Dr Rod Shepherd, B.Env.Sc. (Hons), PhD

roderick.shepherd@dcu.ie

Background

The aim of this project is to develop low power wireless sensor networks for environmental monitoring. A key feature of the work is the incorporation of low cost LED based chemical sensors, which have been developed recently in collaboration with Mitsubishi Electric Research Labs (MERL). These devices offer both sensing and line-of-sight wireless communication in a single package, adding an extra dimension to the network.

The project is currently in the very initial stages, and hence a commercial self-organising wireless platform is being evaluated. In the future we plan to develop and implement our own custom hardware for deployment in real environmental monitoring scenarios.

Results

To date we have developed simple optical chemical sensors based on LEDs and light dependent resistors (LDRs), which we have successfully interfaced to nodes in a small wireless network. A voltage is fed from the sensor to an ADC on the node, and this value is then sent by RF to a base station. We are currently in the process of interfacing more sensitive all LED sensors to the nodes, which we plan to use in a range of scenarios.

Different colour states of LDR sensor, in air (green) and after exposure to acetic acid (yellow).

We have constructed a test chamber, which is equipped with a range of controls allowing for the manipulation of plumes. Initial testing will involve plumes of smoke, which will be monitored using a combination of optical LED sensors and cameras. At later stages of testing chemical LED sensors will be employed to track real chemical plumes.

Test chamber for plume generation.

Partners

MERL

Funding

SFI03/IN3/1361

Outcomes and Activities

Publications

Novel fused-LEDs devices as optical sensors for colorimetric analysis, K.T. Lau, S. Baldwin, R.L. Shepherd, P.H. Dietz, W.S. Yerazunis and D. Diamond, Talanta, 63(1) 167-173 2004.

Visits

2003 - Visiting Research Scientist, Mitsubishi Electric Research Laboratories, Cambridge MA 02139, USA.