Initial reported by Erin Kim, 2 November, 2005
I chose the LDTM-028K, a laminated Piezo sensor from measurement specialties. It is different from resistive sensors such as the bend sensor and the photocell sensor because they generate electricity in response to applied stresses. When the piezo film is bent from the mechanical neutral axis, a very high strain within the piezo polymer is created and generates a high voltage. This voltage is created only as the sensor is deformed. The sensor produces positive voltages when they're deformed in one direction, and negative voltages when deformed in the other.
image from www.makingthings.com
- DT Series Elements
The DT series sensor are the simplest and standard form piezo film sensors.The capacitance is proportional to the area and inversely proportional to the thickness of the element.
- LDT Series Elements with Lead Attachment and Lamination
The 'L' in LDT stands for 'laminated' sensor. Typically, a 0.005" (125㎛)polyester layer is laminated to a 28 ㎛ or 52 ㎛ piezo film element. When used in a 'bending' mode, laminated film elements develop much higher voltage output when flexed than non-laminated (i.e., DT series) elements.
TYPICAL APPLICATIONS FOR PIEZO FILM SENSORS
- Car Alarm
- Biomedical Monitoring
- Vibration/Motion Film Sensor
- Dynamic Strain Gages
- Musical Instrument Triggers
- Antitheft Alarm
- Dispensing Verification
- Coin Drop Counters
- Penetration Panels
- Microwave - Sound Pickup
- Washer Imbalance
- Water Flow Sensor
- Shockwave Sensors
- Air-Ranging Proximity
- Robotic Tactile Sensors
- Traffic Sensors
- Vehicle Classification
- Airport Taxiway
Here are more examples using Piezo element.
Make Your Own Acoustic Guitar Pickup__student project
If it ain't got that swing...__student project
Good Application notes from MSI site.
- Maximum Operating Voltage
- Maximum Applied Force
Ampilification -Op amp
Op amp(Operational Amplifier) take a very small voltage signal and amplify it to a range that's readable.
For more technical introduction, see Practical Electronics for Inventors by Paul Scherz & The IC OpAmp Cookbook by Walter C.Jung