Chem. Anal. (Warsaw), 51, 909 (2006) Keywords: Back-side contact sensors; Self-assembled monolayers; Ion-selective electrodes; Voltammetric sensors; Dopamine determination Monolayer Modified Back-Side Contact Silicone-Based Miniaturized Sensors for Electrochemical Applications by £ukasz Górski*, Ewa Grygo³owicz-Pawlak, Agata Rudzka, Kamila P³achecka and El¿bieta Malinowska Faculty of Chemistry Warsaw University of Technology, ul. Noakowskiego 3, 00664 Warsaw, Poland Miniaturized back-side contact (BSC) sensors with inner gold electrode modified with self- -assembled monolayers (SAM) have been utilized as potentiometric and voltammetric sen- sors. Na + , H + , K + and Ca 2+ -selective electrodes were obtained by modification of BSC sen- sors with ferrocene-terminated thiol-based monolayer and photocured polyacrylate mem- brane. The obtained sensors exhibited near-Nernstian responses, comparable with the res- ponses of conventional PVC or silicon rubber-based electrodes described in the literature. Other parameters, i.e. linear ranges and selectivity coefficients seemed to be even better in case of the designed sensors. The possibility of application of the designed BSC transducer in voltammetric detection has been also examined. Determination of dopamine in the pre- sence of ascorbic acid has been chosen as a model system. For this purpose, inner gold electrode was modified with a monolayer of N-acetylcysteine. As it was reported earlier in the literature, good separation of the oxidation potentials of these compounds has been obtained. W niniejszej pracy zosta³y przedstawione wyniki badañ nad konstrukcj¹ sensorów poten- cjometrycznych i woltamperometrycznych z zastosowaniem miniaturowych przetworników z elektrod¹ z³ot¹ i tylnym wyprowadzeniem kontaktu elektrycznego. Elektrody selektywne na jony Na + , H + , K + oraz Ca 2+ zosta³y przygotowane przez modyfikacjê czujników mono- warstw¹ tiolow¹ z grupami ferrocenowymi oraz poprzez naniesienie fotopolimeryzowanej membrany poliakrylanowej. Wytworzone sensory charakteryzowa³y siê odpowiedzi¹ blisk¹ nernstowskiej, bardzo zbli¿on¹ do odpowiedzi klasycznych elektrod z membranami z PCW oraz z gumy silikonowej. Inne parametry, takie jak zakres liniowej odpowiedzi oraz wspó³- czynniki selektywnoci, by³y nawet lepsze dla badanych miniaturowych sensorów. Sensory * Corresponding author. E-mail: lukegor@ch.pw.edu.pl