Passive Telemetric Readout System

A technique for remote query monitoring of environmental parameters such as pressure, humidity, complex permittivity, temperature, strain, and gases such as carbon dioxide, oxygen, and ammonia is presented. Resonant peak passive telemetry is used for wireless remote monitoring. The resonance frequency of an inductor-capacitor sensor circuit changes with the surrounding environmental parameter, and a detector circuitry, which employs a loop antenna, is used to remotely identify the resonance frequency. Mutual coupling between the antenna and the sensor inductor enables wireless monitoring. Various detection techniques available for monitoring the sensor resonance frequency are examined, and a new method is presented for automated and continuous wireless detection of sensor resonance frequency. Results are presented for different sensor resonance frequencies using various sensor capacitance values. The designed system can effectively detect sensor resonance frequency variation in the range of 20 kHz-10 MHz with the highest achievable resolution of 0.01 MHz. Sensor resonance frequency changes that occur faster than 1 s cannot be detected. The automated continuous wireless remote sensor platform design provides significant advantage over past systems, and the entire design is simple, easy to use, and widely applicable for in vivo, in vitro, and in situ monitoring