Podcasts about piezoelectric

This week's EYE ON NPI is trendy and buzzy, it's Boréas Technologies' BOS1931 High-Efficiency Piezo Driver (https://www.digikey.com/en/product-highlight/b/boreas/bos1931-high-efficiency-piezo-driver). This chip is a compact way to add powerful high-voltage piezo drive to any product, combining three chips: power supply, waveform generator and driver. With a complete I2C/I3C interface that you can connect to any microcontroller/processor it's the most advanced all-in-one piezo driver we've seen! Piezo (https://en.wikipedia.org/wiki/Piezoelectricity) discs are multi-use devices that convert mechanical movement to electrical signal, and vice-versa. They're most often seen as electrical-to-mechanical converters such as piezo beepers (https://en.wikipedia.org/wiki/Piezoelectric_speaker) where an AC signal, usually 3 to 6V peak-to-peak square wave, is applied across the disk. The frequency of the wave is translated into a sound frequency. It doesn't have the same fidelity as a magnetic speaker but its much thinner, less expensive for the component and driving circuitry, and for 2 to 4 KHz beeps it's just fine. Piezos can also be used the opposite way, where mechanical stress on the crystal is translated into an electrical signal. In this way it can be used as a switch or force sensor (https://en.wikipedia.org/wiki/Piezoelectric_sensor), again usually a few microamperes' worth of current is generated. For these basic uses, your standard microcontroller pin, or at best an H-Bridge will work just fine: you can drive piezo's differentially to get more Vpp across the disc but essentially we're still talking about only a few Volts. There are some times when you want to make a piezo really 'loud' - that is, putting 100+ Volts across the crystal to generate a big mechanical response. This is often not for audible use cases, after all if you wanted to do that you'd just use a magnetic speaker (https://www.adafruit.com/product/1732) that can get to many many Watts of output efficiently. FYI there's two variants of the chip: the BOS1931 (https://www.digikey.com/short/w9tz9tbj) and the BOS1921 (https://www.digikey.com/short/nnb0r29r). The '31 can only do piezo driving. The '21 can do sensing as well as driving, so it can be used for force-feedback products. In this particular EYE ON NPI we'll just be chatting about the driving capabilities of both. So, while we can do basic sensing/beeping with a few Volts - when we want to have significant motion for blasting sonar or moving fluid around we can only increase the movement by increasing the peak-to-peak voltage. Each piezo you buy will have a voltage rating - and you will need a boost converter to generate that peak-to-peak. For the BOS19 series of chips, you can get +-95V so 190Vpp max, which will drive any piezo you find, and you only need 3~5V input thanks to a built-in DC/DC boost converter. Boréas didn't stop there. Not only do you get a booster, but also a full waveform manager with I2C/I3C control. You can can fill up a FIFO buffer with waveform bytes to generate different shapes. There's a sine generator you can control with an envelope creator. Or, you can piece together waveform shapes for different pump/haptic behavior, giving you the customizability of a byte-wise waveform generator with the simplicity of a sine generator. They even have a Haptics Studio' to help you craft the waveform you want (https://www.boreas.ca/pages/haptic-studio). The BOS1931 (https://www.digikey.com/short/w9tz9tbj) and the BOS1921 (https://www.digikey.com/short/nnb0r29r) come in two packages: an easy-to-layout-and-solder QFN and a tiny-and-advanced BGA. Both have the same core so just pick whether you need simplicity or small size. Since its a pretty serious boost converter and driver - the piezo connects directly to the output pins - you'll need to watch your layout. Check the datasheet for their recommended setup to make sure you don't have excessive power loss or EMI. IF you want to get started quickly, the BOS1921-KIT-B01 (https://www.digikey.com/short/v9hn8mcd) evaluation board will let you use their configuration software to quickly determine how your piezo actuator or sensor response to the waveform generator and booster before you start laying out the components on a prototype PCB. If you have some serious piezo-ing you need to get moving, the Boréas Technologies' BOS1931 High-Efficiency Piezo Driver (https://www.digikey.com/short/w9tz9tbj) can do everything from voltage generation, waveform shaping, and differential driving. And best of all it's in stock right now at Digi-Key for immediate shipment! Order today and DigiKey will pick and pack your order in an instant so that you can be vibin' with your fancy new piezo controller by tomorrow afternoon.

With input from Lewis Research Center, now NASA Glenn, the Impax line of force measurement products was born.

A NASA spinoff involving piezoelectric technology developed decades ago is still in use in sports and by Olympic trainers today.

May 1, 2024: From Crystals to Currents: The Piezoelectric Effect

I am happy to announce that longtime friend of the show Alissa Fitzgerald is my guest this week! Alissa and I discuss MEMS product development, the details of AMFitzgerald's unique innovation process, and why recent developments in thin-film PZT MEMS chips will change the future of MEMS applications.  

