Analogue Sensors – Research – Piezo element

Analogue sensors

Anagologue signal – time-varying “quantities” – some sort of information. Quatity- time varying = VOLTAGE. Audio signals which can be transferred between computer’s audio card and speakers.

TYPES OF ANOLOGUE SIGNALS – different possibilities of interaction between interaction scenarios.

accelerometer -> detects changes in positions, velocity, orientation, shocks, vibrations. It is sensing motion28526

Light Sensors -> it could be used as a switch on/off, outside lamp – know when is dark enough to light

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Sound sensor -> translate amplitude acoustics to an electric voltage

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Piezo -> detects puls, sound, vibration – it is used in medical purposes and music

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Analogue Temperature sensor – thermosistor -> temperature increase – thermossitor increases, temperature controls system. Lamps are switches automatically.

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Touching sensor – pushing sensorfebb_touch_switch_1(1)

Flex sensor – wearable sensor,

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PIEZO ELEMENT

SEN-10293 ROHS at Sparkfun.ca

+ Low voltages, light and ultrathin,

it could be used for clocks, alarms, calculators, various alarms,

Microcomputers are widely used for microwave ovens, air conditioners, cars, toys, timers, and other alarm equipment. Externally driven piezoelectric sounders are used in digital watches, electronic calculators, telephones and other equipment. They are driven by a signal (ex.: 2048Hz or 4096Hz) from an LSI and provide melodious sound.

■ Applications 1. Various office equipment such as PPCs, printers and keyboards 2. Various home appliances such as microwave ovens 3. Confirmation sound of various audio equipment

PIEZO SENSOR – CONTACT MIC

 

First experimentation was hold by Jacques and Pierre Curie in 1880 when I was experimenting this volage pressure. It is made from ceramics and and single crystal material. This sensor is invented to be reacts on pressure and transform voltage. Usually it is used in medical and environment fields. Greek word piezin means press or squeeze. Contact microphone are usend to detect sound waves in solid materials. Ordinary they wokrs like ears. Contact mics are usually used in solid materials but they could be used in liquds as well if they are waterproof another advantage of piezos they are enable to get vibrations what we cant hear.

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Piezo is used in high-end technology such as medical, mechanical and automotive engineering as well in art. But is also could be used in everyday life, in musical instruments or ultrasonic cleaning jewelry or glass.

OPERATING PROPERTIES FOR A TYPICAL PIEZO FILM ELEMENT

The DT1 element is a standard piezo film configuration consisting of a 12×30 mm active area printed with silver ink electrodes on both surfaces of a 15×40 mm die-cut piezo polymer substrate. 1. Electro-Mechanical Conversion (1 direction) 23 x 10-12m/V, 700 x 10-6N/V (3 direction) -33 x 10-12m/V

  1. Mechano-Electrical Conversion (1 direction) 12 x 10-3V per microstrain, 400 x 10-3V/µm, 14.4V/N (3 direction) 13 x 10-3V/N
  2. Pyro-Electrical Conversion 8V/ o K (@ 25 o C)
  3. Capacitance 1.36 x 10-9F; Dissipation Factor of 0.018 @ 10 KHz; Impedance of 12 KΩ @ 10 KHz 5. Maximum Operating Voltage DC: 280 V (yields 7 µm displacement in 1 direction) AC: 840 V (yields 21 µm displacement in 1 direction) 6. Maximum Applied Force (at break, 1 direction) 6-9 kgF (yields voltage output of 830 to 1275 V)

Operating despriction for piezo element

Lower frequencies (0.5MHz-2.25MHz) provide greater energy and penetration in a material, while high frequency crystals (15.0MHz-25.0MHz)

FIRST GENERATION APPLICATIONS WITH NATURAL CRYSTALS

In fact, during this revival following World War I, most of the classic piezoelectric applications with which we are now familiar (microphones, accelerometers, ultrasonic transducers, bender element actuators, phonograph pick-ups, signal filters, etc.) were conceived and reduced to practice. It is important to remember, however, that the materials available at the time often limited device performance and certainly limited commercial exploitation.

SECOND GENERATION APPLICATIONS WITH PIEZOELECTRIC CERAMICS
1940 – 1965
During World War II, in the U.S., Japan and the Soviet Union, isolated research groups working on improved capacitor materials discovered that certain ceramic materials (prepared by sintering metallic oxide powders) exhibited dielectric constants up to 100 times higher than common cut crystals. Furthermore, the same class of materials (called ferroelectrics) were made to exhibit similar improvements in piezoelectric properties. The discovery of easily manufactured piezoelectric ceramics with astonishing performance characteristics naturally touched off a revival of intense research and development into piezoelectric devices.

The advances in materials science that were made during this phase fall into three categories:

  1. Development of the barium titanate family of piezoceramics and later the lead zirconate titanate family.
  2. The development of an understanding of the correspondence of the perovskite crystal structure to electro-mechanical activity.
  3. The development of a rationale for doping both of these families with metallic impurities in order to achieve desired properties such as dielectric constant, stiffness, piezoelectric coupling coefficients, ease of poling, etc.

All of these advances contributed to establishing an entirely new method of piezoelectric device development – namely, tailoring a material to a specific application. Historically speaking, it had always been the other way around.

