Global environmental micro sensors stir winds of change for atmospheric monitoring

Citation

(2006), "Global environmental micro sensors stir winds of change for atmospheric monitoring", Sensor Review, Vol. 26 No. 3. https://doi.org/10.1108/sr.2006.08726cab.006

Global environmental micro sensors stir winds of change for atmospheric monitoring

Global environmental micro sensors stir winds of change for atmospheric monitoring

ENSCO, Inc. uses very small technology to potentially lend big improvements to weather forecasting

Keywords: Sensors, Environmental testing

Amidst the balmy breezes and swaying palm trees of East Central Florida, forward-looking technologists at ENSCO, Inc. are working to create a revolutionary observing system known as Global Environmental Micro Sensors (GEMS). ENSCO's interdisciplinary team of scientists and engineers are using advances in micro electro mechanical systems and nanotechnology to provide the scientific community with a system of atmospheric probes that passively float with the wind. GEMS offer the unique potential to expand the amount of in situ environmental observations beyond what is currently available – especially over data sparse regions of the Earth. The expanded data sets provided by GEMS are expected to improve weather forecast accuracy and efficiency well beyond what is currently available. These improvements can help to mitigate risk factors associated with life-threatening weather phenomena and offer potentially significant economic savings for weather sensitive industries world wide. Potential savings for the US energy industry have been estimated to be as much as $400 million per year assuming GEMS data improve regional low-level temperature forecasts by ~0.5°C.

The GEMS concept was initially seeded as an internal research and development effort by ENSCO. Later, Dr John Manobianco, creator of the concept and ENSCO's Director of Advanced Technologies was awarded funding by the NASA Institute for Advanced Concepts (NIAC) over two phases. The first phase focused on identifying the major feasibility issues associated with creating the GEMS system – probe design, power, communication, networking, signal processing, sensing, deployment, dispersion, data impact, data collection and management, costs, and operational/environmental concerns. The second phase, which concluded in August 2005, studied each of these issues in detail. A large number of design trade-offs were found based on these feasibility issues. Modeling and simulation were used extensively in both phases as a cost-effective and controlled way to study the trade-offs and map out pathways for further system development.

The phase I GEMS concept initially envisioned ultra low-cost, disposable devices as small as 50-100 μm in one or more dimensions, with each probe housing on-board power, communications, processing, and sensing capabilities. During the course of the phase II study, the original idea to pursue miniaturization of the entire probe toward the micron size was modified based on communication, power, and terminal velocity requirements. One of the design trade- offs favouring larger devices was the requirement for probes to remain airborne for weeks to months. In the near term, maximizing the time probes remain airborne is most easily achieved using a self-contained, constant altitude vessel filled with a lighter-than-air gas to make each probe neutrally buoyant. Power will be generated by thin-film solar cells and stored in super- capacitors or small lithium ion batteries. The electronics, minus the sensors, will be encapsulated by a thin helium-filled polyester shell such as Mylar™. The probes will use one-way RF communication with low-earth orbiting satellites to provide data exfiltration. The general design approach for the probe will allow an interoperable sensor suite so that the GEMS system could make a variety of environmental measurements. In addition to wind and other meteorological parameters, the probes could provide in situ sampling of ozone, carbon dioxide, and other chemical constituents (Plate 1).

Plate 1 In addition to monitoring weather, the probes could provide in situ sampling of ozone, carbon-dioxide, and other chemical constituents

ENSCO is currently developing initial prototypes assembled with commercial-off-the-shelf components with the goal to demonstrate a prototype GEMS system by fall of 2006. The prototype system will feature a small number of functional GEMS probes that collect and disseminate meteorological data under relatively quiescent weather conditions. The prototype probes are expected to cost ~$100 per device with a form- factor that will be spherical or disk shaped at ~50 cm in diameter and weighing ~70 gm. Today's sensor technology can be integrated into such a low-cost, power, and mass suite to measure temperature, pressure, humidity, and wind velocity using micro global positioning systems with the same accuracy as current atmospheric observing platforms, such as weather balloons. A conceptual representation of GEMS probes illustrating form factor as well as one possible mode for deployment and communication are shown in the figure below.

Technological advancements over the next 10-15 years are expected to yield future generations of GEMS that cost about $1 per probe. In addition, GEMS are expected to achieve further reductions in mass and diameter to ~5gm and ~15cm, respectively. Such reductions in size and cost will be possible based on miniaturization/ integration of the sensors and electronics into the shell of the probe. Materials science will also likely play a prominent role, as carbon-nanotube reinforced polymers offer the potential to dramatically decrease shell thickness while also increasing shell strength. Bioinert or biodegradable electronics and shell materials could be incorporated into the probe design, thus making GEMS environmentally friendly.