FTA100 Series: FTA125, 135, 136, 137
The FTA100 Series provides the Quality Assurance market with a low cost, reliable video-based contact angle and surface tension meter. Computer software analyzes drop shapes to give data without operator intervention or judgment. These instruments are simplified versions of the FTA200 Dynamic Contact Angle Analyzer. They are smaller, rugged, and weigh less. Transportable cases are available so they can be shipped or carried easily from site to site by the user.
A pre-aligned, fixed optical system is used along with fixed lighting. These do not need normal user adjustment. Fluid is dispensed from industry standard pipette syringes. These can be preset to dispense specific volumes.
Each of the models has specimen stage hardware intended for specific applications. The same software capabilities are provided in all models. The models include
- FTA125: general purpose, compact
- FTA135: semiconductor wafers
- FTA136: low contact angles on glass
- FTA137: directly measure on very large objects
This is the general purpose model for smaller specimens. It can measure both contact angles and surface tensions. The specimen is placed on a stage and raised to an appropriate level by the rack-and-pinion lift. The specimen can be quite large: up to 250mm in width and 25mm in thickness. Even though the camera is oriented vertically, the optical axis is horizontal because of a 90° turning mirror; the drop is viewed from the side.
For a larger view click on the image below...
Alternate stages are available. The photo below shows a small wafer stage. Micrometer driven stages are also available.
The FTA135 accommodates larger samples than the FTA125, and provides for more precise sample positioning. It is specifically intended for semiconductor wafers but can be used with any large, but thin, specimens. The specimen platter has specific wafer holders that prevent the wafer from directly resting on the platter. Platters for 8 inch and 12 inch wafers are available.
For a larger view click on the image below...
Specially intended for the glass industry, this model views the top of the sessile drop and computes the contact angle from the diameter of the spread drop. This mode requires that the dispensed volume of the drop be known, but the software can automatically measure this if the dispense needle size is known. It is more accurate than the side-view sessile drop method at low angles, say, below 10°. It is less accurate, but still useable, at angles near and above 90°. This unit requires a transparent specimen because the light source is below the object for the top view mode. It can be reconfigured to work as a traditional side view sessile drop analyzer also.
For a larger and different view click on the image below...
This model is similiar to the FTA125 except that its base is removed and replaced by three adjustable feet so the instrument optics is now down close to the specimen surface. The specimen surface can be arbitrarily large since the instrument is entirely above the surface. The viewing angle is still horizontal from the side.
Common Features to All 100 Series
Contact Angle Measurements
The specimen is placed on a stage and raised to an appropriate level by the rack-and-pinion lift. The FTA100 series handles large samples by design. The unique optical design of the instrument looks down on specimens with prisms rather than requiring the specimen to fit between the light source and the camera. A prism turns the viewing angle to the normal side view for sessile drops, except in the case of the FTA136 which is strictly top view. With the specimen in place, the operator dispenses a drop by turning a knob or pushing a button on the pipette dispenser (several types are available as options). The software automatically analyzes the drop shape and computes the contact angle.
Contact angles can be measured over the entire range from 0° to 180°. Optical issues make it difficult to obtain an accurate image at very low contact angles, say 5° and lower. Glare across the top of the image is a problem. The liquid is also very "thin" at the edges, leading to low contrast compared to higher angles. Thus, while there is no analytical limit to measurements at low angles, there are practical issues that limit the utility of automatic analysis. The operator can always perform a manual analysis by pointing at the drop edges at these low angle images. Low contact angles on transparent objects are more easily measured with the top view FTA136.
Both fully automatic and manually-assisted analysis is possible. Manually assisted analysis can always measure over the entire range; it is automatic analysis that has difficulties at the extreme limits. Since automatic analysis of low contact angles is important in some industries, such as the glass industry, the top view FTA136 provides an attractive alternative.
Droplet volumes will typically range from 3 to 15 micro liters. Needles are available in various diameters. An optional calibration standard, consisting of a sapphire ball embedded in a plate, is available so the system accuracy can be checked at any time by the user.
Surface Tension Measurements
Surface tension measurements are provided through pendant drop shape analysis. A calibration standard of high purity water is provided to ensure accuracy of the system.
Surface energy is computed automatically whenever the test fluid is identified to the computer. The popular surface energy models are provided. A database is automatically created of your surface energy calculations.
A log of date-and-time stamped measurements is automatically recorded on disk whenever enabled by the user. This ASCII text log can be printed or copied to floppy diskette. The user can also "freeze" a drop image and save the image to disk in a standard format for printing or use by other programs. This allows confirmation by others of the contact angle and the use of drop images in documentation. The log file can be imported into Excel where averages may be computed for statistical quality control.
The software will run on Windows 98/ME/NT/2000/XP. On-line operator's manual and Help file are included. Software updates and upgrades are furnished without charge to users. Software licenses are sitewide, meaning the software may run on any number of the owner's computers.
The FTA100 series will either capture and analyze single images ("snapshots") or sequences of images ("movies"). The former are suitable for static situations and the latter are used for dynamic samples such as absorption.
A USB camera is available as an option. A few images per second can be captured (versus 60 per second with the standard NTSC video camera). The exact speed depends on computer used. The advantages, to some users, of USB cameras are they will run from a laptop (for portable applications) and a color camera is USB standard.
The instrument uses either an NTSC analog video camera (traditional type) or, optionally a USB camera. The NTSC analog video camera requires a PCI slot in the host computer. The USB camera requires an available USB port. In either case, a few watts, is safely drawn from the host computer. The computer is normally user-furnished, but complete systems including the computer are available from First Ten Angstroms. The USB camera option can be operated from a laptop.
- Instrument chassis
- Adjustable specimen stage (except FTA136 which rests on specimen)
- High resolution camera and lens
- Adjustable volume pipette syringe
- PCI bus frame grabber (unless USB camera chosen)
- Software running on Windows 98SE/ME/NT/2000/XP
- User manual