In this podcast episode, MRS Bulletin's Laura Leay interviews Hamideh Khanbareh and Vlad Jarkov of the University of Bath in the UK about an application they introduced for using piezoelectric materials in tissue engineering. The researchers fabricated a composite by combining polydimethylsiloxane with a piezoelectric material of potassium-sodium-niobate that is compatible with cell lines similar to neurons. They then studied how the composite material would interact with neural stem cells. They found that the piezolectrically activated composites allowed the cells to spread across the surface of the material and saw an increase in the amount of neurons. Usually the use of piezoelectric materials in tissue engineering requires mechanical stimulation from either movement of the body or the application of ultrasound. In this research, no additional mechanical stimulation was required. This work was published in a recent issue of Advanced Engineering Materials. 

Nothing brings people together like catastrophe. Is it wrong to wish for it all to come crashing down to have our own reset? What are the elite preparing for? Why do they need deep underground shelters? How do we create a compelling future that makes all of humanity excited to participate? We have forgotten what it means to be human. Impermanence has become normal. Humans together create a Divine Will Array sending frequencies out to the universe and to those around us. Flow form is the natural state of humanity but first we must sense our permanence in the world. Polarity Therapy follows the yin(negative = inward) and yang(positive = outward) electrical currents that our bodies pulsate. Whether there's too much or too little charge, our circuit finds the harmony as the ground holds neutral. Adjusting muscle fascia as to release the memory of trauma is incorporated so the Piezoelectric capacity of our skeletal system is invoked. When our ‘Body Electric' is coherent, life becomes more enjoyable. Topher Gardner is a former professional athlete, field goal kicker, turned yogi. Traded worldly ambition towards spiritual enlightenment which brought him to being a dome builder in Costa Rica. Grounded in Polarity therapy and dirt baggin' (Super Adobe) he sculpts body's and houses. TopherHQ.com @Biocharisma on Instagram Get your Aquacure! Use coupon code: FREEMAN for 5% off! Aquacure AC50 The AquaCure® (Model AC50) is the MOST ADVANCED and user-friendly Hydrogen Rich Water and HydrOxy for Health machine. Listen to George Wiseman on The Free Zone https://eagle-research.life/ The Free Zone with Freeman Fly - Saturday 8pm EST FreemanTV.com Watch Freeman's videos on Rokfin Follow me on Twitter @freemantv Associate Producer: Steve Mercer Send comments and guest suggestions to producersteve@freemantv.com

The Power of Piezoelectric Crystals, Meditation, and Memory Techniques In today's podcast episode, we delve into the fascinating world of piezoelectric crystals, meditation, and memory techniques. Piezoelectric crystals are a type of crystal that has the ability to generate an electric charge when subjected to mechanical stress. These crystals have a wide range of applications, including in electronic devices, medical devices, and even jewelry. Meditation is a practice that involves focusing your attention on the present moment and letting go of distractions. It has been shown to have a number of benefits for both physical and mental health, including reducing stress, improving sleep, and boosting creativity. Mnemonics are memory techniques that can help you to learn and remember information more effectively. They work by using associations, images, and other creative methods to encode information into your memory. In this episode, we will explore the following: The science behind piezoelectric crystals and their potential benefits for meditation and memory Real-life stories of people who have used piezoelectric crystals to improve their meditation and memory practices Simple and effective mnemonic techniques that you can use to learn and remember information Whether you are a seasoned meditation person,or a complete beginner, this episode is packed with valuable information that can help you to improve your focus, memory, and overall well-being. So grab your headphones and get ready to learn about the power of piezoelectric crystals, meditation, and memory techniques. More fun with Mr Magoo as Scrooge too! #piezoelectriccrystals,#meditation,#mnemonics,#memorytechniques,#focus, piezoelectric crystals#wellbeing Binaural beats are a type of auditory illusion that occurs when two slightly different frequencies are played in each ear. Binaural beats have been shown to have a number of benefits for the mind and body, including reducing stress, improving sleep, and enhancing creativity. #binauralbeat #meditation #relax #binaural #binauralsound #focus #sound #mindfulness #binauralrecording #mindhz #highperformance #treino #academia #gym #mind #mente #training #altaperformance #app #foco #o #medita #sonsbinaurais #relaxmusic #anxiety #stress #binauralbeats #meditac #relaxingmusic #goodvibes --- Send in a voice message: https://podcasters.spotify.com/pod/show/bhsales/message

If you're looking for a new scaler, temping, or working in multiple offices, it helps to know the differences—and the similarities—between piezoelectric and magnetostrictive ultrasonic scalers. by Amy Lemons, BSDH, RDH   Read Article HERE: https://www.rdhmag.com/patient-care/power-instrumentation/article/14298248/piezoelectric-vs-magnetostrictive-ultrasonic-scaler-whats-the-difference 

Piezoelectric actuators embedded in commercial foam arches increase tactile awareness and could help seniors improve their balance.

Get a monthly subscription to access premium episodes!'Easy Physics' is a podcast that delves into the bizarre and fascinating world of this amazing science. Join us as we use humor and plain language to explore many fundamental principles, and learn about each one of them in a few minutes. From particles that exist in multiple places at once to the immensity of the cosmos, we'll take a lighthearted look at the most mind-bending concepts in physics. Hosted on Acast. See acast.com/privacy for more information.

You all know how much I love Superhero Movies! Piezoelectric Effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress. The word Piezoelectric is derived from the Greek piezein, which means to squeeze or press, and piezo, which is Greek for “push”. Do you ever feel this way? Pushed around, pressed down on and like life is being sqeezed out of you? Have a listen! I think this can help. Also review Episodes 2 and 51 . What is that H before the Episode Number? Learn more about the C.R.U.S.H. Framework & the C.R.U.S.H. Course at https://www.LindaWinegar.com Find more strength and validation at LindaWinegar.com or on Instagram https://www.instagram.com/lindaswinegar Text me 561-316-8883 to get the 100 Battle Cries List PDF or if you would love to learn about the ways the adversary is showing up in your life, I have a PDF for that too.

In the field of ceramics, glazes are usually applied on the raw tile by means of spray “analogical” systems (airless application system). Nevertheless, recently some new application machines have appeared on the market.They cannot be defined as completely digital but they cannot even be comparable to traditional analogue techniques. How do they work?What kind of features should the glaze have to be properly applied?

  Vidcast:  https://youtu.be/pHgQ9JsvwDo   Here are the latest cutting edge medical and healthcare discoveries this 3rd Week of August, 2022.  Many of discoveries will become the therapies of tomorrow.   MIT bioengineers have developed self-powered wearable wireless sensors capable of transmitting data about pulse rate, sweat composition, and ultraviolet radiation exposure.  What's unique about these wearables is that they perform this monitoring without embedded Bluetooth chips or batteries.  The ultrathin sensing film is composed of gallium nitride with 2-way piezoelectric properties allowing it to both sense underlying skin changes and complete wireless transmission of the collected data when paired with a conducting layer of gold.   https://www.science.org/doi/10.1126/science.abn7325     The placenta is known as the “engine of pregnancy” since it provides oxygen and vital nutrients to the developing fetus.  University of Pennsylvania researchers now report a unique method for monitoring placental function and blood flow utilizing a unique combination of ultrasound and optical spectroscopy.  Light and sound waves are simultaneously directed through the pregnant woman's abdomen, and the reflected light is amplified and background noise removed to permit quantification of placental oxygen levels.  This precise placental monitoring permits better management of hight risk pregnancies.   https://www.nature.com/articles/s41551-022-00913-2       A newly synthesized peptide called A1R-CT is capable of suppressing seizures when introduced into the body in a nasal spray.  Neurologic researchers at the University of Alabama-Birmingham have shown that this protein facilitates activation of the A1 receptor on neurons that squelches excess electrical activity and seizures.  These epileptic seizures that commonly accompany strokes, traumatic brain injuries, and neurodegenerative diseases including Alzheimer's are poorly controlled by conventional agents in some 40% of patients.  The A1R-CT nasal spray may help solve this problem.   https://insight.jci.org/articles/view/155002     And finally…..More news about uniquely therapeutic nasal sprays.  Looking to create nasal lining immunity where the CoVid virus first enters the body,  MIT researchers have successfully fused CoVid receptor binding domain spike antigens with an albumin-binding polymer lipid that opens a portal into nasal linings so that the CoVid proteins can effectively trigger a vigorous, local immune response against themselves.  The hope is that effective nasal IgA antibody immunity will offer better protection against the latest group of Omicron subvariants including BA.5. https://www.science.org/doi/10.1126/scitranslmed.abn1413     There you have the cutting edge medical and healthcare discoveries this 3rd Week of August, 2022.    #wearables #piezoelectric #placenta #ultrasound #spectroscopy #seizures #a1rct #CoVid #nasalvaccine  

The Curie brothers discovered a class of materials that, with an asymmetrical crystal structure, could produce an electric potential upon mechanical deformation. These piezoelectric materials are now widely used in the medical, naval, and space industries. Before we introduce our guest, check out our free professional development guide for materials scientists and engineers! Today's guest is Dr. Susan Trolier-McKinstry. She is a Professor of Materials Science and Engineering at Penn State, where she is the Director of The Center for Dielectrics and Piezoelectrics as well as the Center for Three Dimensional Ferroelectric Microelectronics. In this episode, she dives into the working principles and applications of piezoelectric materials. In this conversation, we discuss the following topics: What are piezoelectric materials The asymmetric crystal structure of piezoelectronics The intersection between ultrasound and sonar technology Correcting the lenses of telescopes Miniaturized ultrasound  Piezoelectric materials used in computing devices Learn more about our MSE Career Development Online Course, which includes more industry-specific information and advice.  Also, check out our MSE-themed merchandise if you want to support us or simply show off your love of materials science! Thank you Joao Morgado for editing this episode! Join our Discord community! You can meet other passionate materials scientists and engineers from around the world, discuss the latest breakthroughs in MSE, share materials-related memes, and get career advice from experts in the field. For shorter segments and full video podcasts, subscribe to our channel on YouTube. For bloopers, audiograms, and interesting materials science articles, follow us on Instagram, LinkedIn, and Twitter. Feel free to message us on our social media platforms if you have any feedback or recommendations for future episodes, or email us directly at itsamaterialworldpodcast@gmail.com. Finally, reach out to David Yeh and Punith Upadhya on LinkedIn if you'd like to chat about the latest breakthroughs in MSE! Disclaimer: Any opinions expressed by either guests or hosts in this show are their own, and do not represent the opinions of the companies or organizations for which they are affiliated.  

