While trying to create a circuit that detects whether water is flowing through a pipe by measuring the vibration with a piezoelectric sensor, just to see what happens I taped the sensor around my finger and – to my surprise – got values that were a very noise-free representation of my heart rate!
Measuring Heart Rate With A Piezo – [Link]
by Stephen Evanczuk @ digikey.com:
Pulse-energy-harvesting applications convert bursts of energy to sufficient power for operating simple circuits such as wireless switches, wireless data loggers, remote controls, and the like. To build these designs, engineers can draw on a wide variety of available ultra-low-power ICs and energy transducers from manufacturers including EnOcean, Linear Technology, Linx Technologies, Maxim Integrated, Measurement Specialties, Microchip Technology, Mide Technology, ROHM Semiconductor, Schurter, Silicon Labs, and Texas Instruments, among others.
Powering Circuits through Pulse-Energy Harvesting – [Link]
by Darren Quick @ gizmag.com:
Researchers from Columbia University and the Georgia Institute of Technology are laying claim to having observed piezoelectricity in an atomically thin material for the first time. The effect was demonstrated in the world’s thinnest electric generator made from a two-dimensional molybdenum disulfide (MoS2) material, which had previously been predicted to exhibit such properties.
Two-dimensional piezoelectric material forms basis of world’s thinnest electric generator – [Link]
by University of Twente:
Researchers from the University of Twente MESA+ research institute, together with the company SolMateS, have developed a new type of transistor to reduce the power consumption of microchips. The basic element of modern electronics, namely the transistor, suffers from significant current leakage. By enveloping a transistor with a shell of piezoelectric material, which distorts when voltage is applied, researchers were able to reduce this leakage by a factor of five (compared to a transistor without this material). An article presenting the prototype of the transistor appears in the June issue of IEEE Transactions on Electron Devices, an authoritative scientific journal in the field of transistor research.
Prototype of new transistor for lower power consumption – [Link]
by Francesc Casanellas:
This design was done to get a sealed keypad for very wet environments (in my particular case, showers for swimming pools). The keypad needed to be able to detect slight pressure on a stainless steel plate 0.4mm thick. Apart from water protection, the solution offers an esthetical finish, as the user side is absolutely flat, with nothing visible other than the silkscreened print. Another advantage of this type of keypad is that it is vandal-proof. The core of the sensor is a piezoelectric disc, the type normally used as a buzzer. I chose the Murata 7BB-35-3. With 35mm of external diameter, it allows a sensitive area of about 20mm diameter.
Water & vandal-proof keypad uses piezoelectric disc as sensor and buzzer – [Link]
Researchers from several institutions in the U.S. and one from China have together developed a piezoelectric device that when implanted in the body onto a constantly moving organ is able to produce enough electricity to run a pacemaker or other implantable device. In their paper published in Proceedings of the National Academy of Sciences, the team describes the nature of their device and how it might be used in the future.
Currently, when the battery inside a device such as a pacemaker runs out of power, patients must undergo surgery to have it replaced. Several devices that take advantage of the body’s natural parts have been devised to allow for the creation of electricity internally so that implantable devices can run for a lifetime, preventing the need for additional surgery. Most such devices have been too small to actually charge a real device, however, as they are very much still in the research stage. In this new effort, the research team takes the idea further by creating miniature power plants that are large enough to power real implantable devices.
Team builds implantable piezoelectric nanoribbon devices strong enough to power pacemaker – [Link]
Imec and Holst Centre announce that they have made a micromachined harvester for vibration energy with a record output power of 489 µW. 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 45 mph, the new device can deliver a constant 42 µW, 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. [via]
Car tires harvest energy – [Link]
Stephen Evanczuk writes:
Micro-harvesting, or energy scavenging, relies on extracting power from minute but pervasive sources of ambient energy such as light, heat, RF, or vibration. With piezoelectric devices, energy from vibration can supply low-power applications, such as wireless sensors that are difficult to reach and maintain, for equipment or structural monitoring. By following a few key design considerations, engineers can build applications powered by piezoelectric transducers from Parallax, Measurement Specialties/Schaevitz, and Mide Technology and power management devices from Linear Technology.
Compared to other micro-harvesting energy sources, vibration and motion are relatively robust sources of ambient power (Figure 1). Placed on motors, for example, vibration-powered sensors can harvest power precisely when it is needed during motor operation. In a practical application, the piezoelectric transducer would likely be used to charge a high efficiency storage device rather than provide power directly to application circuits.
Energy Scavenging with Piezoelectric Transducers – [Link]
The same piezoelectric effect that ignites your gas grill with the push of a button could one day power sensors in your body via the respiration in your nose.
Writing in the September issue of the journal Energy and Environmental Science, Materials Science and Engineering Assistant Professor Xudong Wang, postdoctoral Researcher Chengliang Sun and graduate student Jian Shi report creating a plastic microbelt that vibrates when passed by low-speed airflow such as human respiration.
In certain materials, such as the polyvinylidene fluoride (PVDF) used by Wang’s team, an electric charge accumulates in response to applied mechanical stress. This is known as the piezoelectric effect. The researchers engineered PVDF to generate sufficient electrical energy from respiration to operate small electronic devices. [via]
Electricity from the nose – [Link]