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Low-Voltage Piezoelectric Chips, 0.7 µm - 3.6 µm Travel
75 mm Wires, Black Dot Indicates Positive Electrode
75 mm Wires,
Piezo Chips Tune the Position
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Three-Dimensional Cross Section of Multilayer Piezo with Interdigitated Electrodes (Item # TA0505D024 Shown); Dashed Lines Indicate Cutaway
Thorlabs' piezoelectric actuators are fabricated from layered sheets of piezoelectric ceramic as is shown in the diagram at upper right and described in the Thorlabs' In-House Piezoelectric Manufacturing box below. Electrodes are printed on each sheet before they are layered, and a precision lapping process ensures the height tolerance of each chip is better than ±5 µm. The compact multilayer design results in chips with high resonant frequencies and sub-millisecond response times.
These actuators are characterized by precision movement and produce free stroke (unloaded conditions) displacements from 0.7 µm to 3.6 µm. The maximum displacement of these actuators is achieved when they are preloaded with the maximum displacement load, which is specified for each product. The actual value of the maximum displacement varies for each item and must be experimentally determined; however, the maximum displacement will always be larger than the free stroke displacement. Please see the Operation tab for additional information.
Electrodes are included on each layer of the chip, as this minimizes the voltage required to drive them. Our piezoelectric chips are available with one of four drive voltage ranges: 0 - 45 V, 0 - 75 V, 0 - 100 V, or 0 - 150 V. When your application is highly sensitive to voltage, consider our chips with maximum drive voltages of 45 V or 75 V. For applications that are less sensitive, the 100 V and 150 V options have longer lifetimes. For a complete list of specifications, see the tables below.
The four sides of each of these chips are coated with a ceramic layer that acts as a barrier against moisture. The ceramic layer offers better protection against moisture than an epoxy coating. Screen-printed silver electrodes are printed on the other two sides of the chip, to which the drive voltage is applied. The positive side will be denoted with either a silver "+" or by a black dot. For convenience, many of our products ship with 75 mm wires soldered to these two sides.
To accommodate a variety of loading conditions, flat ceramic or hemispherical ceramic endplates may be purchased as accessories for these chips. In addition, Thorlabs offers conical end cups, which are compatible with ball contacts possessing diameters between 1.5 to 7.0 mm. Please see the Operation tab for information on interfacing piezoelectric actuators with loads, special operational considerations, and data that will allow the lifetimes of these actuators to be estimated when their operational conditions are known.
Piezoelectric chips with custom dimensions, voltage ranges, and coatings are available. Additionally, we support high-volume orders. Please contact Tech Support for more information.
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Dicing the PZT Block into Individual Elements
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Chips After Binder Burnout and Sintering
Thorlabs' In-House Piezoelectric Manufacturing
Our piezoelectric chips are fabricated in our production facility in China, giving us full control over each step of the manufacturing process. This allows us to economically produce high-quality products, including custom and OEM devices. A glimpse into the fabrication of our piezoelectric chips follows. For more information about our manufacturing process and capabilities, please see our Piezoelectric Capabilities page.
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Schematic of TA0505D024W Piezo Chip
Soldering Wire Leads to the Electrodes
Interfacing a Piezoelectric Element with a Load
To accommodate a variety of loading conditions, flat ceramic or hemispherical ceramic end plates may be purchased as accessories for these chips. In addition, Thorlabs offers Conical End Cups which feature concave surfaces that can interface with Ø1.5 mm to Ø7.0 mm hemispherical or curved contacts. To attach a load to the piezo chip, we recommend using an epoxy that cures at a temperature lower than 80 °C (176 °F), such as our 353NDPK or TS10 epoxies or Loctite® Hysol® 9340. Loads should be mounted only to the faces of the piezoelectric chip that translate. Mounting a load to a non-translating face may lead to the mechanical failure of the actuator. Some correct and incorrect approaches to interfacing loads with piezoelectric actuators capped with both kinds of end plates are discussed in the following.
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Actuation of a lever arm using a piezo element fitted with a flat plate (A, Incorrect), and a hemispherical plate (B, Correct).
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Loads properly and improperly mounted to piezo actuators using a variety of interfacing methods.
The image at right shows one incorrect (near-right, A) and three correct approaches for interfacing a flat-bottomed, off-axis load with a piezoelectric actuator. Approaches A and B are similar to the incorrect and correct approaches, respectively, shown in the image at left. Correct approach C shows a conical end cup, such as the PKFCUP, acting as an interface. The flat surface is affixed to the mating surface of the load, and the concave surface fits over the hemispherical dome of the end plate. In the case of correct approach D, a flexure mount acts as an interface between the off-axis flat mounting surface of the load and the flat mounting plate of the actuator. The flexure mount ensures that the load is both uniformly distributed over the surface plate of the actuator and that the loading force is directed along the translational axis of the actuator.
