Development of Durable Nitrate-Selective Membranes for All-Solid State ISE and ISFET Sensors Based on Photocurable Compositions

Abstract

Novel nitrate‐sensitive membranes have been developed using an aliphatic urethane diacrylate photocurable polymer. This polymer has been chosen due to its easy and fast deposition procedure compared with PVC membranes and its compatibility with microelectronic techniques. These membranes were obtained after UV irradiation during no more than 60 seconds. To optimize their composition and evaluate the chemical response ion selective electrodes (ISEs) with solid inner reference were used. Studies of different plasticizers for nitrate PVC membranes and compositions increasing the ratio between oligomer and diluting agent were performed. ISEs developed presented a sensitivity of −56 mV/dec and a lifetime up to one year. Membrane compositions containing dibutyl phthalate and trioctyl phosphate as plasticizers were deposited onto ISFETs. Studies to elongate ISFETs lifetime were carried out modifying the encapsulation methodology, by using the same polymer family. ISFETs showed a sensitivity between 65–69 mV/decade, depending on the plasticizer, and a linear range of 2.4×10−5−0.06 M. The long‐term stability of ISFET sensors with trioctyl phosphate plasticizer was up to 10 months, being superior to that described in the literature for PVC membranes and even for other kind of polymers.

Portable Electronic Tongue Based on Microsensors for the Analysis of Cava Wines

“…All of these ionophores are selective to the principal ion, but are not specific and they present a certain degree of cross-response to other ions in solution. Membrane composition and preparation has been presented elsewhere [29,30,31,32]. An Orion 90-02-00 double junction Ag/AgCl reference electrode (Thermo Electron, Waltham, MA, USA) with 0.1 M CH 3 COOLi solution in its outer chamber was employed for all of the potentiometric measurements.…”

“…All of these microsensors present a long-term stability above seven months with discrete calibrations in aqueous solutions [29,30,31,32,33]. However, their lifetimes are, in fact, limited by their use, so that in a continuous monitoring application, for example in Cava wine production, their response characteristics (sensitivity, selectivity) would degrade within 2–3 months.…”

ISFET Based Microsensors for Environmental Monitoring

“…Ionic membranes for ISFETs were based on photocurable polymers which provided long-term stability of the sensors. Those were stable over nine months in aqueous solutions and up to two months inserted in soil as shown in Figure 6b [ 26 , 84 , 85 ]. Analysis data of several extracted soil samples from rose pots with loam or pet soil were compared with those obtained with standard methods showing a good agreement between both methods.…”

Classification and Characterization of Different White Grape Juices by Using a Hybrid Electronic Tongue

“…Therefore, this set of sensors provides information about the concentration of some key ions in the grape juice. Membrane composition and preparation are presented elsewhere. − The generic ISFET for anions was duplicated in the used array. An Orion 90-02-00 double junction Ag/AgCl reference electrode (Thermo Fisher Scientific, Waltham, MA, USA) with 0.1 mol/L CH 3 COOLi solution in its outer chamber was employed for all these potentiometric measurements.…”