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Sensing Without Consuming Power: Groundbreaking Work Showcased in Nature Nanotechnology

September 11, 2017

A team led by Northeastern University Associate Professor of Electrical and Computer Engineering Matteo Rinaldi recently unveiled its groundbreaking work on zero-power infrared digitizer technology -- findings that have compelling implications for our increasingly interconnected world.

Rinaldi and researchers Zhenyun Qian, Sungho Kang, Vageeswar Rajaram, Cristian Cassella and Nicol E. McGruer share their discoveries in the September 11, 2017 edition of the prestigious scientific journal Nature Nanotechnology. View the published manuscript.

The team’s work addresses a key challenge posed by the Internet of Things revolution: how to power and maintain the rapidly increasing connected devices worldwide, expected to grow from 15 billion today to 50-200 billion by 2020. Supporting all these devices requires sensors and actuators with dimensions and power consumption significantly smaller than current versions. State-of-the-art sensors consume power continuously to monitor the environment, even when there is no relevant information present. Constant power consumption limits the sensor’s lifetime and causes high maintenance cost, particularly for networks of “unattended sensors” that detect infrequent but time-critical events such as perimeter intrusions, wildfires, earthquakes or chemical warfare threats.

In the newly published findings, Rinaldi and his team present their solution to this issue: a zero-power infrared digitizer prototype that allows sensors to, in effect, remain “asleep”—with zero-power consumption—until awakened when useful information is available or a critical event occurs. With such capability, unattended sensors can operate with a nearly unlimited lifetime.

Enhancing the quality of life 

“To break the paradigm of wasting energy in standby, we really need to think out-of-the-box and devise new kinds of completely passive digitizing sensor microsystems that can detect and discriminate events of interest by exploiting only the energy contained in their specific physical signatures,” says Rinaldi.

“Among different physical signals, the intensity and spectral content of light emitted by targets of interest, such as a vehicle or a human body, can be one of the most effective and specific triggering signatures,” explains Qian, the lead author on the paper, “so we came up with the idea of building micromechanical relays that are selectively triggered by specific wavelengths of infrared light without the need of any electrical power.”

“Our findings can ultimately enhance quality of life,” concludes Rinaldi. “The capability to consume power only when useful information is present has a groundbreaking impact on the proliferation of the Internet of Things where physical and virtual objects in different environments are connected through the exploitation of sensing and wireless communication capabilities with the intent of making the everyday life safer, simpler and more efficient.”

Originally from Rome, Italy, Rinaldi joined Northeastern’s Department of Electrical and Computer Engineering in January 2012. His research and scholarship interests focus on understanding and exploiting the fundamental properties of micro/nanomechanical structures and advanced nanomaterials to engineer new classes of micro and nanoelectromechanical systems (M/NEMS) with unique and enabling features that can be used in a wide range of application areas such as the Internet of Things, wireless communications, homeland security, environmental monitoring, health care and aerospace. The author of more than 80 publications, Rinaldi also holds five patents in the field of micro/nano mechanical devices.

See other coverage: DARPA, TechCrunch, International Business Times, IEEE Spectrum

Source: News @ Northeastern

When stationed in dangerous, rural areas, the last thing soldiers should worry about is replacing a dead battery. That’s one reason why the Defense Advanced Research Projects Agency, or DARPA, is interested in developing devices that use virtually no power at all.

DARPA has a vision to employ a network of miniaturized sensors in remote locations. But the cost of maintenance would be tremendous, unless the sensors could last many years on very little power.

Matteo Rinaldi, associate professor of electrical and computer engineering at Northeastern, has just the answer. He was awarded a grant to build a new type of sensor that consumes no power whatsoever in standby mode. When the sensor recognizes a specific infrared wavelength signature, it uses the tiny amount of power contained in the infrared radiation to wake itself up. Then it triggers an “output wake-up bit,” or a voltage signal, that could alert soldiers or others to an event of interest, such as an approaching vehicle.

Rinaldi’s sensor design is described in a new paper, published last week in Nature Nanotechnology. It consists of a tiny, micromechanical switch that controls the connection to a battery. Only when the switch is activated by the infrared radiation does it move to close the gap between itself and its battery, triggering the wake-up signal.

The switch can be designed to detect very specific events. For example, the exhaust plume of a car has a certain signature of infrared radiation. To pick up on that signature, Rinaldi and his team patterned a correlating arrangement of tiny patches of gold on the surface of the switch. When the patches are exposed to the correlated infrared radiation signature, they absorb its energy, which heats up the device.

The switch contacts are supported by beams made out of a two-material stack. “When the temperature of this structure increases, one material expands more than the other, and therefore the beams bend,” Rinaldi explains. That bending allows the switch to make contact with the battery and spit out a signal.

To pick up on a specific infrared signature, Rinaldi arranged a correlating pattern of tiny patches of gold on the surface of the switch. When the patches sense the heat from the infrared radiation, the switch moves to close the gap between itself and the battery, triggering a signal. Photo by Adam Glanzman/Northeastern University
To pick up on a specific infrared signature, Rinaldi arranged
a correlating pattern of tiny patches of gold on the surface
of the switch. When the patches sense the heat from the
infrared radiation, the switch moves to close the gap
between itself and the battery, triggering a signal.
Photo by Adam Glanzman/Northeastern University

Current sensors are not “smart” enough to detect an event of interest while dormant. They require a constant power source. Rinaldi’s sensor would allow DARPA and other organizations to deploy large networks of sensors that continuously monitor the environment, without consuming any power in standby mode. This could make warzones or other hazardous locations much safer, and the sensors would be much less expensive to maintain.

The sensor design can also be tweaked to recognize other signals. For example, they could be made to detect certain chemicals, specific wireless radio frequency signals, or magnetic fields.

Rinaldi imagines sensors embedded all over cities, to make everything—from buildings to transportation systems—smarter.

“If we have all these sensors embedded in the infrastructure of the city, that would increase awareness, making everyday life safer and more efficient,” Rinaldi said. “That’s the vision.”