Operating Under High-Frequency Dynamic Conditions
Estimating the Resonant Frequency for a Given Applied Load
Quick changes in the applied voltage result in fast dimensional changes to the piezoelectric chip. The magnitude of the applied voltage determines the nominal extension of the chip. Assuming the driving voltage signal resembles a step function, the minimum time, Tmin, required for the length of the actuator to transition between its initial and final values is approximately 1/3 the period of resonant frequency. If there is no load applied to the piezoelectric actuator, its resonant frequency is ƒo and its minimum response time is:
After reaching this nominal extension, there will follow a damped oscillation in the length of the actuator around this position. Controls can be implemented to mitigate this oscillation, but doing so may slow the response of the actuator.
Applying a load to the actuator will reduce the resonant frequency of the piezoelectric chip. Given the unloaded resonant frequency of the actuator, the mass of the chip, m, and the mass of the load, M, the loaded resonant frequency (ƒo') may be estimated:
Estimating Device Lifetime for DC Drive Voltage Conditions
A ceramic moisture-barrier layer that insulates Thorlabs' piezoelectric devices on four sides is effective in minimizing the effects of humidity on device lifetime. As there is interest in estimating the lifetime of piezoelectric devices, Thorlabs conducted environmental testing on our ceramic-insulated, low-voltage, piezoelectric actuators. The resulting data were used to create a simple model that estimates the mean time to failure (MTTF), in hours, when the operating conditions of humidity, temperature, and applied voltage are known. The estimated MTTF is calculated by multiplying together three factors that correspond, respectively, to the operational temperature, relative humidity, and fractional voltage of the device. The fractional voltage is calculated by dividing the operational voltage by the maximum specified drive voltage for the device. The factors for each parameter can be read from the following plots, or they may be calculated by downloading the plotted data values and interpolating as appropriate.
In the following trio of plots, the solid-line segment of each curve represents the range of conditions over which Thorlabs performed testing. These are the conditions observed to be of most relevance to our customers. The dotted-line extensions to the solid-line segments represent extrapolated data and represent a wider range of conditions that may be encountered while operating the devices.
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For an Excel file containing these fH vs. relative humidity data, please click here.
The data used to generate these temperature, voltage, and humidity factor plots resulted from the analysis of measurements obtained from testing devices under six different operational conditions. Different dedicated sets of ten devices were tested under each condition, with each condition representing a different combination of operational voltage, device temperature, and relative humidity. After devices exhibit leakage current levels above a threshold of 100 nA, they are registered as having failed. The individual contributions of temperature, humidity, and voltage to the lifetime are determined by assuming:
where A1, A2, A3, b1, b2, and c are constants determined through analysis of the measurement data, V is the DC operational voltage, T is the device temperature, and H is the relative humidity. Because the MTTF has a different mathematical relationship with each factor, the dependence of the MTTF on each factor alone may be determined. These are the data plotted above. The regions of the above curves marked by the blue shading are derived from experimental data. The dotted regions of the curves are extrapolated.
Lifetime testing of these devices continues, and additional data will be published here as they become available.
The PKJCUP, PKFCUP, and PKGCUP are 416 stainless steel conical end cups designed to be used with our piezoelectric chips when interfaced with the end hemispheres sold below. The conical cup can accept a ball contact, such as one of the end hemispheres available below, with a diameter from 1.5 to 3.0 mm (PKJCUP), 2.6 to 5.0 mm (PKFCUP), or 3.6 to 7.0 mm (PKGCUP). Using a ball contact with a piezo actuator ensures that the applied stress is restricted to the axial direction, limiting the probability of stress-induced failure. They can be affixed either to a flat face of a piezo chip or to the mechanical device that is being actuated. If affixing a cup to the chip itself, we recommend using an epoxy that cures at a temperature lower than 80 °C (176 °F), such as 353NDPK or TS10 epoxies or Loctite® Hysol® 9340.
The alumina end hemispheres and flat end plates used in our piezoelectric stacks are also available separately in six sizes (see the table to the right). The hemispheres can be used to create a single contact point between a PZT stack and a lever arm. Alternatively, a hemisphere can be used with a compatible conical end cup (sold above). End plates are used to spread the force at the contact point over the entire surface of the piezo stack. When selecting an end hemisphere or flat end plate to adhere to a piezo stack end face, it is important to match the bottom surface area of the hemisphere or plate to the cross section of the piezo stack in order to ensure that forces are spread evenly over the surface. The end hemispheres have a diameter tolerance of ±0.1 mm, and the end plates have a dimensional tolerance of ±0.04 mm. To secure the end hemisphere or the flat end plate to a piezo actuator, any epoxy that cures at a temperature lower than 80 °C is considered safe to use. We suggest using Thorlabs’ 353NDPK High-Temperature Expoy or TS10 Vacuum Epoxy. Additionally, Loctite® Hysol® 9340 can also be used.