Passive and wireless near field communication tag sensors for biochemical sensing with smartphone

Wireless, passive, low-cost and portable detection systems are in high demand for environment monitoring, food safety and health care diagnosis. Among them smartphone-based sensing systems are receiving special attention with the worldwide popularity of smartphones. Over the past decade, many devices, including a large number of smartphones in today's marketplace, are integrated with near field communication (NFC) modules. Leveraging the worldwide ubiquity of these devices, we developed wireless and passive NFC tag sensors based on flexible and low-cost NFC tags for biochemical sensing. NFC-enabled smartphone was used to wirelessly power the sensors and receive the detection results through inductive coupling. By adopting rheostats in the resonant circuits of the sensors, we easily achieved accurate semi-quantitative detection of different analytes constructed sensor arrays. The results demonstrated that the tag sensors could be used to discriminate gases at part-per-million concentrations and analytes in solution such as ions and bacteria in different concentration ranges. Thus, the wireless, passive, low-cost and flexible NFC tag sensors unfolded new dimensions for biochemical sensing with smartphones.