Influence of the Flow Rate in an Automated Microfluidic Electronic Tongue Tested for Sucralose Differentiation

Abstract

Incorporating electronic tongues into microfluidic devices brings benefits as dealing with small amounts of sample/discharge. Nonetheless, such measurements may be time-consuming in some applications once they require several operational steps. Here, we designed four collinear electrodes on a single printed circuit board, further comprised inside a straight microchannel, culminating in a robust e-tongue device for faster data acquisition. An analog multiplexing circuit automated the signal’s routing from each of the four sensing units to an impedance analyzer. Both instruments and a syringe pump are controlled by dedicated software. The automated e-tongue was tested with four Brazilian brands of liquid sucralose-based sweeteners under 20 different flow rates, aiming to systematically evaluate the influence of the flow rate in the discrimination among sweet tastes sold as the same food product. All four brands were successfully distinguished using principal component analysis of the raw data, and despite the nearly identical sucralose-based taste in all samples, all brands’ significant distinction is attributed to small differences in the ingredients and manufacturing processes to deliver the final food product. The increasing flow rate improves the analyte’s discrimination, as the silhouette coefficient reaches a plateau at ~3 mL/h. We used an equivalent circuit model to evaluate the raw data, finding a decrease in the double-layer capacitance proportional to improvements in the samples’ discrimination. In other words, the flow rate increase mitigates the formation of the double-layer, resulting in faster stabilization and better repeatability in the sensor response.

Self-Healing E-tongue

“…The potential usage of these LbL composites in sensing applications was evaluated through a proof-of-principle impedimetric electronic tongue (e-tongue). The device was fabricated similarly to those previously described by the authors . The e-tongue device analyzed electrolyte and nonelectrolyte liquids covering the basic tastes relevant for human gustatory perception (sweet, salty, sour, bitter, and umami).…”

“…The device was fabricated similarly to those previously described by the authors. 42 The e-tongue device analyzed electrolyte and nonelectrolyte liquids covering the basic tastes relevant for human gustatory perception (sweet, salty, sour, bitter, and umami). For this purpose, aqueous solutions of sucrose (C 12 H 22 O 11 ), NaCl, HCl, caffeine (C 8 H 10 N 4 O 2 ), and L-glutamic acid were prepared at 1 mM.…”

Controlled Insertion of Silver Nanoparticles in LbL Nanostructures: Fine-Tuning the Sensing Units of an Impedimetric E-Tongue

“…Briefly, as described in a previous publication [69], the microfluidic e-tongue setup consists of four IDEs linearly arranged on a gold-plated printed circuit board (Figure S3). Positioned along a single microchannel, these IDEs facilitate the propulsion of the analyte using a syringe pump.…”

A microfluidic sensor for continuously measuring membrane potential changes in interactions between taste substances and lipid polymer membranes

“…19) Pumping samples and buffer solutions through microfluidic channels enables dynamic changes in the adsorption and desorption of taste substances onto lipid polymer membranes, and we believe that objectively quantifying tastes perceived by humans may become possible. Various electronic tongues techniques [20][21][22][23][24] have been developed for microfluidic channels and flow injection bases. However, to the best of our knowledge, no previous studies have focused on temporal parameters because most methods are designed to minimize the volume of sample substance and the amount of time required for analysis.…”