1530-437X (c) 2016 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/JSEN.2017.2671448, IEEE Sensors Journal > REPLACE WITH YOUR NAME AND SHORT VERSION OF TITLE (DOUBLE-CLICK HERE TO EDIT) < 1 Abstract— Sensors based on a conducting polymer, Polypyrrole (PPy), were fabricated to measure physiological variables used in clinical medicine as electrocardiography (ECG), impedance plethysmography (IPG) and body temperature. The fabrication process was also described, which had the advantage of producing disposable or even reusable electrodes. The electrodes were fabricated as membranes or bulk elements according to the requirements for their use. Furthermore, using a PPy/Polylactic acid (PLA) composite, a sensor flexible wristband for continuously measuring body temperature was also fabricated; changes in the PPy/PLA membrane resistivity were observed according to variations of temperature, thus, the response was characterized. Experimental results showed an almost linear and inversely proportional behavior between the temperature and the resistance of the PPy/PLA wristband sensor. The sensors-electrodes based on PPy have transducing functions and show the versatility of non-metallic elements for biomedical uses. This proposed system is a promising tool for medical care due to its reliability for using over a long period of time; thereby, making life easier for medical staff and increasing the quality of medical care for patients. Index Terms— Electrodes, ECG, Polymer, Polypyrrole, Temperature, Wristband, Flexible, Monitoring. I. INTRODUCTION HE material research has created new opportunity areas for engineers and scientist in the search of new solutions to typical demands in health care areas. All the novel technologies associated to this area have increased in the same magnitude. The miniaturization and the improvement in the capability and velocity of many medical devices is evidence of that. In the same way, a basic element, like the bioelectrodes, has acquired a great complexity in the design due to the specific requirements of their application. More comfortable and reliable designs have created to reduce skin-electrode impedance or to improve their behavior for long term recordings and so ensure an acceptable signal noise ratio [1-3] or like wearable devices, modifying the way that the user can get information about himself such as temperature, blood pressure, pulse without human intervention [4, 5]. Intrinsically conducting polymers (ICP) are semiconducting polymers, once doped either positively or negatively, have This study was supported in part by the Mexican Agency CONACYT through grant 151894. The authors are with the Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV), Electrical Engineering, Bioelectronics, MEX (e-mail:omartjmz@hotmail.com; grodriguezr@cinvestav.mx; hernandezr@cinvestav.mx; address contact: esuaste@cinvestav.mx ). electrical conductivity properties similar to metals. This characteristic arises from their backbone chemistry with alternating single and double bonds [6, 7]. Some of the most commonly used ICPs include PPy, poly(phenylacetylene), polyfuran, polyaniline and their derivates [8]. Applications include biosensors, bioactuators and printed electronics [7, 9, 10]. Polymer composites based on conductive polymers have demonstrated a great field of application on medicine as a result of improving properties like a larger sensing area, weight reduction, strength and flexibility enhanced, visible or infrared light sensibility and many other properties that open the application areas [11-13]. Conductive polymers composites have been also applied in drug release and electrical cell stimulation due to electrical properties. The aim of the composite is functionalize the polymers to modify parameters like biocompatibility, conductivity or porosity [14- 17]. Another property that can be adapted to the specific requirements of the application is their mechanical resistance [18, 19]. In this context, with the polymer electrodes, the contact area has been increased and improved as a consequence of their flexibility and adaptability to a great number of flat or curved surfaces; allowing the creation of wearable devices, modifying the way that the final user can get information about himself such as temperature, blood pressure, pulse without human intervention [4, 5]. Typically the non-metallic bioelectrodes presented now a days have probed their efficacy in ECG and electroencephalography (EEG) records [20-23]. However, bioelectrodes are required in other kind of useful non-invasive medical test. One of them is the impedance plethysmography (IPG), which has been an useful technique to reflect blood volume changes and can indirectly indicate the presence or absence of thrombosis measure [24] or where the bioelectrical impedance changes need to be monitored [25]. The technique uses an arrangement of electrodes that need to fit in an extremity of the body to receive and stimulate it with a small current and high frequency signal enough to correlate the impedance of the extremity with its blood volume. Body temperature is another vital physiological variable which is important to measure accurately. There are equipment such as thermal imaging cameras that successfully detect changes in body temperature without human intervention, nevertheless, these kind of devices are quite expensive [26]. Piezoresistive materials are widely used in biomedical Sensors based on conducting polymers for measurement of physiological parameters Omar Terán-Jiménez, Grissel Rodríguez-Roldán, Daniel Hernández-Rivera, Ernesto Suaste-Gómez T