Audio and Transducer
Microphone, noise elimination microphone, telephone receiver, dual piezoelectric crystal transducer, headphones, speaker, accelerometer, medical sensorElectroacoustic transducer
Due to the wide frequency range of the PVDF piezoelectric film, ranging from very low frequency to gigahertz working frequency. Utilizing this property, wide-band speakers can be manufactured. These speakers can produce sound without distortion within the very low bass and very high treble ranges, and can also eliminate mechanical noise. They can also be made into microspeakers, microphones, and high-fidelity stereo headphones. In particular, anti-noise transmitting microphones have undergone several improvements and have entered the development and production stage. This transmitting microphone is used in telephones, and in addition to the clear transmission of calls, other noises are filtered out; when used in TV stations, radio stations, and on-site interviews and live recording occasions, it can eliminate noise interference and produce clear sound, achieving a relatively ideal recording and interviewing effect.Water acoustic transducer
An ultrasonic sensor is made using PVDF piezoelectric film and is applied to the annular and linear array probes of 5, 7.5, and 10 MHz B-ultrasound diagnostic instruments, as well as the probes of 20-80 MHz industrial ultrasonic detection instruments. Compared with the commonly used PZT (piezoelectric ceramic) probes, it has a significant improvement in sensitivity and accuracy. The medical ultrasonic sensor made from this film has a simple structure, high sensitivity, and excellent matching with the mechanical impedance of the human body surface. It is used in devices such as finger pulse meters, blood pressure monitors, heart rate monitors, cardiac rhythm monitors, and fetal heart sound detectors.Mechanical-electrical transducer
In the experiments, it was found that when the PVDF piezoelectric film was used as a transducer, the output power per unit volume was about 10 times higher than that of PZT. Under the influence of an electric field, the strain it produced was 10 times greater than that of PZT, which made it very advantageous when used as an electromechanical transducer. Many research institutions and scientific research centers have taken advantage of this property to develop and produce application products, such as: azimuth detectors, electric shutter blinds stress meters, bending sensors, piezoelectric sensors, accelerometers, impact detectors, underground blasting monitoring instruments, mechanical vibration detectors, stress wave monitors for earthquake research, portable testers, etc.Mechanical-electrical transducers and devices
Record player test tone, non-contact switch, telephone dial, typewriter and computer keyboard, blood pressure monitor, optical shutter, fiber optic switch, zoom lens, tactile sensor, display, displacement sensorInfrared and optical devices
Infrared detector, thermal imager, infrared visible light converter, photocopier, reflective detector, laser power meter, fire detector, anti-theft alarmAudio transducers utilize the lateral piezoelectricity of PVDF thin films, and microphones, headphones, and high-frequency speakers have all been commercialized.
Ultrasound and underwater transducers utilize the longitudinal piezoelectricity of PVDF. At room temperature, signals of frequencies up to 500 MHz can be generated. The development of PVDF hydrophones has been very successful. They have good directionality and high sensitivity, bringing a breakthrough in underwater sound reception technology. The new receiving station does not need to emit sound waves but can determine the location of the target from the signals received from the target. Compared with piezoelectric ceramics, the acoustic impedance of PVDF is small, similar to that of the human body and water. When applied to medical ultrasound diagnostic devices, no layers need to be configured, the processing is easy, and there is no need for a sound lens because the ultrasonic wave convergence is good, and clear deep sectional images can be obtained.
Mechanical-electrical transducers are mostly low-frequency devices and thus utilize the transverse piezoelectricity of PVDF. Non-contact switches can be used at the input terminals of telephones, typewriters, calculators, and computers. Tactile sensors are applied in intelligent robots with intuitive judgment capabilities, being closer to human skin than other sensors. In the medical field, PVDF is used in addition to ultrasound diagnostic devices, and can also be made into blood pressure meters, heart sound meters, and blood diagnosis sensors, etc.
The PVDF piezoelectric material also has strong heat sensitivity. The PVDF thermal imager can detect the temperature distribution of the measured object and is widely used in factory safety management and medical fields. By utilizing the thermoelectric property of PVDF, devices such as alarms, anti-theft alarms, non-contact thermometers and laser power meters can also be made.
PVDF piezoelectric films can also be applied in many high-tech fields. In the tactile sensing of robots, PVDF is the most suitable choice because it has both piezoelectric and thermoelectric effects. The reason why we can feel the shape, texture and temperature of objects through touch, as studied, is that human skin can produce piezoelectric and hot spot effects. Currently, tactile sensors made of PVDF piezoelectric films can sense temperature and pressure, distinguish geometric features such as edges, corners and edges, and even recognize Braille. It is believed that in the near future, these sensors will be able to match human skin in certain functions.
Due to the excellent properties of PVDF piezoelectric membranes, such as high mechanical strength, softness without brittleness, resistance to impact, resistance to water and chemical pollution, and ease of processing, the sensors have been more widely applied in household appliances. There are over a dozen types of sensors used in refrigerators and indoor air conditioners, such as sensors for indicating the status of the refrigerator, defrosting and frosting sensors; humidity sensors for maintaining the freshness of vegetables. Long-life and stable humidity sensors for air conditioners; frosting sensors, gas pressure sensors and air flow sensors, etc. Additionally, by utilizing its thermal (piezoelectric) effect, household sensors have transformed from a mere concept in the past to a reality today. For example, there are disaster prevention sensors and intelligent sensors for households. The former can be divided into two categories: one is for detecting gas leaks and precursors of fires; the other is for preventing intrusions by robbers. Intelligent sensors enable the automation and labor-saving of household chores.