Imec presents a MEMS energy harvester suitable for shock-induced energy harvesting in car tires

Dec 08, 2011
Harvesters with various dimensions. The shiny capacitor stack on top of the beam is visible through the glass package.

Imec and Holst Centre announce that they have made a micromachined harvester for vibration energy with a record output power of 489µW. Measurements and simulation show that the harvester is also suited for shock-induced energy harvesting in car tires, where it could power built-in sensors. In a tire, at 70km/h, the new device can deliver a constant 42µW, which is enough to power a simple wireless sensor node. These results, obtained within the research centre’s program for Micropower Generation and Storage, are presented at the 2011 IEEE International Electron Devices Meeting (IEDM) in Washington (December 7-9).

Imec’s innovative harvester consists of a cantilever with a piezoelectric layer sandwiched between metallic electrodes, forming a capacitor. At the tip of the cantilever a mass is attached, which translates the macroscopic vibration into a vertical movement – putting strain on the piezoelectric layer and generating a voltage across the capacitor. As piezoelectric material, AlN (aluminum nitride) was chosen. The harvesters are packaged with a 6-inch wafer scale vacuum packaging process. The micromachining production process is compatible with low-cost mass-production fabrication.

The harvester has a record output of 489µW when the vibrations closely match the ’ resonance vibration, which in this case is 1011Hz. Together with an automotive partner, imec also validated the use of the harvester for use in car tires. These submit the harvester to regular shocks, depending on the car’s speed and the characteristics and condition of the tire. Each shock will displace the mass, after which it will start to ring down at its natural resonance frequency. During this ring-down period, which depends on the quality factor Q of the harvester, part of the mechanical energy is harvested. It is shown that in this way, a constant power output as high as 42µW can be harvested at a speed of 70km/h.

Micromachined harvesters such as these are ideal devices to generate electricity from machines, engines and other industrial appliances which vibrate or undergo repetitive shocks. In these environments, they will power miniaturized autonomous sensor nodes, in situations where battery replacement is not sustainable or practical. Harvesters will allow sustainable monitoring on a massive scale. One example is Tire Pressure Monitoring Systems (TPMS) and its successors: a car tire with built-in sensors that monitor e.g. the tire integrity and pressure, the road condition, or the driving style.

Explore further: NERSC, Cray move forward with next-generation scientific computing

Related Stories

Good vibrations

Mar 23, 2010

(PhysOrg.com) -- Energy harvesting - using vibrations from the environment to produce electricity - has been around for over a decade, but Dr Stephen Burrow and his team in the Department of Aerospace Engineering at the University ...

Recommended for you

Japan eyes nuclear for a fifth of electricity supply

1 hour ago

A fifth of Japan's electricity supply should come from nuclear power generation, the country's industry ministry said Tuesday, despite widespread opposition in the aftermath of the Fukushima disaster.

Sunfire, Audi en route to synthetic fuel of future

1 hour ago

How are scientific minds doing in coming up with a synthetic fuel as a viable alternative to petroleum? For some engineers, this is a long-held dream they refuse to dismiss. A Dresden-based company, sunfire, ...

Yahoo unveils new online video series

3 hours ago

US Internet giant Yahoo said it was expanding its online offerings, unveiling 18 new video series with which it hopes to attract a larger audience and advertisers.

Apple's Mac is selling strong, iPad not so much

4 hours ago

Apple's iPhone was again the company's star in the first three months of the year. The tech giant sold 61 million iPhones, or 40 percent more than in the same period a year ago. That represented about two-thirds ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.