Photocurable Polymers for Ion Selective Field Effect Transistors. 20 Years of Applications

Abstract

Application of photocurable polymers for encapsulation of ion selective field effect transistors (ISFET) and for membrane formation in chemical sensitive field effect transistors (ChemFET) during the last 20 years is discussed. From a technological point of view these materials are quite interesting because they allow the use of standard photo-lithographic processes, which reduces significantly the time required for sensor encapsulation and membrane deposition and the amount of manual work required for this, all items of importance for sensor mass production. Problems associated with the application of this kind of polymers in sensors are analysed and estimation of future trends in this field of research are presented.

A liquid-junction-free reference electrode based on a PEDOT solid-contact and ionogel capping membrane

“…For equivalent ionogels formed using DMPP (--), the electrode potential increased less, i.e., 18.5 ± 1.9 mV and 30.5 ± 8.7 mV (n=4). This difference may arise from the presence of residual photo-initiator and its by-products in the membrane, as these are known to exhibit ion-exchange behaviour [25]. Thirdly, electrodes with membranes produced using PPODA (• • •) as cross-linker showed larger sensitivity towards Na + and K + than equivalent membranes produced using HDDA (--).…”

Physiological stress monitoring using sodium ion potentiometric microsensors for sweat analysis

“…In the frame of point of care applications, Na + potentiometric sensors, such as ion-sensitive electrodes (ISE) and ion-sensitive field effect transistors (ISFET), were preferentially studied using different ion-sensitive membranes. They can be either inorganic, focusing on the use of sodium aluminosilicate Na-AlSi 3 O 8 [18,19], either organic, emphasizing the use of sodium ionophores and polymers [20,21]. As far as polymers are concerned, poly-vinyl-chloride (PVC) [22][23][24][25][26], polyurethane (PY) [27,28], polypyrolle (PPy) [29], polysiloxane (PSX) [30][31][32][33] and fluoropolysiloxane (FPSX) [34,35] were studied, demonstrating fundamental differences in terms of physical properties and integration processes.…”

Application of Photocured Polymer Ion Selective Membranes for Solid-State Chemical Sensors

“…The extent of interference of highly lipophilic anions (e.g., CNS − ) in solution may be used as an indicator for the K-TpClPB content in the membrane. In Figure 1 calibration curves of sensors with membranes containing plasticizer and K-TpClPB and polymerized with different exposure times are presented along with the calibration curve for membrane without lipophilic anion [2]. From this figure it is clear that with the increase of the exposure time the cationic response of the membrane switches to anionic at much lower concentrations of KCNS due to the lower concentration of K-TpClPB.…”

“…In the case OPEN ACCESS of electrodes the major challenge was to obtain a fast and thermodynamically reversible ion to electron transduction system that may fix the potential at the solid-contact/ membrane interface [1]. For field-effect sensors it was necessary to find materials with very strong adhesion to fix an ion-selective membrane on a solid substrate by methods that are compatible with microelectronic technology [2].…”