Piezo components can be used as actuator and sensor. Since the design is flexible in shape, length, width, thickness and operating voltage, each solution has its own optimum. Initially for development purpose standard components are used for testing purpose. The range in dimensions is limited to about 70 mm in diameter and 400 mm in length. The maximum stroke for an actuator is 0.5 mm and blocking force can go up to 100 kN. The required voltage can range from 45 to 1000 Volt.
For valves or positioning of smaller loads piezo benders are used. These benders operate in the D31 mode and have stiffness around 5000 [N/m].
Various types of piezo materials are available for optimization for a specific application. The so called hard-doped materials are used in highly dynamic and ultrasonic applications because of their high quality factor and low loss factor. The soft-doped materials are used for quasi static applications where a high stroke is needed. Materials with high sensitivity are used as a sensor.
Design your own actuator !
To design your own piezo actuator is easy to do. In below table the steps are listed and in the last column an example is shown. For clarity the below steps are for a D33 type of piezo actuator only. A D31 actuator or bender is calculated differently. Contact HEINMADE for assistance.
STEPS TO DESIGN YOUR OWN ACTUATOR
| STEPS |
SPECIFICATION |
EXAMPLE |
| 1. What force is required at maximum stroke ? |
Force = F [N] |
400 [N] |
| 2. What stroke is required ? |
Stroke = S [µm] |
25 [µm] |
| 3. What stiffness is required ? |
Stiffness = C [N/µm] |
100 [N/µm] |
| 4. Calculate blocking force ? |
Fbl = F + SxC [N] |
2900 [N] |
| 5. What is the free stroke of the actuator ? |
Sact = S + F/C [µm] |
29 [µm] |
| 6. Surface of the actuator ? |
Aact = Fbl/40 [mm2] |
72.5 [mm2] |
| 7. Length of the actuator ? |
Lact = Sact [µm] / 1.4 [mm] |
21 [mm] |
Sensor
In many application the piezo is used as a sensor to detect a change of force. Through this change of force an electrical field is genererated. The resulting electrical signal can simply be used for on/off switching (touch panels) or power harvesting. The sensor signal itself, however, contains a lot more information which can be used to quantify the force and frequency for all kinds of applications. One commen application is an accelerometer in which the sensitivity (pC/ms-2) of the design is essential.
Active damping
For making small structure feasible, machines have to hold position accurately. To control accurate position at nanometer level all vibrations must be actively damped to subnanometer level. For this application the vibrations are sensed by the piezo sensor and the allocated piezo actuator makes the opposite movement as illustrated, thus damping the vibrations below nanometer level.
Active damping systems upto 6 degree of freedom are developed and our technology makes cross talk levels between actuator and sensor of over 10.000 possible. | 