https://medicienterprises.com/2021/10/16/show-543/

Ziggy Dan is the Man! The nub phenomenon is a real mystery. Are they an ancient language like a morse code like The Stone-Nub Language @TwistDead1 suggests? A kind of Braille for Giants? Or Ziggy's personal favorite an ancient shared stone Mason's code? My favorite is the Piezoelectric qualities that they might have provided. There is the faceting notches theory or the one that has to be wrong “for lifting”! Maybe they are something we haven't touched on at all, we really do not know. Join in on the nub club of people from around the world and see if you can figure out why there are seemingly random little nubs all over the globe on ancient ruins! This one might be nice to look at the youtube because I put a lot of pictures in the video! Find Ziggy on Youtube https://www.youtube.com/channel/UC6C9... Twitter: ziggydan @ziggydan1 And if you want to hit Nikki up: Nikkianajones@protonmail.com Telegram channel: https://t.me/nikkiana_jones​​​​​​​​​​ IG: nikkiana_jones Twitter: @LivingExtraord1 Youtube https://www.youtube.com/watch?v=p6vqKmvVDm8&t=2s --- Send in a voice message: https://anchor.fm/nikkianajones/message Support this podcast: https://anchor.fm/nikkianajones/support

Take a few seconds to leave us a review. It really helps! https://apple.co/2RIsbZ2 if you do it and send us proof, we'll give you a shoutout on the show.  (0:42) - Injectable Microchips:Researchers at Columbia University have developed a microchip the size of a grain of salt that can be injected into a patient and act as a wireless temperature sensor. The chip is powered by and communicates to a standard ultrasound probe from outside the body.  (9:00) - 2D Transistors:Moore's law has dictated the progress of computational power for the past few decades but lately, it seems like we've hit the physical limit of transistor development. There's now an international effort led by MIT and UC Berkeley to explore 2D transistors which could pave the way for keeping up with Moore's Law again.  (17:10) - AI For Spacecraft Diagnosis:NASA Pathways intern Evanna Gizzi has been working on Research in Artificial Intelligence for Spacecraft Resilience (RAISR) which aims to autonomously detect the root cause of spacecraft failures. RAISR is like an AI engineer that lives in the brain of a spacecraft to identify and remedy spacecraft failures.

Welcome to the History of Computing Podcast, where we explore the history of information technology. Because understanding the past prepares us to innovate of the future! Todays episode is is on the microphone. Now you might say “wait, that's not a computer-thing. But given that every computer made in the past decade has one, including your phone, I would beg to differ. Also, every time I record one of these episodes, I seem to get a little better with wielding the instruments, which has led me to spend way more time than is probably appropriate learning about them. So what exactly is a microphone? Well, it's a simple device that converts mechanical waves of energy into electrical waves of energy. Microphones have a diaphragm, much as we humans do and that diaphragm mirrors the sound waves it picks up. So where did these microphones come from? Well, Robert Hooke got the credit for hooking a string to a cup in 1665 and suddenly humans could push sound over distances. Then in 1827 Charles Wheatstone, who invented the telegraph put the word microphone into our vernacular. 1861 rolls around and Johan Philipp Reis build the Reis telephone, which electrified the microphone using a metallic strip that was attached to a vibrating membrane. When a little current was passed through it, it reproduced sound far away. Think of this as more of using electricity to amplify the effects of the string on the cup. But critically, sound had been turned into signal. In 1876, Emile Berliner built a modern microphone while working on the gramophone. He was working with Thomas Edison at the time and would go on to sell the patent for the Microphone to The Bell Telephone Company. Now, Alexander Graham Bell had designed a telephone transmitter in 1876 but ended up in a patent dispute with David Edward Hughes. And as he did with many a great idea, Thomas Edison made the first practical microphone in 1886. This was a carbon microphone that would go on to be used for almost a hundred years. It could produce sound but it kinda' sucked for music. It was used in the first radio broadcast in New York in 1910. The name comes from the cranes of carbon that are packed between two metal plates. Edison would end up introducing the diaphragm and the carbon button microphone would become the standard. That microphone though, often still had a built0-in amp, strengthening the voltage that was the signal sound had been converted to. 1915 rolls around and we get the vacuum tube amplifier. And in 1916, E.C. Wente of Bell Laboratories designed the condenser microphone. This still used two plates, but each had an electrical charge and when the sound vibrations moved the plates, the signal was electronically amplified. Georg Neumann then had the idea to use gold plated PVC and design the mic such that as sound reached the back of the microphone it would be cancelled, resulting in a cardioid pattern, making it the first cardioid microphone and an ancestor to the microphone I'm using right now. In the meantime, other advancements were coming. Electromagnets made it possible to add moving coils and ribbons and Wente and A.C. Thuras would then invent the dynamic, or moving-coil microphone in 1931. This was much more of an omnidirectional pattern and It wasn't until 1959 that the Unidyne III became the first mic to pull in sound from the top of the mic, which would change the shape and look of the microphone forever. Then in 1964 Bell Labs brought us the electrostatic transducer mic and the microphone exploded with over a billion of these built every year. Then Sennheiser gave us clip-on microphones in the 80s, calling their system the Mikroport and releasing it through Telefunken. No, Bootsie Collins was not a member of Telefunken. He'd been touring with James Brown for awhile ad by then was with the Parliament Funkadelic. Funk made a lot of use of all these innovations in sound though. So I see why you might be confused. Other than the fact that all of this was leading us up to a point of being able to use microphones in computers, where's the connection? Well, remember Bell Labs? In 1962 they invented the electret microphone. Here the electrically biased diaphragms have a capacitor that changes with the vibrations of sound waves. Robert Noyce had given us the integrated circuit in 1959 and of microphones couldn't escape the upcoming Moore's law, as every electronics industry started looking for applications. Honeywell came along with silicon pressure sensors, and by 65 Harvey Nathanson gave us a resonant-gated transistors. That would be put on a Monolithic chip by 66 and through the 70s micro sensors were developed to isolate every imaginable environmental parameter, including sound. At this point, computers were still big hulking things. But computers and sound had been working their way into the world for a couple of decades. The technologies would evolve into one another at some point obviously. In 1951, Geoff Hill pushed pules to a speaker using the Australian CSIRAC and Max Mathews at Bell Labs had been doing sound generation on an IBM 704 using the MUSIC program, which went a step further and actually created digital audio using PCM, or Pulse-Code Modulation. The concept of sending multiplexed signals over a wire had started with the telegraph back in the 1870s but the facsimile, or fax machine, used it as far back as 1920. But the science and the math wasn't explaining it all to allow for the computer to handle the rules required. It was Bernard Oliver and Claude Shannon that really put PCM on the map. We've mentioned Claude Shannon on the podcast before. He met Alan Turing in 43 and went on to write crazy papers like A Mathematical Theory of Cryptography, Communication Theory of Secrecy Systems, and A Mathematical Theory of Communications. And he helped birth the field of information theory. When the math nerds showed up, microphones got way cooler. By the way, he liked to juggle on a unicycle. I would too if I could. They documented that you could convert audio to digital by sampling audio and modulation would be mapping the audio on a sine wave at regular intervals. This analog-to-digital converter could then be printed on a chip that would output encoded digital data that would live on storage. Demodulate that with a digital to analog converter, apply an amplification, and you have the paradigm for computer sound. There's way more, like anti-aliasing and reconstruction filters, but someone will always think you're over-simplifying. So the evolutions came, giving us multi-track stereo casettes, the fax machines and eventually getting to the point that this recording will get exported into a 16-bit PCM wave file. PCM would end up evolving to LPCM, or Linear pulse-control modulation and be used in CDs, DVDs, and Blu-ray's. Oh and lossleslly compressed to mp3, mpeg4, etc. By the 50s, MIT hackers would start producing sound and even use the computer to emit the same sounds Captain Crunch discovered the tone for, so they could make free phone calls. They used a lot of paper tape then, but with magnetic tape and then hard drives, computers would become more and more active in audio. By 61 John Kelly Jr and Carol Lockbaum made an IBM 7094 mainframe sing Daisy Bell. Arthur C. Clarke happened to see it and that made it into 2001: A Space Odyssey. Remember hearing it sing that when it was getting taken apart? But the digital era of sound recording is marked as starting with the explosion of Sony in the 1970s. Moore's Law, they got smaller, faster, and cheaper and by the 2000s microelectromechanical microphones web mainstream, which are what are built into laptops, cell phones, and headsets. You see, by then it was all on a single chip. Or even shared a chip. These are still mostly omnidirectional. But in modern headphones, like Apple AirPods then you're using dual beam forming microphones. Beamforming uses multiple sensor arrays to extract sounds based on a whole lot of math; the confluence of machine learning and the microphone. You see, humans have known to do many of these things for centuries. We hooked a cup to a wire and sound came out the other side. We electrified it. We then started going from engineering to pure science. We then analyzed it with all the math so we better understood the rules. And that last step is when it's time to start writing software. Or sometimes it's controlling things with software that gives us the necessary understanding to make the next innovative leap. The invention of the microphone doesn't really belong to one person. Hook, Wheatstone, Reis, Alexander Graham Bell, Thomas Edison, Wente, Thuras, Shannon, Hill, Matthews, and many, many more had a hand in putting that crappy mic in your laptop, the really good mic in your cell phone, and the stupidly good mic in your headphones. Some are even starting to move over to Piezoelectric. But I think I'll save that for another episode. The microphone is a great example of that slow, methodical rise, and iterative innovation that makes technologies truly lasting. It's not always shockingly abrupt or disruptive. But those innovations are permanently world-changing. Just think, because of the microphone and computer getting together for a blind date in the 40s you can now record your hit album in Garage Band. For free. Or you call your parents any time you want. Now pretty much for free. So thank you for sticking with me through all of this. It's been a blast. You should probably call your parents now. I'm sure they'd love to hear from you. But before you do, thank you for tuning in to yet another episode of the History of Computing Podcast. We're so lucky to have you. Have a great day!

