Alexey Savkin

Energy-Aware gas sensing using wireless sensor networks

Wireless Sensor Networks (WSN) have recently been applied in various monitoring applications including hazardous gases detection. However, being a major power consumer of a sensor node, off-the-shelf gas sensors significantly constrain its lifetime. In this paper we present a WSN for hazardous gases detection with a special focus on the power consumption of the sensor node. The sensor node is designed on the basis of a planar catalytic sensor with improved power consumption characteristics. The power supply of the node is divided into digital and analogue parts. This is done to guarantee digital remote control of the device even when the analogue power source has already been depleted by the sensing circuit. In addition, we propose a differential gas measurement approach along with specific heating pulses for the sensor to secure substantial energy saving. The resulting average power consumption is 1.45 and 2.64 mW for the gas sensor and the sensor node respectively. With our techniques, the sensor node lifetime improves from 187 days up to 641 days.

Combustible gases and early fire detection: an autonomous system for wireless sensor networks

Fires or toxic gas leakages may have grave consequences like significant pecuniary loss or even lead to human victims. In this paper we present an autonomous wireless sensor system for early fire and gas leak detection. The system consists of two modules: a gas sensor module and a power management module. The operation of the gas sensor module is based on the pyrolysis product detection which makes it possible to detect fire before inflammation. In addition, the on board gas sensor can identify the type of leaking gas. A generic energy scavenging module, able to handle both alternating current and direct current based ambient energy sources, provides the power supply for the gas sensor module. The harvested energy is stored in two energy buffers of different kind, and is delivered to the sensor node in accordance to an efficient energy supply switching algorithm. At the end of the paper we demonstrate the experimental results on gas detection, energy consumption evaluation, and show how to ensure the system autonomous operation.

LED-based NDIR natural gas analyzer

A new generation of the light-emitting diodes (LEDs) and photodiodes (PDs) was used recently to develop an open path non-dispersive infrared (NDIR) methane analyzer. The first open path detector prototype was constructed using LEDs for measurement and reference channels, accordingly, and first measurements for methane gas have been performed using optical paths of the order of several meters [3]. The natural gas consists of several first alkanes, mainly methane, and it is important to have a possibility of measuring all of them. In the present work we report the results of NDIR measurements for propane-butane mixture and new measurements of methane using LEDs for measurement and reference channels at 2300 and 1700 nm wavelengths, accordingly. The necessity of the double beam scheme is demonstrated and obtained results for methane and propane-butane mixture are compared.

Energy Efficient Trade-Off between Communication and Sensing in Wireless Gas Sensor Node

A wireless sensor network is a distributed collection of resource constrained tiny nodes capable of operating with minimal user attendance. Communication circuit is normally the most power consuming part of sensor node. Depending on the application, the node may have on board various extra hardware components with even higher power consumption. These components can impose restrictions in terms of providing the same communication range without increasing power consumption. In this paper we investigate the energy efficient balance between the communication and sensing modes in a gas sensor node. First, we analyze how to secure the energy efficient sensing of environment using the developed framework. Then we establish the efficient transmission power rate for each sensing power level. Finally, the effective distances for the appropriate transmission rates are defined.

Non-dispersive LED-based methane open path detector capabilities

Development of the new light sources for middle infrared region opened new perspectives for methane detection. Possibilities of non-dispersive infra-red open path methane detector operating at 2.3 μm wavelength are discussed. Analytical model of NDIR methane sensor is considered and detector calibration curve for LEDs is presented. The effects of the influence of the methane concentration and the atmospheric precipitations on detector sensitivity are discussed.

Multicomponent hydrocarbons monitoring by infrared LED arrays

The use of new infrared LED arrays for NDIR multicomponent gas analysis is considered. Model spectra for bi component gas mixtures are simulated and the concentration reconstruction method is discussed.

A Multisource Energy Harvesting Platform for Wireless Methane Sensor

Sensors used for detecting combustible gases consume significant amounts of power. Energy management for these sensors can become an important issue when they are used as part of a wireless sensor network. This is because of the fact that wireless sensors are usually powered by batteries. Batteries have a finite lifetime and their replacement can take a considerable amount of time in a gas monitoring application where thousands of sensor nodes are deployed to measure the concentration of flammable gases. Moreover, the battery replacement procedure can turn into a more complicated task if the gas monitoring network is located in a harsh environment. Energy harvesting is a method which can increase the operation time of wireless gas sensor networks. In this article, we present a multisource harvesting circuit for a wireless gas sensor node. As for ambient sources, we have chosen solar and wind energy. Energy from ambient sources is stored in supercapacitors which have a capacity of 400 F. We prove that a catalytic gas sensor can operate for 2 days without batteries by using the developed scheme.

Multi-wavelength IR method for monitoring air pollution in cities

In this work we address the problem of air pollution in modern cities. We propose a method for detection and analysis of evaporation (H2O), carbon dioxide (CO2), carbon monoxide (CO) and methane (CH4) which are the typical components of exhaust gases produced by the gasoline vehicles. The method is based on infrared multi-wavelengths absorption in the range of 1.3-2.3 μm and can be implemented by using multi waves array of light emitting diodes (LEDs). The proposed approach allows several absorption spectra to be covered by one LED absorption line, thus the number of used LEDs should be not less than the number of considered absorption lines. The simulation was done for a 6-element multi-wavelengths LED array. We demonstrate that the method is highly relevant for the application to open-path detectors where the radiation source and the receiver are located at a distance of tens of meters from each other.

Light emitting diode absorption spectroscopy for combustible gas monitoring

A new generation of the infrared light-emitting diodes (LEDs) and photodiodes (PDs) was used to construct an open path non-dispersive infrared (NDIR) methane analyzer. It was shown earlier that its characteristics are suitable for usual alarm systems, but new measurements have shown that cross sensitivity to other alkanes is rather high.