Electrochemical detection of biogenic amines during food spoilage using an integrated sensing RFID tag

Abstract

This work outlines a new approach for modifying conventional RFID tags with chemically sensitive conductive composites. Conductive composite films were integrated into the RFID tag circuit. As the film was exposed to selected analytes the film swelled increasing the resistance of the film and decreasing the communicating ability of the RFID tag. Using maleic anhydride as the sensing material, the composite was able to detect different biogenic amines associated with food spoilage. RFID tag response was found to depend on amine concentration, tag initial resistance and type of biogenic amine. RFID sensors of this nature are attractive for a number of applications in the gaseous sensing industry.

Introduction

Amine identification and quantification is challenging because underivatized amines are difficult to separate in common liquid and gas chromatography columns. We are interesting in developing portable amine sensors with the goal of detecting amines produced during food spoilage. This objective is particularly challenging because both aliphatic and aromatic di and tri-amines are present in these samples. Traditional analytical techniques such as gas chromatography coupled to mass spectrometry are plagued because samples containing multiple amines must be derivatized to be sufficiently separated. In addition this technique is costly, time consuming and requires a trained technician.

Food spoilage occurs as enzymes in bacteria decarboxylize amino acids to form biogenic amines. A number of volatile components are emitted during food spoilage including alcohols, esters, and ethylene; but are focus is to detect amines because of their biogenic effect. Biogenic amines are volatile organic molecules that make-up the toxic component of spoiled food and they are a direct indicator to detect food spoilage in meat, fish, wine, cheese and other food stuffs [1], [2], [3], [4]. Biogenic amines have been detected in food primarily using liquid chromatography, [5], [6] but other methods such as capillary electrophoresis, [7], [8] mass spectrometry, [9], [10], [11], [12], [13] ion mobility spectrometry, [14] colorimetric, [15], [16] metal oxide sensors [17] and electronic nose sensors [18], [19] have also been employed to detect biogenic amines. There are several detriments to these techniques: extensive sample preparation is required, instrumentation is expensive and requires a skilled technician, sample measurements must be done in a laboratory setting and these techniques are invasive to the sample. For these reasons, portable sensors have been developed to perform food spoilage detection by measure changes in temperature, pH or evolved gas [20], [21], [22], [23], [24]. These sensors have many advantages: they are cost effective, they can be incorporated into food packaging and the sensor can be interpreted by any user. These sensor function by monitoring bacteria stimulus such as the temperature the food is stored in and extrapolate from this the count of bacteria on the food stuffs and the amount of biogenic amines produced using a statistical prediction. The disadvantage of this is the margin of error in the statistical analysis of bacterial growth, a prediction that underestimates bacterial growth can make a person very ill.

One emerging approach to performing analysis of volatile molecules encompasses attaching an absorbing polymer film to an electronic sensor. This technique uses changes in the electronic properties of polymer sensing film to detect volatile chemicals as they absorb to the polymer film [25], [26], [27], [28], [29]. Using an impedance analyzer several parameters of the polymer film such as real and imaginary impedance spectra could be measured to identify and quantify different vapours. This method has had limited success detecting amines [12], [18], [19]. The disadvantages of this work include using expensive Nafion film as the sensing film, needing a network analyzer to perform readings, readings are position-dependant for analyte quantitation and relying on multivariate statistical analysis methods for identification and quantification. Others have combined sensing devices with RFID tags to achieve ‘wireless chemical and biological sensing’ [30], [31], [32], [33], [34], [35].

This paper describes a new method for chemically sensing biogenic amines using smarter RFID tags. Conventional, cost effective passive RFID tags were modified for these experiments. Contrary to other approaches that attached a sensor to the RFID antenna, this method integrates a conducing composite into the RFID tag. When the composite swells the RFID tag optimal frequency for reflecting radio waves shifts to a lower frequency and the amount of radio waves reflected back decreases. The response of the RFID tag was shown to a function of amine concentration as well as composite resistance. Detection was demonstrated with biogenic amines relevant to food spoilage: putrescine, histamine, cadaverine, spermine and spermidine. The sensing film swells in the presence of volatile biogenic amine and de-swells when the stimulus is removed, therefore these sensors can be reused. In this way RFID tags have the ability to track their product but also measure the quality of the delivered product.