engleski

RFID Smartcard Chemiresistors for Wireless Detection of Organic Vapours

Passive chemiresistor sensors with integral wireless power and data links are in development, and their potential applicability for the detection of organic vapors is demonstrated. The chemiresistors comprise a planar gold electrode array onto which chemically sensitive thin films are cast using micro-fabrication techniques. The thin film sensors are interfaced to a proprietary radio-frequency smartcard designed for use as a distributed chemical or biological detector, and which is compatible with the ISO15693 radio-frequency identification (RFID) wireless protocol. The measurement of thin film sensor resistance is performed by a four-contact method, and is controlled with on-card electronics. Thin polymer films based on the organic semiconductors 3, 4-ethylenedioxythiophene-poly(styrenesulfonate) (PEDOT-PSS) and polyaniline (PANI) have been used as chemically sensitive thin films to demonstrate function of this platform for detection of gaseous analytes. Potential applications of smartcard chemiresistors include mobile and wearable sensors for chemical exposure and contamination monitoring and smart personal diagnostics. The standardization of short-range wireless radio protocols such as Bluetooth, RuBee, ZigBee, WiFi and RFID is creating new markets for distributed sensors and sensor networks, and the fusion of chemical and biosensor technologies with short-range, low-cost, wireless technologies will create new opportunities for chemical and biological sensor systems in healthcare, environmental monitoring, process and quality control, and chemical and biological threat detection [1]. We are developing high-value applications beyond typical cool-chain temperature tracking by designing novel sensors onto custom RFID labels compatible with the ISO15693 smartcard protocol. The RFID protocol is particularly suitable for short-range contactless sensor applications, since it supports both passive (batteryless) and semi-passive (powered) devices and has an anti-collision protocol that supports reading of up to 255 sensors in a single scan. This work is concerned with developing and integrating conductometric chemiresistor sensors onto a short-range wireless platform with which to address a subset of these emerging applications. RFID-based sensor chips are now commercially available for temperature logging [4], and investigational chemical devices have been reported for both gases [5] and vapors [6]. We have developed a custom RFID processor and antenna onto a credit-card sized device [fig.1] which includes a conductometric sensor interface [fig.2]. The smartcard interfaces with a low-cost disposable part on which the chemiresistor is fabricated [fig.3]. First results demonstrate a reversible response of the sensors on exposure to ethanol vapour [fig.4]. The smartcard chemiresistors described here could in future be suitable for use in distributed wireless data applications and chemical sensor networks where organic vapours are to be detected.

organic vapours; chemiresistor sensors; radio frequency identification wireless protocol (RFID); organic semiconductors

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