Construction of Test Tube Shaker and Spectrophotometer

Creation of test tube shaker:

When generating the experimental design for this project, our mentor, Dr. Wecker, advised that my partner and I use a test tube shaker to ensure that our algae cultures didn't clump. I designed two prototypes. The first prototype was used in our first experiment; our cultures were placed in a box that was spun by a record player. However, this design functioned more as a centrifuge than a shaker, so we still experienced clumping. For our second experiment, I tried to use the record player to shake a box back and forth using a tension string. That design is pictured in the "initial test tube shaker" video above. While this design created the movement we were looking for, the test tube load proved too heavy for the record player motor. In order to remedy this, I created a similar tension-based design using an attic fan motor. This motor was strong enough to initially handle the test tube load, however, it broke down after several hours. While we ran out of time/resources to create another prototype, I think a similar model with a stronger motor could be a promising design.

Creation of the spectrophotometer:

Cora worked to build a spectrophotometer based on a tutorial by Dr. Firth (see works cited). Using an LED diode shining through a cuvette, we were able to use a multimeter to measure optical culture density (as the LED signal strength would be reduced by higher culture density). Our biggest obstacle in using this design was calibrating the instrument as the watch battery we used deprecated in power after a couple uses. Eventually, we used a blank measurement between each culture in order to establish a baseline. This allowed us to callibrate our spectrophotometer to some degree of accuracy, and we were able to get rough culture density data.