The complete electronic sensor, which weighs only 1.8 grams, is imbedded in the cube, and a 3D antenna is positioned around it. Photo credit: Muhammad Fahad Faroouqi
Atif Shamim and Christian Claudel, KAUST Assistant Professors of Electrical Engineering, work together on creating wireless sensor networks for "smart cities." It is technology Prof. Shamim describes as "game changing…It will change the way we do many things in our lives, moving us towards smarter living," he said.
In the "smart cities" of the future, electronic devices and objects will be "smart," with objects containing sensors that communicate with each other, fixed network nodes and central servers. These sensors are connected through the Internet of things (IOT), which enables them to share information. Intelligent systems at the central servers are then used to analyze and process the data from the sensors.
"The critical component for these processes is low-cost wireless sensing modules," explained Prof. Shamim. "Fixed sensor nodes are useful, but for these you need a lot of infrastructure, such as towers and assemblies. Our idea is that you would have some fixed sensors, but you would disperse many small, mobile sensors that communicate wirelessly to the fixed sensors, which then communicate all the received information to a central station for analysis."
The use of small, mobile sensors reduces the cost of the infrastructure tremendously, noted Prof. Shamim, and also enables information to be gathered from remote locations where it is difficult or impossible to mount fixed sensors, such as in forests or deserts.
Together, the research groups of Prof. Shamim and Prof. Claudel combined their respective talents and expertise to make progress in using wireless sensors for flood monitoring. This issue is of high importance to Saudi Arabia and cities such as Jeddah, which saw a 2009 catastrophic flood claim the lives of hundreds and cause considerable property damage.
"Classical sensing solutions, such as fixed wireless sensor networks or satellite imagery, are too expensive or too inaccurate to detect floods – and in particular flash floods – well," noted Prof. Claudel. "Instead, we tested the use of Unmanned Aerial Vehicles (UAVs) equipped with mobile, floatable, 3D printed microsensors and sensor delivery systems to sense and monitor flash flooding events."
This new system of mobile, floatable sensing, called Lagrangian sensing, "is very promising for large scale sensing, or on-demand sensing, as it requires minimal infrastructure," the researchers stated. Using this method, UAVs drop the small, disposable wireless sensors over an area to be monitored. The sensors float, so they are carried away by the water flow of the flood. As they move along in the water, they send signals to the UAVs. These signals map the extent of the flood, and this information is transmitted to a central, fixed station for processing. It can then be used to warn the public and other authorities about the extent of the flood.
"Prof. Claudel carries out the systems level design and implementation for the research project, and my group develops the actual physical sensors," said Prof. Shamim. "In that way, I believe we are a very good fit for collaboration."
Their collaboration produced a paper recently published in IEEE Transactions on Antennas & Propagation, entitled "An Inkjet-Printed Buoyant 3-D Lagrangian Sensor for Real-Time Flood Monitoring" (DOI: 10.1109/TAP.2014.2309957). KAUST has applied for patent protection for this and other related technologies.
One of the challenges Profs. Claudel and Shamim and their teams faced in the research work was designing the sensors. "We wanted to make them low-cost so they are basically disposable," explained Prof. Shamim. "We use inkjet printers to print electronics on paper and plastics, but in this case we used paper, as it is lightweight, 1/10th the cost of plastic, and is very suitable for inkjet printing. In addition, it is biodegradable and comes from a renewable resource."
The researchers produced a small paper cube with a size of 13 mm x 13 mm x 13 mm. The complete electronic sensor, which weighs only 1.8 grams, is imbedded in the cube, and a 3D antenna is positioned around it, enabling the cube to give a signal in any direction it is moving (or floating).
"Because we were working on a flood monitoring application, we had to optimize the sensor to work in water as well as in air," Prof. Shamim noted. "We were skeptical about its performance in water, so we sealed it with a special glue. We then produced a cube that is very small, lightweight, floats in water, and is electrically sealed. It works very well in water and radiates up to 50 meters in all directions. The performance was better than we expected."
The technology has many other possible applications: "You could integrate sensors for ammonia, sulfur, carbon monoxide, humidity, or temperature into the cube," said Prof. Shamim. "This would allow for detection of poisonous gases and other environmental conditions, which would be especially helpful in industrial settings and in remote locations, such as during forest fire events."
Profs. Shamim and Claudel want to integrate their low-cost, printable, and disposable microsensor technology into the day-to-day lives of everyday people. Not only would the technology enable greater safety for individuals during catastrophic events such as floods, but it could also assist in locating cars in busy parking lots, tracking expired foods in supermarkets, and in creating smart houses, where household appliances and electronic lock systems "talk" to each other to make sure they are in proper working order.
"I believe this technology will change the way people live, shop, and monitor things," said Prof. Shamim. "We will have better living, from our homes to our offices to our industries – and that is a benefit for all."
- By Caitlin Clark, KAUST News