Team:ETH Zurich/Hardware
Hardware: Make Lab-Life Easier
There are many useful and time-saving tools and pieces of equipment that make everyones life easier while working in a laboratory. Unfortunately, most of them are fairly expensive even though their function is simple.
We designed and produced three items that proved to be useful in the daily lab usage. They can easily be reproduced at low cost and save a lot of time and money. We printed these items with an FLSUN Prusa i3, an affordable and simple 3D-printer that is delivered as a self-assembly kit.
High-Speed Pipette Tip Stacker
As most iGEM teams have to operate on a heavily restricted budget, most of them are forced to refill their pipette tips manually. This is still easy for the larger 1000 µl and 200 µl pipette tips, but becomes especially annoying for the tiny 10 µl tips. Thus, we designed a high-speed pipette tip stacking tool that circumvents touching each tip one after the other. The gadget consists of a rack, a stand, a frame and a comb.
The usage is simple: the rack and the frame are connected by built-in magnets, pipette tips are filled in and the assembled device is heavily shaken until most tips are hanging aligned in the rack. It can then be placed on the stand that enables easy and comfortable further processing. The frame as well as excess tips are then removed and the aligned tips are transferred to the tip box using the comb.
Left:Section of the rack with hole for magnet Middle: Visualization of the frame from the bottom with magnets Right: 3D-printed version of the connected parts of the frame with a hole for a magnet on the smaller wall and a protrusion on the bigger wall
All parts can be 3D-printed. The frame consists of two small and two big walls which we printed with a layer height of 0.4 mm. The same applies for the stand. As the walls have a large surface and are thin, a heated bed is required to avoid early detaching. We had good experience with a temperature of 70° C while we were printing directly on glass.
The rack and the comb were printed with a layer height of 0.2 mm for a smoother surface and less friction between the rack and the tips.
After printing, the walls of the frame were glued together. Additionally, holes are incorporated into the edges of the smaller walls where magnets can be glued into (ø 5 mm). As we printed our device in PLA (poly lactic acid), we did not glue the magnets into the holes but we simply closed them with molten PLA. The same is true for the rack. The magnets stabilise the frame on the rack and makes shaking easier. Furthermore, the larger walls have a protrusion that seal a possible gap between the rack and the wall. It lets the tips slide directly into the grid.
You can download all parts here.
Magnetic PCR-Tube Rack
Left: 3D-printed version of magnetic rack, layer height 0.2 mm Right: Visualization of magnetic rack, created with SolidWorks
Sometimes DNA extraction or purification steps do not work as desired and the nucleic acids are still contaminated with buffer components (e.g. guanidinium chloride) or one needs to purify DNA from a PCR before performing a digestion. Even though agarose gel extraction gives an exact control over the size of the extracted DNA, this is not always required. An easier and faster method of nucleic acid purification is the precipitation with PEG (polyethylene glycol) on magnetic beads1. Compared to conventional column-based DNA purification, this method is also less costly. The required volume for a clean-up of a 50 µl PCR reaction is 40 µl of magnetic beads solution. 5 ml of these cost around 175$ (e.g. Axygen) what makes 1.40$ per clean-up and is less compared to column-based PCR purification kits (e.g. Qiagen, 115$ for 50 reactions) which cost about 2.30$ per clean-up.
For efficient DNA purification with magnetic beads you will need a magnetic rack suitable for PCR tubes. Unfortunately, commercially available magnetic racks exceed the budget of an iGEM team (unless your university is already equipped with them).
Today, 3D-printer are already available for less than 300$ and thus is cheaper than the purchase of magnetic racks. Therefore, it is definitively time to make your own! Our iGEM team designed, produced and tested the herein presented magnetic rack. We used three connected, strong neodymium magnets (40 mm x 10 mm x 5 mm, from supermagnete.ch) that can be removed during the clean-up protocol. This reduces the number of times you have to switch between magnetic- and non-magnetic rack to zero.
The STL file can be downloaded here and is ready for printing. We recommend a layer height of 0.2 mm to achieve optimal results and works well with PLA (poly lactic acid).
96-Well Plate Spacer for Incubation
While we were characterising our biobricks, we faced the problem that we only had one plate reader. To save time, we decided to measure seven plates at once and to measure them every 30 minutes instead of every 10 minutes. In the meantime, the plates were grown in a shaking incubator. The problem was that we needed to fix them in a way that the plates did not move. Normally, for glass bottels and racks the sticky ground works fine. But as the bottom of the plates needed to be clean, we could not just stick them onto the rubber mat. Thus, we designed and printed a spacer for in between the underground and our plate. This way, our plate were protected from direct contact and pollution form the sticky rubber mat but was still tightly fixed in the incubator.
The spacer was printed with the Ultimaker 2 Extended+ with ABS. The inner dimensions of the spacer are 85.4 mm x 127.7 mm. The exact dimensions of the spacer might depend on the printer it is made with. Download the spacer from here
Thanks to the sponsors that supported our project:
