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Netværksopkoblede sensorer med ekstremt lavt energiforbrug

Netværksopkoblede sensorer med ekstremt lavt energiforbrug

I forbindelse med et såkaldt 'Lighthouse' projekt har Fraunhofer-forskere og partnere udviklet en ekstrem energieffektiv hardwareplatform til brug i netværksopkoblede sensorsystemer (in english).

The Internet of Things (IoT) is growing steadily. An enormous number of networked nodes collecting, evaluating and converging data in a network is therfore already necessary today. The problem: The energy consumption of the nodes is enormous.

According to a study by the International Energy Agency in 2013, the energy requirements of all networked devices worldwide corresponded to the total demand for electrical energy in Germany. Within the next few years, this need will almost double to 1140 terawatts per year, with networked IoT accounting for a significant share of this growth. For this reason, it is important that the sensors become more energy efficient.

So far, industry and research have not come up with a comprehensive solution: for each application, a single IoT hardware is developed that is more or less energy efficient. The Fraunhofer-Gesellschaft wants to change that: In its  'Towards Zero Power Electronics (ZEPOWEL)' lighthouse project, a hardware solution is to be developed that is both holistic and extremely energy-efficient. In a following step, networked sensors could even work with complete self-sufficiency.

Fraunhofer uses two levers: Firstly, the nodes themselves are to consume significantly less energy, and secondly, energy savings are to be achieved at the systemic level. This means that communication with other systems will also save energy.

- We want to create the technological platform for a comprehensive IoT application," explains Erik Jung, project team member at the Fraunhofer Institute for Reliability and Microintegration IZM.

The Fraunhofer Institutes want to solve the following challenges:

1. Highly efficient components for robust and secure communication
New technologies are being developed in the lighthouse project, such as an ultra-low-power wake-up receiver, which ensures that a sensor node does not have to transmit data continually, but rather 'awakens' at a certain threshold or through an authenticated request from outside.

The module developed in the project is expected to be 1000 times more efficient than existing standard radio solutions. The receiver responds only to authorized and cryptographically secured signals that are actually relevant for it. In this way, the sensor node can remain in standby mode with minimal power consumption and be activated immediately by the WakeUp receiver as necessary.

2. More accurate measurement with less energy
In addition, the project is aiming at a unique sensor innovation: an air quality sensor is intended to be coupled with a micro-pump. The pump will then serve as a measuring amplifier by greatly increasing the amount of supplied air. If this attempt is successful, the result will be a sensor that can be built with much less intrinsic sensitivity, while at the same time providing data that is far more accurate.

Whereas today’s sensors can deliver 5000 measurements at a power of 1250 microwatts per second, the developed sensor is expected to deliver twice as many readings per second with a power of less than 10 microwatts.

The sample sensor is intended to measure the particulate matter in cities. While measurements of particulate matter used to be extremely time-consuming and could therefore only be performed at a few nodes at the same time, the new technology is intended to enable a denser and more accurate measurement.

The intelligent networking of the nodes and the connection to common cloud platforms can be used to create a detailed model of fine particulate emissions in cities. The applications are numerous: for example, traffic flow control could be based on it, and navigation systems could adapt their routes to it independently.

3. Sensors supply themselves with electricity even more easily
Not only is the collection and transmitting of data to be optimized, but also the energy balance of the nodes themselves.

Therefore, a broadband harvester is to be developed, a kind of harvester for ambient energy. Its efficiency is quadrupled in comparison to the current state of the art: to harvest 100 microwatts of power from its environment, it only needs a quarter of the area, namely 5-by-5 square millimeters. The energy harvested in this way is stored in a newly developed thin-film battery, which is integrated directly on the hardware chip. This fully integrated approach of battery, harvester and energy converter is unique in the world.

An example makes clear how this can work: if you throw something on the ground, energy is generated with a bandwidth of a few hertz up to a few kilohertz. An absorber that only resonates at one hundred hertz can therefore only absorb little energy from the throwing. However, if a resonator is developed that can absorb energy over a wide frequency range, significantly more energy is harvested from the throwing.

4. Modular construction kit for every application

The ZEPOWEL lighthouse project has also set itself the goal of not developing any purely application-specific nodes, but instead a modular approach based on the plug and play principle.

- We offer a module for many applications: it’s a plug-in system, like with Lego blocks. Click – and it works, explains Erik Jung. The resulting platform consists of individual innovations created by the institutes which can be combined as desired. While a specific hardware solution has been created for each IoT application, a universal IoT hardware is being developed in this project. Depending on the application, the customer can then 'cherry pick' as he prefers.

5/4 2018
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