This “lock-step” material and device development proceeded the world over, but was dominated by industrial groups in the U.S. who secured an early lead with strong patents. The number of applications worked on was staggering, including the following highlights and curiosities:

  • Powerful sonar – based on new transducer geometries (such as spheres and cylinders) and sizes achieved with ceramic casting.
  • Ceramic phono cartridge – cheap, high signal elements simplified circuit design.
  • Piezo ignition systems – single cylinder engine ignition systems which generated spark voltages by compressing a ceramic “pill”.
  • Sonobouy – sensitive hydrophone listening/radio transmitting bouys for monitoring ocean vessel movement.
  • Small, sensitive microphones – became the rule rather than the exception.
  • Ceramic audio tone transducer – small, low power, low voltage, audio tone transducer consisting of a disc of ceramic laminated to a disc of sheet metal.
  • Relays – snap action relays were constructed and studied, at least one piezo relay was manufactured

It is worth noting that during this revival, especially in the U.S., device development was conducted along with piezo material development within individual companies. As a matter of policy, these companies did not communicate. The reasons for this were threefold: first, the improved materials were developed under wartime research conditions, so the experienced workers were accustomed to working in a “classified” atmosphere; second, post war entrepreneurs saw the promise of high profits secured by both strong patents and secret processes; and third, the fact that by nature piezoceramic materials are extraordinarily difficult to develop, yet easy to replicate once the process is known.

From a business perspective, the market development for piezoelectric devices lagged behind the technical development by a considerable margin. Even though all the materials in common use today were developed by 1970, at that same point in time only a few high volume commercial applications had evolved (phono cartridges and filter elements, for instance). Considering this fact with hindsight, it is obvious that while new material and device developments thrived in an atmosphere of secrecy, new market development did not – and the growth of this industry was severely hampered.

Piezoelectric Ultrasonic Transducers

for the Detection of Gas Bubbles

The measurement of the propagation time is based on alternate transmission and reception of ultrasonic pulses in and against the direction of flow. The sensor performs noncontact detection of air and gas bubbles in the liquid through the tube wall, and thus allows continuous quality monitoring. Two piezoelectric ultrasonic transducers work as transmitter and receiver.

 PEIZO IN AEROSPACE

Piezos are used in micro-thrusters for satellites, where the micro-thrusters are used to position and stabilize the satellite. Naturally, there is a very strong focus on reliability and functionality of products used in space.

How it works
Micro-thrusters can use different technologies, but the technology of interest here is the so-called “cold gas micro-thruster”. In this approach, the thrusters generate a very small and controlled force (<500µN) by expelling a jet of gas, typically Nitrogen, stored in a high-pressure tank. This requires both an accurate control of the pressure of the propellant in the circuit and a fast and precise “dispensing”. Piezo actuators integrated into valves can ensure both functions. For redundancy, the micro-thrusters are fitted with several piezo actuators. The movement of the piezo actuators ensures a fast and precise control of the flow during operation.

Which piezo elements can be used for micro-thrusters for satellites?
On the low-pressure side, the piezo elements integrated in micro-thrusters are selected for their low power requirements, reduced size and mass, high stroke, low force. For this application, a multilayer bending actuator is preferred, providing fast and precise motion in a small package.

Piezo in MUSIC

Peizo is also very popular in modern music as well because it could pick up sound which normal recorder disable to get. Moreover, these microphones could be used in water and they are strong and it is difficult to destroy them. Another advantage is everyone is able to build their own mic. The vibrations are very sensitive and it doesn’t have to used as simple knock sensor.


Justice Yeldham – live @ Supersonic 2012 – full performance from Tinnitus Jukebox on Vimeo.

CONTACT – a multichannel sound installation- from Hannah Mishin on Vimeo.

Scenario 1

Musical Instrument – Piezo would be used as a part of experimental instrument. Or it would midi controller so depending how much I would have them the sound would change.

Scenario 2

Controlling light – special object which would be used as a controller with multiple functions. When you speak it light turn on, thats means the light would be very personal and anyone would be able controls a light. Or it could be physiological light saying how much we talking and how we should talk less and think more.

Scenario 3

Video – Depends on the axis I might be able control an video and sound. Two sensors would independently controls different softwares as output such as puredata and processing or similar. It might be attached to a person who would be able control a piezo by breath. It most interesting scenario for me would be to built hydro mic and get sound from water…

Reference:

http://www.piezo.com/tech4history.html

http://www.piezoinstitute.com/resources/piezo-history/

http://www.noliac.com/applications/item/show/micro-thrusters-for-satellites/

http://thecreatorsproject.vice.com/blog/new-installation-turns-ordinary-surfaces-into-sonic-playgrounds

http://www.medicalceramics.net/Medical_Ceramics.pdf

https://www.nde-ed.org/EducationResources/CommunityCollege/Ultrasonics/EquipmentTrans/piezotransducers.htm

https://experimentalnetwork.wordpress.com/creative-practice-primer-2/creative-practice-primer-techniques-and-technologies-contact-microphones/

http://my.brainshark.com/What-is-a-Piezo-857005951

https://www.sparkfun.com/datasheets/Sensors/Flex/MSI-techman.pdf

http://www.piezoinstitute.com/resources/what-is-piezo/

http://www.cnjude.com/en/product1.htm

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