide a particular pattern of proton distribution in solution. It opens perspectives to iontronics which is a bioinspired approach to signaling, information processing, and storing by spatial and temporal distribution of ions. We prove here that soft layers allow to control of ion mobility over the surface as well as processes of self-organization are closely related to change in entropy. In this work, we summarize the achievements and discuss perspectives of ion gradients in solution for information processing.

Shannon entropy associated with electrochemically generated ion concentration gradients

“…Self-organization processes are closely related to entropy change [6]. Entropy change usually relates to a change of thermodynamic parameters such as temperature and pressure or chemical parameters.…”

“…The diffusion of oxidation products is highly affected by the structure of the electrode surface [5,6]. Polyelectrolyte modified electrodes are of high interest [7,8].…”

Chemical Systems for Life Science

“…Therefore, pH-sensitive systems draw the most attention in developing smart materials and several ways to regulate pH in bulk as well as locally [96]. Proton coupled electron transfer is widely used for electrochemical generation of pH gradient [97]. Chemical and a biocompatible way to get pH gradient in solution may involve immobilized enzymesthat catalyze formation of an acid or acid-producing bacteria that are attached to a surface (Fig.…”

“…4d) [112], assembly triggering by light-pH coupling effect is still a challenge. The challenging prospects of synthetic cell construction are 1) ion feedback mechanism in synthetic capsules [96], in vivo biomolecule synthesis inside synthetic cell [113]; 2) localization of biochemical processes inside capsule [97], and 3) delayed assembly of biomolecules on the surface and inside capsules.…”

Photoelectrochemical photocurrent switching effect on a pristine anodized Ti/TiO2 system as a platform for chemical logic devices

“…17 Ion uxes consideration as information transducers in solution were proposed 18 and performing simple logic operations was demonstrated. 19 This phenomenon opens perspectives to biomimetic information processing and developing effective humanmachine interfaces. 20 Photoelectrodes using light and potential as inputs and yielding photocurrents are being considered as the basis for logic devices.…”