Factors Influencing the Long-Term Stability of Electronic Tongue and Application of Improved Drift Correction Methods

Abstract

<jats:p>Temperature, memory effect, and cross-contamination are suspected to contribute to drift in electronic tongue (e-tongue) sensors, therefore drift corrections are required. This paper aimed to assess the disturbing effects on the sensor signals during measurement with an Alpha Astree e-tongue and to develop drift correction techniques. Apple juice samples were measured at different temperatures. pH change of apple juice samples was measured to assess cross-contamination. Different sequential orders of model solutions and apple juice samples were applied to evaluate the memory effect. Model solutions corresponding to basic tastes and commercial apple juice samples were measured for six consecutive weeks to model drift of the sensor signals. Result showed that temperature, cross-contamination, and memory effect influenced the sensor signals. Three drift correction methods: additive drift correction based on all samples, additive drift correction based on reference samples, and multi sensor linear correction, were developed and compared to the component correction in literature through linear discriminant analysis (LDA). LDA analysis showed all the four methods were effective in reducing sensor drift in long-term measurements but the additive correction relative to the whole sample set gave the best results. The results could be explored for long-term measurements with the e-tongue.</jats:p>

Classification of Bee Pollen and Prediction of Sensory and Colorimetric Attributes—A Sensometric Fusion Approach by e-Nose, e-Tongue and NIR

“…For the e-tongue, a drift correction method called "additive correction relative to all samples" was applied on the data set to reduce the effect of ageing on sensor signals. The method was developed by Kovacs et al [64].…”

Sensory and Physicochemical Evaluation of Acacia and Linden Honey Adulterated with Sugar Syrup

“…PCA was used for the identification of outliers as an exploratory data evaluation method and for visualization of the main patterns and information of the multivariate sensor set. Before the analyses, in the case of electronic tongue results, a drift correction (additive correction relative to reference samples) was used for correcting the drift between different measurement days [ 35 ]. LDA classification models were built for the two honey types separately.…”

Historical Evolution and Food Control Achievements of Near Infrared Spectroscopy, Electronic Nose, and Electronic Tongue—Critical Overview

“…The sensor drift, engendered by such factors, has been a subject of a wide number of studies. With varying outcomes, the proposed solutions ranged from maintaining the cleanliness of the sensor membranes [ 17 ] to performing systematic calibrations and other mathematical corrections [ 18 ]. Analysis with NIR spectroscopy, on the other hand, can be dependent on reference methods, for calibration and validation purposes [ 19 ].…”

“…Besides these statistical techniques, the data provided by any of the discussed correlative analytical methods require special pretreatments based on their unique behavior, data structure, and issues of sensitivity that can result from numerous environmental conditions. In this regard, noise reduction algorithms [ 34 ], drift corrections [ 18 ], normalizations, sensor/spectra selection, and data dimension reduction can be applied before using it to build multivariate models for qualitative and quantitative evaluations [ 35 ].…”

“…Another way of enhancing the cross-selectivity of the sensors has been envisaged by Parra et al [ 212 ], who diversified the coating materials of the electrodes including chemo-sensitive polypyrrole, metallophthalocyanine, and perylene derivatives. Since drift is one of the major hindrances precluding the wider application of E-tongues, various drift correction methods have been developed, that could substantially improve the long-term applicability of potentiometric E-tongue sensors [ 18 ]. Other approaches and their demonstrated performances have been extensively reported by [ 213 ].…”