The FTA4000 is a video drop shape analysis system optimized for extremely small drops. Both sessile drop contact angle and pendant drop surface tensions can be measured. Surface regions as small as 50 microns in diameter can be probed with drop volumes as low as 10 picoliters. The image below shows the pump and circular sample stage directly below the yellow hub dispense needle.
Controlled delivery of the test fluid becomes difficult at smaller droplet volumes because of the increased interfacial pressure expressed by the Young-Laplace equation. The unique NanoDispense electronic pump provides control for contact angle measurements for sessile drop volumes in from below 10 picoliters to many nanoliters. The tip has a motorized Z axis. It is positioned in X and Y by micrometers. The pump accepts a variety of Luer-hub needles from small stainless steel needles to glass capillaries.
A round stage, approximately 100mm in diameter, rotates samples under the dispense tip. Samples are mounted around the periphery of the stage. The stage is rotated and positioned in Z by stepper motors. The stage can be easily removed to allow the user to fit their own or to mount fixtures on the stage. Approximately 35mm of Z travel is provided by the motor.
Two microscopes are fitted as standard equipemnt: an analytical microscope to capture the drop shape image and look-down alignment microscope to view the specimen and the droplet from a 60 degree angle.
The analytical microscope has a zoomed horizontal field of view from 2mm down to 200 microns. The viewing angle is adjustable to 0° or 3° with respect to the specimen surface, so it is looking horizontally at the drop. This image is back-lit by a high intensity LED source
The look-down alignment microscope has a zoomed horizontal field of view from 6mm down to 1mm. An incandescent top light is provided. This is a diffuse light and gives better images in look down mode than a focused light would. The look-down microscope has a seperate video channel and appears in a seperate window within the program than the main analytical image.
Both microscopes feature internal focus for easy setup. You can capture and save images from both cameras. The image below shows the look down image of a glass capillary tip approaching a semiconductor sensor sample.
For a selection of sample NanoDispense images and data, see FTA4000 NanoDispense Examples.
The image below shows the deposition of an 10 picoliter drop on a surface for contact angle measurement. The tip moves very quickly and so generates a blur in this image. You can see the vestige of the tip coming down from above and its reflection image coming up from below.
The entire instrument is enclosed to protect the measurement from air currents and rapid temperature changes. The design is clean room compatible. All components are mounted on a single vertical surface plate for rigidity and ease of access.
For a larger view click on the image below...
The standard FTA4000 hardware includes:
High resolution analytical camera and zoom microscope
High intensity LED backlight
PCI frame grabber card (computer optional)
NanoDispense piezo-electric controlled drop dispense
Stepper motor driven pump and tip Z axis
Stepper motor driven rotation and Z sample stage
Look-down alignment camera and zoom microscope
Look-down diffuse illumination source
Image capture is dynamic with variable resolution from 1/60 second to hours per image. Individual images or sequences up to hundreds of images long may be captured. All analysis is performed on images already captured in memory. Images may be captured from both microscopes.
The software will run on Windows 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.
Static or equilibrium contact angle
Advancing contact angle
Receding contact angle
Sessile drop spreading
Surface energy from contact angles
Work of adhesion/adhesion tension
Zisman critical wetting tension
The following options are available. The high speed camera options are useful for ink jet studies. The X-Y motorization on the sample stage is useful for studying semiconductor chips where you want to place the droplet on a specific feature. If you have needs not covered here, please contact FTA.
360 Frames Per Second camera
Split beam optics to accomodate external high speed camera such as Redlake's
High intensity halogen source (approximately 150W) for high speed imaging
X-Y Sample stage motorization (Z standard)