RWV Sensor Array For Metal Ions Detection

The development of sensor for detecting metal ions has attracted many researchers'interest.Colorimetric sensor has become the preferred detection because of its convenience and rapidity,but it is limited by natural light conditions.This paper is committed to develop a new type of sensor,reaction wettability sensor,whose principle is based on the surface wettability changes caused by the reaction between analyte and test objection.This sensor array can be used as a supplement to the colorimetric sensor.The main contents are as follows:1.A sensor unit is fabricated by implanting photo responsive azoimidazole(Azolm)ligands on an electrospun polymer membrane.Due to that the response variation of each analyte is influenced by the membrane-forming polymer and the conformation of AzoIm,the sensor is expanded into a sensor array to offer a more accurate on-site detection.The principle component analysis(PCA)is further applied to evaluate the detection performance and influential structural factors of the array on those ions.The differential response it works on results from varied binding constants of ion-AzoIm complexes and pH of the analyte solutions.Moreover,the detection of metal ions is extended to the bioinorganic molecule of hemin in the same mechanism.2.To achieve an enhancement of the reactional wettability variation(RWV)sensing strategy,the sensor unit is changed and formed by coating hydrophobic azoimidazole compounds,as the responder compounds onto the originally hydrophilic surface of cobalt oxide nanoneedles.The reactional basis of the complexation between the metal ions and azoimidazole ligands etches the hydrophobic coating and switches the surface wettability to hydrophilic.This switch is revealed by a decrease in the static contact angle(CA)and an increase in the sliding angle of the surface.A sensor array composed of six as-tuned sensor units is constructed to distinguish among the species and the concentrations of Fe3+,Ni2+and La3+analytes at a low limit of 10"6 M using the chemometric method of principal component analysis.In addition,a new on-site detection strategy is developed based on PCA of the sliding angle,which can be measured conveniently and swiftly with a smartphone app and a commercially available setup.In this paper,two sensors for detecting metal ions have been built based on different sensor units,and through mixing with different polymers or modifying homologue,sensor was expanded to a sensor array.Chemical pattern recognition was applied to distinguish several different metal ions.We believe this kind of sensor based on wettability change has great potential in other detection direction.