In Story 1, we talk about a weird light in Arkansas. Story 2 is about Georgia Tann, the unparalleled C-word from Memphis. Here’s what we’re drinking this week: Muchacho – 9/10 Deep Eddy Peach – 9.5/10 Did we get anything wrong? Want to tell us about a personal experience or give us some alcohols to try? … Continue reading Piezoelectric Hootenanny →

A subtle tingle to the sole may be just what the doctor ordered to keep seniors on their feet.

For years we have relied on fossil fuels to produce the light, heat and energy we need to live and work. But these supplies are diminishing, and polluting our environment. So can renewable resources step into the breach annd produce enough energy to power the world? In this special Naked Scientists show, live from the Cambridge Science Centre, we talk to some of the researchers trying to do just that, as well as conducting some energy-related experiments of our own... Like this podcast? Please help us by supporting the Naked Scientists

For years we have relied on fossil fuels to produce the light, heat and energy we need to live and work. But these supplies are diminishing, and polluting our environment. So can renewable resources step into the breach annd produce enough energy to power the world? In this special Naked Scientists show, live from the Cambridge Science Centre, we talk to some of the researchers trying to do just that, as well as conducting some energy-related experiments of our own... Like this podcast? Please help us by supporting the Naked Scientists

Researchers at the Georgia Institute of Technology have hit upon a possible answer for powering micro-devices using a cloth that generates power, any time it flexes.

