Sensors and Actuators B 52 (1998) 257–263 Glucose biosensor strip in a three electrode configuration based on composite and biocomposite materials applied by planar thick film technology C.A. Gala ´n-Vidal a,c , J. Mun ˜oz b , C. Domı ´nguez b , S. Alegret a, * a Grup de Sensors & Biosensors, Departament de Quı ´mica, Uniersitat Auto `noma de Barcelona, 08193 Bellaterra, Catalonia, Spain b Institut de Microelectro `nica de Barcelona -CSIC, Campus Uniersitat Auto `noma de Barcelona, 08193 Bellaterra, Catalonia, Spain c Centro de Inestigaciones Quı ´micas, Uniersidad Auto ´noma del Estado de Hidalgo, 42076 Pachuca, Hidalgo, Mexico Received 22 December 1997; received in revised form 12 June 1998; accepted 16 June 1998 Abstract An amperometric glucose biosensor strip based on a three electrodes (counter, reference and working) planar configuration was fabricated using thick film technology. Glucose oxidase (GOD) was immobilized in the bulk of a graphite-epoxy composite paste. This paste was used to screen-print the working electrode on a glass fibre board. The integration on the same support of pseudo-reference electrode was obtained by screen printing a commercial silver-epoxy paste, and subsequent electrochemical chlorinization in KCl 1 M at +1 V (SCE). Finally, the counter electrode was integrated using the same technique by depositing a graphite-epoxy composite paste, taking into account the counter/working electrode area ratio. Response characteristics of a glucose biosensor strip based on this transducer are similar to those of previously reported one electrode configuration glucose biosensor constructed using the same biocomposite material [Gala ´n-Vidal and Mun ˜oz, Sens. Actuators B 45 (1997) 55–62]. © 1998 Elsevier Science S.A. All rights reserved. Keywords: Thick film technology; Screen-printing; Conductive pastes; Composites; Biocomposites; Biosensors; Glucose 1. Introduction The application of mass production techniques in the field of miniaturized biosensors such as thick film and microelectronic processing is resulting in low cost devices. The use of thick film techniques shows several significant advantages such as flexibility of design and choice of materials, low cost in infrastructure, possibil- ity of automation of the fabrication process and low barrier for technological transfer capability [2,3]. Fur- thermore, thick film technology permits the construc- tion of robust and reproducible solid-state electrochemical biosensors. The construction of such devices is commonly achieved by the sequential deposi- tion of thick films on a support by a screen-printing process [3]. A trend in the development of these biosensors has led to integrate together with the working electrode both reference and counter electrodes on one device in order to miniaturize and to simplify the instrumenta- tion and to extend the application potential for decen- tralised analysis. Recently, several contributions to this aim have been focused on the development of ampero- metric devices for determination of glucose, sucrose, lactose and ethanol [4–8]. In most of these devices, biosensing elements are sequentially immobilized on the base transducer layer, although some work is currently devoted to develop screen-printable conducting bio- composite materials in order to reduce the number of layers used in the fabrication process [6]. In these studies, complex preparation procedures for obtaining screen-printable biocomposites are normally needed [6,9]. * Corresponding author. Present address: Universitat Auto ` noma de Barcelona, Centro Nacional de Microelectro ` nica, IMB, E-08193 Bel- laterra, Spain. Tel.: +34 93 5802625; fax: +34 93 5801496; e-mail: pxm@cnm.es 0925-4005/98/$ - see front matter © 1998 Elsevier Science S.A. All rights reserved. PII S0925-4005(98)00276-7