Laboratory Equipment Design
January 2021 - July 2021
During my 7-month co-op at a startup in Boston, I worked closely with the research and development team to design and construct equipment to help them conduct experiments at low cost and begin scale-up processes.
One coworker needed an adjustable electrode holder that they could use inside of a glovebox. It had to be highly heat-resistant and electrically insulating, and compatible with many different diameters of electrodes. He asked me for the best that I could make in two days. I machined holes into a scrap piece of boron-nitride ceramic: two through holes on the top, and one threaded hole on each side. When he tightened the bolts threaded into the side holes, they held the electrodes in place. The whole contraption rested on top of the crucible so that it was easy to place and remove.
A longer project that I worked on was testing methods of drying yellow pigments that would preserve the color quality. When the pigments were dried via heat, they turned brown, but air drying took too long. My supervisor experimented with chemical solutions methods to make the pigment more heat resistant, and asked me to try to find a way to get the pigment to dry more quickly without heat. First, I built a bubbler to push dry air through the pigment slurry to speed drying. But there wasn't enough airflow to speed the drying.
Next, I tried spraying the pigment into a tube with a membrane at the bottom to catch the powder but let air through from a tube at the bottom that pumped in dry air. This design was inspired by the way that powdered milk is dried. But the tube was too small for the pigment slurry to have time to dry before it reached the bottom, and the airflow was too strong. The result was a buildup of pressure that made the pigment slurry bubble out of the top of the tube, which you can see in the video on the right.
To fix this problem, I built a larger tube to give the pigment more airtime so it could dry. I also moved the dry air inlet to the top of the tube, attached at an angle so that it would make the pigment swirl around the inside of the tube as it fell. But once again this design was unsuccessful. The pigment was still not dry when it reached the bottom, and with the airflow coming in through the top it just dripped through the membrane into the catch can below.
Then, one of my coworkers suggest that I try making a fluidized bed. This design involved pumping pressurized air through the slurry fast enough and in small enough amounts that it caused the pigment to continue to act like a fluid even as it dried.
This was the most successful design so far, as it actually achieved some drying (and didn't spray pigment slurry everywhere). These photos show the pigment when it was first put into the system and after it was mostly dry a few days later. While the system was far from perfect, it did speed the drying process significantly without ruining the pigment color.
Another project that I worked on was to build a system to agitate a bucket full of slurry. Affectionately called the "Bucket Bouncer" this design was intended to replicate the up-and-down motion of a piece of lab equipment at a larger scale. I built a frame out of 80-20 scraps that we had around, and 3D-printed the other necessary components, including a custom cam and the pulleys for a belt drive mechanism. I also specced and ordered a motor with enough speed and torque for the job.
The system worked as it was designed to, rapidly bouncing the bucket up and down. However, the bucked didn't move as much as I had intended, mostly because I forgot to account for the rim on the bottom of the bucket, so the cam was farther away from the bottom of the bucket than I had meant for it to be. Had I done another cam-based prototype, I would have made the cam larger so that it pushed the bucket up higher, and switched to a hex or d-shaft to account for this increase in the necessary torque. But the chemical engineer that I was building this for decided that an agitator would be more likely to achieve the desired result, so I pivoted away from the cam-driven design.
She wanted me to build something as inexpensive as possible. Since it was going to go inside the slurry, the agitator needed to be acid-resistant. So I decided to use an old kitchen mixer that we had in the lab already and make an acid-resistant blade to go around the existing mixer attachment. It was a challenge to design, as it needed to be watertight and cover most the attachment shaft to protect it from the acid, but also needed to fit around the large end of the attachment. I ended up going with a 2-part design that was sealed with epoxy in the middle. You can see a PLA test print on the right and the acid-resistant PTFE print on the left.
I repurposed the 80-20 frame from the previous design to hold the hand mixer in place on top of the bucket. The attachment fit through a hole in the bucket lid to protect the mixer from the slurry. The system worked like a charm and was used for the rest of my time at the company.
Another project that I worked on was building a device to light the inside of a reaction chamber so that the operator could see more through the viewport. It was a relatively quick project, but did have some interesting constraints--the light source needed to be highly acid and temperature resistant without being overly expensive. I 3D printed a part that held LEDs in place at one end of a glass rod. The rod extended through a large ultratorr fitting on top of the reaction chamber, illuminating the interior while the electronic components remained safely outside.
