A portable versatile 3D printed environmental chamber can help answer key questions in the field of organic electronics, particularly related to the degradation of devices under various conditions. The main advantage to using a 3D printed chamber is that it allows for rapid cost affective adjustments to be made, to changing sample or environmental requirements while still maintaining the utility of the basic design. The low cost and the speed of the production using 3D printing allows researches to rapidly modify our designs to suit their purposes.
This includes different device sizes, extra ports, and additional sensors. A feature of the chambers is their method of manufacture. This is an example of one design, a six pixel IV test chamber.
It is made using 3D printed components for the top chamber, a retaining ring, and a bottom chamber. This provides an overview of the chamber's assembly with a device. The o-ring and the gasket are not 3D printed.
For now, focus on the top chamber. Have the interior face of the top chamber facing up. Locate one of the four pilot holes and drill a tapping hole.
When all the holes are tapped, place a brass tapered threaded insert into one of them, smaller diameter down. Press the heated tip of a soldering iron into the threaded insert while applying nominal pressure to move the insert straight down. Stop when the top face of the insert is about one millimeter above the interior face of the top chamber.
While the plastic is still hot use the edge of a straight edge to lightly press the insert to be flush with the chamber face. Allow the plastic to cool for one minute, then add a second insert. Afterward, place the retaining ring over the insert to ensure the holes line up.
Follow the same steps to install inserts in the remaining holes. With the inserts in place, put the o-ring into the circular groove on the chamber face and press it in. Next, get the organic device.
In this case, a six pixel diode. For testing, place the organic device on top of the o-ring. Next, align the retaining rings holes with the metal inserts in the top chamber.
Use screws to fasten the two together, and press the device against the o-ring. Here is an example of a top chamber with a device and retaining ring in place. The o-ring should fit completely inside the groove, free of bersa particulates, and should be compressed between 15 to 25 percent of its cross section for an adequate seal.
Do not crack the sample when tightening the screws. When done, leave the assembled top chamber in a glove box for at least 24 hours. With the top chamber assembly in the glove box, move to work with the bottom chamber.
The bottom chamber has holes for contact pins needed in current voltage measurements. Make each contact pin with a pogo pin and a solder cup. Insert six to seven millimeters of the narrow end of the pogo pin into the solder cup.
Use helping hands to support the parts of the contact pin horizontally. Touch a heated soldering iron tip to the connection region between pogo pin and cup. Press solder into the connection region, and continue heating the area until the solder melts.
When done, a thin smooth layer of solder should cover the area between the two parts all the way around. Solder must be place on the outside of the pin, as soldering the inside will render the pin unusable. Always be sure to check the electrical connection across the pin and cup before and after mounting on the chamber.
Slide the completed contact pin into one of the holes in the exterior face of the bottom chamber. Stop when about 2.2 centimeters of the solder cup extends from the exterior face. Use epoxy suitable for vacuum applications and apply it around the contact pin and hole to prevent air ingress.
Apply the epoxy around the hole, both inside and outside. Ideally, allow the epoxy to cure for 24 hours at 25 degrees Celsius before repeating the steps for each contact pin. For each of the pins, ensure the set resin is white.
It should be solid when pressed. Add leads to the contact pins necessary to connect it to the measurement board. At this point, place the assembled bottom chamber in the glove box with the top chamber and leave it for at least 24 hours.
After 24 hours, return to the glove box for the final assembly. Work within the glove box and apply a KF50 centering gasket to the bottom chamber. Next, align the notches in the two chambers.
Then, place the top chamber onto the bottom one. To secure the parts, open a KF50 clamp and place it around the edge of the two chambers. Tighten the wing nut as much as possible to fasten the bolt.
Leave the completed chamber in the glove box until it is needed. Have a computer and the other necessary equipment for the experiment ready. This includes a source measurement unit and a zero insertion force test board.
Connect a BNC cable from channel one of the SMU to the test board. Connect the SMU to the computer with a USB cable. Also, connect the power supply to the SMU.
Set up the computer software for the measurement. On the SMU, locate the range switch labeled two and toggle it to the on position. Now, bring the fully assembled chamber from the glove box.
Connect the chambers contact pins to the test board. Focus on one pixel and switch the cathode pin to ground. Switch the anode pin to BNC.
Ensure the other pixels are off. Run the software to perform the measurements. In this plot, in light blue is the current density voltage curve of standard organic photovoltaic device inside the chamber under no illumination.
The dark blue curve is for the same device encapsulated with a microscope slide over the active area and sealed with epoxy. These are the same two systems under illumination from a lab light source. The plots show expected diode behavior.
While attempting this procedure it is important to make good electrical connection between the device and the chamber through the use of pogo pins, and between the chamber and measurement board through the use of proper wiring or a support collar. Following this procedure it is possible to make a chamber suitable for short-term testing if care is taken to prevent leaking. Always test the water vapor and oxygen transmission rates into the chamber when using different materials or designs.
This 3D printed environmental chamber provides a cheap versatile and customizable approach to testing device degradation. Researchers can quickly and easily make modifications to suit their own purposes in testing devices.
