Low-power wireless trace gas sensing network

摘要

A basic wireless laser spectroscopic sensor network for monitoring of trace-gases will be presented. The prototype lowpower sensor nodes targeting carbon dioxide are based on tunable diode laser absorption spectroscopy and operate using a 2 μm VCSEL and a 3.5 m Herriott multi-pass cell. The sensor system, which employs real-time wireless communications, is controlled by custom electronics and can be operated autonomously. The sensor core electronics performs molecular concentration measurements using wavelength modulation spectroscopy with an active laser frequency locking to the target transition. The operating sensor node consumes approximately 300 mW of electrical power and can work autonomously for up to 100 hours when powered by a 10.5 Ah Lithium-ion polymer battery. Environmentally controlled long term (12 hours) stability tests show sensor node detection limit of ~0.286 ppm with 1 second integration time and the ultimate minimum detectable fractional absorption of 1.5x10-6 is obtained after 3500 seconds averaging time. The sensor node performance results and preliminary tests in a basic network configuration are discussed.