Making use of the sol-gel technique, an optical pH sensor was prepared, which was made from an organic carrier with four indictors including congo red, bromophenol blue, cresol red, and chlorophenol red, cross-linked by tetraethyl orthosilicate (TEOS) and cellulose acetate. The actual detection range of the optical pH sensor is 2.5–11.0. The optimal ratio of ethyl orthosilicate, absolute ethanol, deionized water, and hydrochloric acid in glue precursor of the sensor-sensitive membrane was explored. The orthogonal experiment was designed to optimize the dosage of cellulose acetate, N,N-dimethylformamide (DMF), indicator, hydrochloric acid, and precursor glue in preparing the sensor-sensitive membrane. The linearity, measurement accuracy, repeatability, stability, and response time of the prepared pH sensor were tested. The measurement results were analyzed using a support vector machine and linear regression. The experimental results show that the optical pH sensor has a measurement accuracy of up to 0.2 pH and better stability and repeatability than the traditional pH glass electrode.

In the color difference inspection system based on machine vision, two types of dyeing effects need to be evaluated quantitatively according to color measurement results: the color consistency – the color matching degree between the dyeing product and the target; and the color levelness – the color uniformity in different regions of the same dyeing product. The purpose of this paper is to develop the color consistency and levelness evaluation algorithms and a new evaluation model of dyed fabrics based on the Support Vector Machine (SVM). Firstly, the evaluation goals were quantitatively classified into five different levels according to ISO 105-A02:1993; secondly, six color difference-related features from two color spaces were defined as the evaluation indexes, among which several independent ones were chosen using the Principal Components Analysis method from the training data and test data to improve the speed of the evaluation while retaining the accuracy. Finally, the evaluation model was built by employing the SVM method and its parameters were optimized with the Genetic Algorithm. The SVM model was then used to evaluate the dyeing effects according to the measured color difference-related features. Experimental results show that compared with the traditional Naive Bayesian algorithm, the proposed evaluation algorithms and model in this paper can evaluate the color quality of dyed fabrics quickly and decisively, with prediction accuracy increasing by 9% and relative error reducing by 0.0985.

The solid-state pH electrode has the potential possibility to be used in many extreme situations with satisfactory accuracy and low cost. But its performance is affected by the solid electrolyte, preparation process, and the structure of the sensitive membrane, etc. In this work, the relationships between these factors and the characteristic of the prepared electrode were verified by controlling the preparation conditions with a variety of electrochemical methods. Firstly, the solid electrolyte poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) was electrochemically deposited on the screen-printed carbon electrode (SPCE) substrate by a potentiostatic method in an aqueous solution containing 0.01 M 3,4-ethylenedioxythiophene (EDOT) and 0.1 M polystyrene sulfonic (PSS) acid as the supporting electrolyte. The PEDOT films were then characterized by cyclic voltammetry (CV) in the 0.1 M NaNO3 aqueous solution in order to obtain the optimized polymerization potential and charges where the PEDOT film would have a higher redox capacitance. Finally, the pH electrode was prepared by coating the SPCE/PEDOT(PSS) with a plasticized polyvinyl chloride (PVC) membrane containing tridodecylamine as hydrogen ionophore manually, and experiments were carried out to study the effect of the usage of PVC per square millimeter on the response time and stability of the electrode to optimize the PVC film thickness. The potentiometric response of the pH electrode was studied in the buffer solutions with pH ranging from 5.00 to 10.81 by the open-circuit potential (OCP) method. Experimental results show that the sensitivity of the electrode is −55.7 ± 0.5 mV pH ⁻¹ ( r ² > 0.9980) at room temperature (24 ± 1 °C) with pH ranging from 2.00–10.50, approximating to the theoretical nernstian slope (−59.16 mV pH ⁻¹ ),and the response time was less than 10 s. Moreover, it has low impedance, high accuracy and potential stability as well as some other useful properties such as pressure and heat resistance, hydrofluoric acid resistance, and it is not as fragile as the glass electrode.