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Hautefeuille M.,Tyndall National Institute | O'Flynn B.,Tyndall National Institute | O'Flynn B.,Clarity Center for Sensor Web Technologies | Peters F.H.,Tyndall National Institute | And 2 more authors.
Micromachines | Year: 2011

Recent progress in data processing, communications and electronics miniaturization is now enabling the development of low-cost wireless sensor networks (WSN), which consist of spatially distributed autonomous sensor modules that collaborate to monitor real-time environmental conditions unobtrusively and with appropriate levels of spatial and temporal granularity. Recent and future applications of this technology range from preventative maintenance and quality control to environmental modelling and failure analysis. In order to fabricate these low-cost, low-power reliable monitoring platforms, it is necessary to improve the level of sensor integration available today. This paper outlines the microfabrication and characterization results of a multifunctional multisensor unit. An existing fabrication process for Complementary Metal Oxide Semiconductor CMOS-compatible microelectromechanical systems (MEMS) structures has been modified and extended to manufacture temperature, relative humidity, corrosion, gas thermal conductivity, and gas flow velocity sensors on a single silicon substrate. A dedicated signal conditioning circuit layer has been built around this MEMS multisensor die for integration on an existing low-power WSN module. The final unit enables accurate readings and cross-sensitivity compensation thanks to a combination of simultaneous readings from multiple sensors. Real-time communication to the outside world is ensured via radio-frequency protocols, and data collection in a serial memory is also made possible for diagnostics applications. © 2011 by the authors. Source


Wang W.,Tyndall National Institute | Wang N.,Tyndall National Institute | Hayes M.,Tyndall National Institute | O'Flynn B.,Tyndall National Institute | And 3 more authors.
Applied Mechanics and Materials | Year: 2011

Wireless sensor networks are frequently used to monitor temperature and other manufacturing parameters in recent years. However, the limited battery life posts a constraint for large sensor networks. In this work, thermoelectric energy harvester is designed to effectively convert the heat into electrical energy to power the wireless sensor node. Bismuth telluride thermoelectric modules are optimized for low temperature conditions. Charge pump and switching regulator based power management module is designed to efficiently step up the 500mV thermoelectric voltage to 3.0V level for wireless sensor nodes. This design employs electric double-layer capacitor based energy storage with considerations on practical wireless sensor node operation. The implemented energy harvester prototype is proposed for Tyndall wireless sensor system to monitor temperature and relative humidity in manufacturing process. The prototype was tested in various conditions to discover the issues in this practical design. The proposed prototype can expect a 15 years operative lifetime instead of the 3-6 months battery lifetime. © (2011) Trans Tech Publications, Switzerland. Source


Vazquez P.,Tyndall National Institute | Vazquez P.,Clarity Center for Sensor Web Technologies | Herzog G.,CNRS Laboratory of Physical Chemistry and Microbiology for the Environment | O'Mahony C.,Tyndall National Institute | And 7 more authors.
Sensors and Actuators, B: Chemical | Year: 2014

This report describes a method for integration of a gel-liquid interface in hollow microneedles compatible with minimally invasive, electrochemical detection of drugs in vivo. The electrochemical sensor was characterised using cyclic voltammetry with tetraethyl ammonium. The experimental work demonstrated the detection of propranolol as a representative drug in physiological buffer with the microneedle system. A calibration curve for propranolol was built from measurements with differential pulse stripping voltammetry, indicating a sensitivity of 43 nA μM-1, a limit of detection of 50 nM and a linear range between 50 and 200 nM. © 2014 Elsevier B.V. Source


Wang W.S.,Tyndall National Institute | O'Donnell T.,Tyndall National Institute | Wang N.,Tyndall National Institute | Hayes M.,Tyndall National Institute | And 2 more authors.
ACM Journal on Emerging Technologies in Computing Systems | Year: 2010

For most wireless sensor networks, one common and major bottleneck is the limited battery lifetime. The frequent maintenance efforts associated with battery replacement significantly increase the system operational and logistics cost. Unnoticed power failures on nodes will degrade the system reliability and may lead to system failure. In building management applications, to solve this problem, small energy sources such as indoor light energy are promising to provide long-term power to these distributed wireless sensor nodes. This article provides comprehensive design considerations for an indoor light energy harvesting system for buildingmanagement applications. Photovoltaic cells characteristics, energy storage units, power management circuit design, and power consumption pattern of the target mote are presented. Maximum power point tracking circuits are proposed which significantly increase the power obtained from the solar cells. The novel fast charge circuit reduces the charging time. A prototype was then successfully built and tested in various indoor light conditions to discover the practical issues of the design. The evaluation results show that the proposed prototype increases the power harvested from the PV cells by 30% and also accelerates the charging rate by 34% in a typical indoor lighting condition. By entirely eliminating the rechargeable battery as energy storage, the proposed system would expect an operational lifetime 10-20 years instead of the current less than 6 months battery lifetime.© 2010 ACM 1550-4832/2010/06-ART8 $ 10.00. Source

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