FET Based Heavy Metal Ion Selective Sensors for Lead Ion Detection in Whole Blood

Abstract

With significant industrial development, heavy metal pollution is worsening and causing serious environmental and health issues. Until now, if people want to check for heavy metal contamination in their environment, they have to send the sample to laboratory, and wait for several days to get back the results. In this study, we developed a lead ion selective sensor which can rapidly detect lead ion in whole blood, in the convenience of home/office. Previously, our group developed a high sensitivity FET biosensor to detect proteins in physiological fluids. Following this methodology we had developed ion selective membrane (ISM) FET sensor for heavy metal ion detection in tap water. The present research combines novel extended gate FET structure and lead ISM, and demonstrates the detection of lead ion in whole blood. The ion selective sensor consists of ISM, narrowly separated metal electrodes and field effect transistor (FET) for signal transduction. In this structure, there are two gold electrodes on the epoxy substrate, one is sensing electrode and another one is reference electrode. The sensing electrode is connected to the FET, and we apply short pulse gating voltage to the reference electrode. The high field modulation of FET enables good signal to noise ratio. The ion selectivity membrane (ISM) consists of lead ionophore IV, tetraphenylborate, 2-Nitrophenyl octyl ether (2NOE) and Poly vinyl chloride (PVC). The ISM is selectively immobilized on the reference and sensing electrodes. In order to avoid the interference of cells in whole blood during the electrical measurement, we will invert the chip to faces downwards, to gravitationally separate the cells, allowing only blood plasma to contact the ISM. Our ISM-FET sensor has a short response time of 15 minutes, and the operation method is quite easy and convenient which is suitable for home-care, as opposed to laboratory standard equipment like ICP-MS. This ion selective sensor has a comparable detection limit with ICP-MS (detection limit of Pb2+: 10-10 M). Figure 1