Diese Arbeit präsentiert Ergebnisse an piezoelektrischen Materialien aus der Langasitfamilie, die unter extremen Bedingungen untersucht wurden. Die Einkristalle aus dieser Familie, vor allem La3Nb0.5Ga5.5O14 (LNG) und La3Ta0.5Ga5.5O14 (LTG), sind vielversprechende Materialien für Oberflächenwellen (OFW) –Substratmaterialien, die in der mobilen Kommunikationstechnik der Frequenzsteuerungsgeräte (mobile Kommunikation, Sensoren, usw.) und bei Hochtemperatur- OFW- Anwendung finden. Mit LNG und LTG OFW-Sensorelementen können physikalische Meßgrößen, wie Druck und Temperatur erfaßt werden. Aus diesem Grund sind die Strukturuntersuchungen an LNG und LTG bei verschiedenen Drucken und Temperaturen extrem wichtig. Die Struktur von LNG und LTG ist unter normalen Bedingungen trigonal mit der Raumgruppe P321. In der Struktur sind die schweren Atome polyedrisch von Sauerstoffatomen koordiniert. Vier Polyedertypen bilden decaedrisch-oktaedrische und tetraedrische Schichten. Diese sind in einer A-B- Stapelfolge senkrecht zur c-Achse angeordnet. Die Kristallstrukturen von LNG und LTG wurden mittels Röntgenstrukturanalyse an LNG- und LTG- Einkristallen in Hochdruck- Diamant -Stempel Zellen unter Druck bis 23GPa untersucht. Die Proben für diese Forschungsarbeit wurden von den Forschungsgruppen von B. V. Mill (Rußland) und J. Bohm (Deutschland) freundlicherweise zur Verfügung gestellt. Als druckübertragende Medien wurden Alkohol und Helium benutzt. a- Quarz Kristalle und die Rubinfluoreszenzmethode wurden zur Druckmessung herangezogen. Die Experimente mit Röntgenstrahlung wurden im eigenen Labor und am Hamburger Synchrotronstrahlungslabor (HASYLAB, Beamline D-3) durchgeführt. Die Gitterkonstanten und Reflexintensitäten von LNG und LTG wurden unter Drucken bis 22,8 beziehungsweise 16.7GPa gesammelt. Innerhalb des erforschten Druckbereichs nimmt das c/a- Verhältnis von 0,6232 bis 0,6503 für LNG und von 0,6227 bis 0,6350 für LTG zu. Folglich ist die a-Achse die an stärksten komprimierte Richtung in beiden Substanzen. Damit zeigen LNG und LTG unter Druck ein anisotropes Verhalten, das durch unterschiedliche Bindungsstärken in den Richtungen parallel zu den a- beziehungsweise c- Achsen bedingt ist. Unter hydrostatischem Druck ist die Komprimierung der c- Richtung (also zwischen den Schichten) steif, was wegen der weniger flexiblen Verknüpfung der Polyeder (gemeinsame Kanten) verständlich ist. Demgegenüber ist die Komprimierung innerhalb der ab- Ebene (also innerhalb der Schichten) größer und kann hauptsächlich durch die abnehmenden Volumina und Verzerrungen der Polyeder erreicht werden. Weil die Kristallstrukturen von LNG und LTG wegen der hohen Symmetrie und der Polyederkopplungen sehr steif sind, führt die Komprimierung dieser Strukturen zu einer Zunahme der internen Spannungen und endet bei einem Druck von 12.4(3)GPa für LNG und 11.7(3)GPa für LTG mit einem Phasenübergang in Strukturen mit niedrigerer Symmetrie. In dem untersuchten Druckbereich sind die Kompressibilitäten entlang der c-Achse fast identisch für LNG und LTG. Andererseits sind die Druckabhängigkeiten der a Gitterparameter dieser Materialien nur für die Ausgangsphase ähnlich, während die Achsenkompressibilitäten für die Hochdruckphasen von LNG und von LTG unterschiedlich sind. Die Volumenkompressibilitäten des trigonalen LNG und LTG sind 0.007GPa -1 , die entsprechenden Kompressionsmodule sind 145(3)GPa und 144(2)GPa. Der Kompressionsmechanismus von LNG und LTG kann wie folgt beschrieben werden: Eine Erhöhung des Drucks verursacht eine Reduzierung der Gittervolumina von LNG und LTG. Folglich verringern sich die Abstände zwischen den Ionen. Auf diese Weise werden die größten Kationen (La 3+ ) innerhalb der ab- Fläche verschoben, um die Abstände zwischen den positiv geladenen benachbarten Ionen (Ga 3+ /Nb 5+ (Ta 5+ )) zu maximieren. Auf die gleiche Weise bewegen sich die tetraedrisch koordinierten Ga 3+ -Ionen. Wegen der Anionen-Kationenbindungsverkürzung versuchen die Polyeder zu rotieren. Nun werden diese Drehungen durch die gemeinsamen Ecken und/oder Kanten der benachbarten Polyeder behindert. Außerdem werden diese Bewegungen durch die geringe Flexibilität begrenzt, die durch die Symmetrie (zwei- und drei- zählige Achsen) verursacht wird. So resultiert die Komprimierung hauptsächlich aus Verkleinerungen der Polyedervolumina. Folglich steigen unter zunehmenden Druck die Spannungen innerhalb der Polyeder, vor allem innerhalb der kleinsten Polyeder (GaO4-Tetraeder), wegen deren geringer Flexibilität. Bei einem Druck von 12(1)GPa resultiert die Komprimierung von LNG und LTG in einer Transformation aus der Hochsymmetriephase in eine Niedersymmetriephase. Es kann gefolgert werden, daß dieser Phasenübergang durch die Zunahme der Spannungen innerhalb der Polyeder verursacht wird. Die Hochdruckphase ist verzerrter als die ursprüngliche Phase und beinhaltet mehr Freiheitsgrade für weitere Komprimierungen. Die Hochdruckphasen von LNG und von LTG können in Strukturmodellen mit monokliner Symmetrie (Raumgruppe A2) verfeinert werden. Die Kompressionsmodule sind B0=93(2)GPa und B0=128(12)GPa für die Hochdruckphasen von LNG beziehungsweise von LTG. Die entsprechenden Kompressibilitäten der Hochdruckphasen sind 0.011GPa -1 für LNG und 0.008GPa -1 für LTG. Somit zeigen die Hochdruckphasen unterschiedliche Kompressibilität, die durch eine Nb 5+ - Ta 5+ Substitution gut erklärt werden kann. Die Kompressibilität der Hochdruckphase von LNG ist größer als der entsprechende Wert für das Hochdruckpolymorph von LTG. Dieses Phänomen kann durch die größere Verzerrung von NbO6- Polyedern im Vergleich zu TaO6- Polyedern gut erklärt werden, welche durch die höhere Polarisation der Sauerstoffanordnung bei Nb 5+ -Kationen verursacht wird. Außerdem sind die Kompressibilitäten der Hochdruckphasen größer als die entsprechenden Werte für die Ausgangsphasen von LNG und LTG. Die Beobachtung einer Zunahme der Kompressibilität weis auf zusätzliche Polyederverkippungen