“…Subsequently, the use of a large number of calix[4]arene derivatives for potentiometric measurements has been reported. Only minor changes in selectivities were found for other p - tert -butylcalix[4]aryl tetraesters, − but some improvements were obtained with short-chain esters and a mixed-ester compound (two decyl and two ethyl groups each ( Na + -21 ): log (SSM): K + , −2.6; Li + , −3.5; H + , −4.0; DOP, NaTFPB). , However, better selectivities resulted from the use of a calix[4]aryl tetraester with tert -octyl instead of tert -butyl groups ( Na + -22 , log (SSM): K + , −3.1; Li + , −4.6; Rb + , −5.1; Cs + , −5.8; FNDPE, KTpClPB) . Tetraesters have been tested for blood serum assays. ,,, …”
and 1991, respectively. He has been working in the field of chemical sensors since 1970. Further topics of his interest are spectroscopic databases, automatic spectra interpretation, and modeling of structure−property relationships. He has published over 180 papers and 7 books. Current activities in the fields of chemical sensors and computer-aided analytical chemistry are documented on the web page http://www/ceac.ethz.ch/pretsch/. His e-mail address is pretsch@ org.chem.ethz.ch.
“…Subsequently, the use of a large number of calix[4]arene derivatives for potentiometric measurements has been reported. Only minor changes in selectivities were found for other p - tert -butylcalix[4]aryl tetraesters, − but some improvements were obtained with short-chain esters and a mixed-ester compound (two decyl and two ethyl groups each ( Na + -21 ): log (SSM): K + , −2.6; Li + , −3.5; H + , −4.0; DOP, NaTFPB). , However, better selectivities resulted from the use of a calix[4]aryl tetraester with tert -octyl instead of tert -butyl groups ( Na + -22 , log (SSM): K + , −3.1; Li + , −4.6; Rb + , −5.1; Cs + , −5.8; FNDPE, KTpClPB) . Tetraesters have been tested for blood serum assays. ,,, …”
and 1991, respectively. He has been working in the field of chemical sensors since 1970. Further topics of his interest are spectroscopic databases, automatic spectra interpretation, and modeling of structure−property relationships. He has published over 180 papers and 7 books. Current activities in the fields of chemical sensors and computer-aided analytical chemistry are documented on the web page http://www/ceac.ethz.ch/pretsch/. His e-mail address is pretsch@ org.chem.ethz.ch.
“…Absorbent patches, microfluidic channels, and per-use washing may be considered as possible solutions. Second, selectivity of the ISEs against simple nontarget ions like K + , H + , and NH 4 + is likely to be high, as has been reported earlier. − However, selectivity against other constituents of sweat, especially lipophilic substances that can diffuse into the ISM, needs to be studied. Artificial sweat with controlled compositions can be used in such studies.…”
Section: Resultsmentioning
confidence: 84%
“…To make this material sensitive toward Na + ions, it was doped with 4- tert -butylcalix[4] arene-tetraacetic acid tetraethyl ester (sodium ionophore X) and ion exchanger potassium tetrakis((4-chlorophenyl)borate , (Figure S1). Sodium ionophore X was chosen owing to its high sensitivity to Na + ion and high selectivity against similar ions, such as K + and H + . − CNT-based flexible electrode arrays were prepared following a scheme shown in Figure a. The process utilizes standard photolithography and laser-cutting techniques.…”
Wearable electronics offer new opportunities in a wide range of applications, especially sweat analysis using skin sensors. A fundamental challenge in these applications is the formation of sensitive and stable electrodes. In this article we report the development of a wearable sensor based on carbon nanotube (CNT) electrode arrays for sweat sensing. Solid-state ion selective electrodes (ISEs), sensitive to Na ions, were prepared by drop coating plasticized poly(vinyl chloride) (PVC) doped with ionophore and ion exchanger on CNT electrodes. The ion selective membrane (ISM) filled the intertubular spaces of the highly porous CNT film and formed an attachment that was stronger than that achieved with flat Au, Pt, or carbon electrodes. Concentration of the ISM solution used influenced the attachment to the CNT film, the ISM surface morphology, and the overall performance of the sensor. Sensitivity of 56 ± 3 mV/decade to Na ions was achieved. Optimized solid-state reference electrodes (REs), suitable for wearable applications, were prepared by coating CNT electrodes with colloidal dispersion of Ag/AgCl, agarose hydrogel with 0.5 M NaCl, and a passivation layer of PVC doped with NaCl. The CNT-based REs had low sensitivity (-1.7 ± 1.2 mV/decade) toward the NaCl solution and high repeatability and were superior to bare Ag/AgCl, metals, carbon, and CNT films, reported previously as REs. CNT-based ISEs were calibrated against CNT-based REs, and the short-term stability of the system was tested. We demonstrate that CNT-based devices implemented on a flexible support are a very attractive platform for future wearable technology devices.
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