A miniaturised autonomous sensor based on nanowire materials platform: the SiNAPS mote

A micro-power energy harvesting system based on core(crystalline Si)-shell(amorphous Si) nanowire solar cells together with a nanowire-modified CMOS sensing platform have been developed to be used in a dust-sized autonomous chemical sensor node. The mote (SiNAPS) is augmented by low-power electronics for power management and sensor interfacing, on a chip area of 0.25mm2. Direct charging of the target battery (e.g., NiMH microbattery) is achieved with end-to-end efficiencies up to 90% at AM1.5 illumination and 80% under 100 times reduced intensity. This requires matching the voltages of the photovoltaic module and the battery circumventing maximum power point tracking. Single solar cells show efficiencies up to 10% under AM1.5 illumination and open circuit voltages, Voc, of 450-500mV. To match the battery’s voltage the miniaturised solar cells (~1mm2 area) are connected in series via wire bonding. The chemical sensor platform (mm2 area) is set up to detect hydrogen gas concentration in the low ppm range and over a broad temperature range using a low power sensing interface circuit. Using Telran TZ1053 radio to send one sample measurement of both temperature and H2 concentration every 15 seconds, the average and active power consumption for the SiNAPS mote are less than 350nW and 2.1 μW respectively. Low-power miniaturised chemical sensors of liquid analytes through microfluidic delivery to silicon nanowires are also presented. These components demonstrate the potential of further miniaturization and application of sensor nodes beyond the typical physical sensors, and are enabled by the nanowire materials platform

MISAT: Designing a Series of Powerful Small Satellites Based upon Micro Systems Technology

MISAT is a research and development cluster which will create a small satellite platform based on Micro Systems Technology (MST) aiming at innovative space as well as terrestrial applications. MISAT is part of the Dutch MicroNed program which has established a microsystems infrastructure to fully exploit the MST knowledge chain involving public and industrial partners alike. The cluster covers MST-related developments for the spacecraft bus and payload, as well as the satellite architecture. Particular emphasis is given to distributed systems in space to fully exploit the potential of miniaturization for future mission concepts. Examples of current developments are wireless sensor and actuator networks with plug and play characteristics, autonomous digital Sun sensors, re-configurable radio front ends with minimum power consumption, or micro-machined electrostatic accelerometer and gradiometer system for scientific research in fundamental physics as well as geophysics. As a result of MISAT, a first nano-satellite will be launched in 2007 to demonstrate the next generation of Sun sensors, power subsystems and satellite architecture technology. Rapid access to in-orbit technology demonstration and verification will be provided by a series of small satellites. This will include a formation flying mission, which will increasingly rely on MISAT technology to improve functionality and reduce size, mass and power for advanced technology demonstration and novel scientific applications.

An ultra-low power energy-efficient microsystem for hydrogen gas sensing applications

This paper presents a fully integrated power management and sensing microsystem that harvests solar energy from a micro-power photovoltaic module for autonomous operation of a miniaturized hydrogen sensor. In order to measure H-2 concentration, conductance change of a miniaturized palladium nanowire sensor is measured and converted to a 13-bit digital value using a fully integrated sensor interface circuit. As these nanowires have temperature cross-sensitivity, temperature is also measured using an integrated temperature sensor for further calibration of the gas sensor. Measurement results are transmitted to the base station, using an external wireless data transceiver. A fully integrated solar energy harvester stores the harvested energy in a rechargeable NiMH microbattery. As the harvested solar energy varies considerably in different lighting conditions, the power consumption and performance of the sensor is reconfigured according to the harvested solar energy, to guarantee autonomous operation of the sensor. For this purpose, the proposed energy-efficient power management circuit dynamically reconfigures the operating frequency of digital circuits and the bias currents of analog circuits. The fully integrated power management and sensor interface circuits have been implemented in a 0.18 mu m CMOS process with a core area of 0.25 mm(2). This circuit operates with a low supply voltage in the 0.9-1.5 V range. When operating at its highest performance, the power management circuit features a low power consumption of less than 300 nW and the whole sensor consumes 14.1 mu A

An ultra-low power energy-efficient microsystem for hydrogen gas sensing applications

This paper presents a fully integrated power management and sensing microsystem that harvests solar energy from a micro-power photovoltaic module for autonomous operation of a miniaturized hydrogen sensor. In order to measure H2 concentration, conductance change of a miniaturized palladium nanowire sensor is measured and converted to a 13-bit digital value using a fully integrated sensor interface circuit. As these nanowires have temperature cross-sensitivity, temperature is also measured using an integrated temperature sensor for further calibration of the gas sensor. Measurement results are transmitted to the base station, using an external wireless data transceiver. A fully integrated solar energy harvester stores the harvested energy in a rechargeable NiMH microbattery. As the harvested solar energy varies considerably in different lighting conditions, the power consumption and performance of the sensor is reconfigured according to the harvested solar energy, to guarantee autonomous operation of the sensor. For this purpose, the proposed energy-efficient power management circuit dynamically reconfigures the operating frequency of digital circuits and the bias currents of analog circuits. The fully integrated power management and sensor interface circuits have been implemented in a 0.18μm CMOS process with a core area of 0.25mm2. This circuit operates with a low supply voltage in the 0.9-1.5V range. When operating at its highest performance, the power management circuit features a low power consumption of less than 300nW and the whole sensor consumes 14.1μ

Distributed environmental monitoring

With increasingly ubiquitous use of web-based technologies in society today, autonomous sensor networks represent the future in large-scale information acquisition for applications ranging from environmental monitoring to in vivo sensing. This chapter presents a range of on-going projects with an emphasis on environmental sensing; relevant literature pertaining to sensor networks is reviewed, validated sensing applications are described and the contribution of high-resolution temporal data to better decision-making is discussed

MEMS Devices for Miniaturized Gas Chromatography

In the era of the Internet of Things, the need for mobile devices able to analyze accurately real samples with sometimes very small volumes is a must. Gas chromatography (GC) is a common laboratory technique widely used for analyzing semi-volatile and volatile compounds. However, this technique is not suitable to be used outside labs. The development of micro-machined processes encouraged the development of miniaturized gas chromatographs. This chapter focuses on the recent development in the field of miniaturized gas chromatography and its component up to the present in various fields of analyses