hin. In den meisten Fällen ergibt sich die zusätzliche Freiheit aus dem Symmetriebruch. Das erklärt eine (auf den ersten Blick ziemlich unerwartete) erhöhte Kompressibilität der Hochdruckphase. Zusätzlich kann sich durch ein anomales Elastizitätsverhalten eine Steigerung der Kompressibilität der Hochdruckphase ergeben. Bei einer Zunahme des Druckes über 22GPa hinaus wird die Komprimierung der monoklinen Kristallstruktur von LGN vermutlich zu einer drastischen Strukturänderung führen, die von Änderungen der Korrdinationszahlen begleitet ist. Wahrscheinlich werden ähnliche Prozesse auch im LTG statt finden, jedoch unter höherem Druck. Im folgenden Teil dieser Arbeit wird die thermische Expansion der Gitterparameter von LNG, LTG und La3SbZn3GeO14 (LSZG) dargestellt. Die Hochtemperaturmessungen wurden mit dem Pulverdiffraktometer im HASYLAB an der beamline B2 durchgeführt. Die Temperaturabhängigkeit der Gitterparameter von LNG und von LTG wurde an polykristallinem Material bei Temperaturen von Raumtemperatur bis 850°C durchgeführt. Die thermischen Expansionen der Gitterparameter von LNG und LTG sind in diesem Temperaturbereich fast identisch. Die thermischen Expansionskoeffizienten des Gittervolumens aV (24°C- 850°C) von LNG und LTG betragen 22.563(7)x10 -6 °C -1 beziehungsweise 20.651(7)x10 -6 °C -1 . Deutliche Veränderungen der Temperaturabhängigkeit der Gitterparameter werden für die a- Richtung beobachtet. Folglich ist das Verhalten dieser Materialien bei thermischer Expansion ebenso wie bei Komprimierung anisotrop. Für einen Vergleich des Einflusses von Druck und Temperatur auf die Gitterparameter von LNG beziehungsweise LTG wurden die Druck und Temperatur- Abhängigkeiten des c/a- Verhältnisses gemeinsam aufgetragen. Es zeigt sich, dass eine lineare Abhängigkeit besteht. Daraus läßt sich ableiten, dass die Änderung der Gitterparameter von LNG (LTG) während der Abkühlung von 850°C auf Raumtemperatur einer Änderung der Gitterparameter von LNG (LTG) unter Zunahme des Drucks um 1.4GPa entspricht. Die Substanz LSZG, welche in dieser Arbeit untersucht wurde, ist ein weiters Mitglied der Langasitfamilie. LSZG kristallisiert in der monoklinen Symmetrie, Raumgruppe A2. Die Temperaturabhängigkeit der Gitterparameter der monoklinen Phase von LSZG wurden mittels der Röntgenbeugung an polykristallinem LSZG bei Temperaturen von Raumtemperatur bis 800°C untersucht. Bei Temperaturen oberhalb 250(50)°C wurde ein Phasenübergang erster Ordnung festgestellt, welcher sich in Sprüngen der Temperaturabhängigkeiten der Gitterparameter des LSZG äußert. Die monokline Struktur der bei Raumtemperatur und Normaldruck stabilen Phase des LSZG entspricht der der Hochdruckphase von LNG beziehungsweise LTG. Es ist bekannt, daß die Änderungen der Kristallstrukturen bei steigenden Drucken und Temperaturen gegenläufig sind. Aus diesem Grund wird vermutet daß sich die monokline Kristallstruktur des LSZG bei Temperaturen oberhalb von 250(50)°C in eine trigonale Kristallstruktur (Raumgruppe P321) umwandelt, welche der Normaldruckphase von LNG beziehungsweise LTG entspricht. Für eine detailliertere Beschreibung des Phasenübergang von LSZG bei einer Temperaturerhöhung über 250(50)°C hinaus werden weitere Experimente benötigt. Zum Vergleich von strukturellen und physikalischen Eigenschaften seien auch die physikalischen Eigenschaften von LNG und LTG zusammenfassend dargestellt: 1. LNG- und LTG- Kristalle der enantiomorphen Kristallklasse 32 können im Gegensatz zu GaPO4 mittels Züchtung nach der Czochralski- Methode mit ausreichend hoher struktureller Perfektion hergestellt werden. 2. DTA- Messungen von LNG und LTG zeigen keine Änderungen des thermischen Verhaltens bis zu Temperaturen von 1400°C [5]. Da LNG und LTG vermutlich keine Phasenübergänge bis zu ihren jeweiligen Schmelzpunkten bei ungefähr 1470(30)°C haben, sind sie für piezomechanische Anwendungen bei hohen Temperaturen gut geignet. 3. Die Härte von LNG beziehungsweise LTG ist vergleichbar mit der von Quarz. 4. LNG und LTG sind chemisch inert und unlöslich in Säuren beziehungsweise Laugen. 5. Die Breite des Bandpassfilters von LNG oder LTG ist ungefähr dreimal größer als die von Quarz. Folglich sind LNG und LTG für Filter besser geeignet als Quarz. Im Lichte der Ergebnisse aus dieser Forschungsarbeit können folgende Empfehlungen gemacht werden: 1. Bezüglich der hoher Qualität dieser Materialien (die Halbwertsbreite der Reflexionen beträgt 0.0008°) und wegen des großen Streuvermögens, kann empfohlen werden, diese Kristalle als Test- Kristalle für die Justage an Einkristall- Diffraktometer und für Experimente mit harter Röntgenstrahlung zu benutzen. 2. Ebenso wie a-Quarz- Einkristalle [ 58 ], können diese Kristalle als interner Druckstandard in Einkristallhochdruckexperimenten benutzt werden, weil diese Kristalle eine große Anzahl von starken unabhängigen Reflexen besitzen. Andererseits kann die niedrigere Kompressibilität von LNG beziehungsweise LTG, im Vergleich zu a-Quarz, zu einer niedrigeren Druckmessungspräzision führen. Dieser Nachteil wird wiederum durch große Streuvermögen kompensiert. 3. LNG oder LTG können als Materialien für Drucksensoren bis zu sehr hohen Drucken verwendet werden. Wegen des Phasenübergangs von LNG und LTG ist der Einsatz lediglich auf 12(1)GPa begrenzt. 4. Die Temperaturabhängigkeit der Gitterparameter dieser Materialien zeigt keine Anomalie innerhalb des untersuchten Temperaturbereiches (24°C - 850°C). Somit wurde die thermische Stabilität von LNG und LTG bestätigt. Auf diese Weise können LNG und LTG im Austausch für Quarz als Substratmaterialien für Temperatursensoren sehr empfohlen werden.

Fri, 1 Jan 1993 12:00:00 +0100 http://epub.ub.uni-muenchen.de/4218/ http://epub.ub.uni-muenchen.de/4218/1/073.pdf Yan, Yongan; Bein, Thomas Yan, Yongan und Bein, Thomas (1993): Molecular recognition through intercalation chemistry: immobilization of organoclays on piezoelectric devices. In: Chemistry of Materials, Vol. 5, Nr. 7: pp. 905-907.