Fabrication

Step 1 Printing the chamber- The chamber serves as the main feature off which the components are added.

We printed our chamber using PETG plastic at medium quality (0.2mm layer height), 30% infill, upright with no supports. The ceilings in the sidewalls of the chamber are susceptible to noodling, but are also a tough spot for removing supports. Adjusting printer temp and fan speed can help improve print quality.

Step 2 Creating the metal brackets- These rest on the tops of the chamber sidewalls and carry current from the banana clip terminals to the muscle sample.

The gcode to the brackets can be found here. If you'd like to make them using different methods, the dimensions of the brackets are in the hardware file at the top. Please note that there is a unique bracket for each side of the chamber.

Once you have the blanks cut out, put a 90° bend in them 22 mm from the end with the square. We suggest doing this by marking the bracket and placing it in a vice at the line, then hammering it down to a 90° bend.

The holes in the bracket should overlap with the holes in the chamber, but the bracket does not need to be 100% flush around the bend.

Step 3 Trimming the electrodes- The electrodes compose the grid that the muscle lays on.

Simply use wire cutters to cut 8 lengths of wire that are 55 mm long.

ASSEMBLY

Step 4 Lay the electrodes into the chamber. Place each electrode into the wells of the sidewalls, as in the picture.

Step 5 Completing one side- Lay the bracket over the corresponding sidewall. Ensure each screw has a nut installed, then screw the bolts down through the bracket into the chamber, clamping down onto an electrode. Tighten just to ensure that there is a surface connection between the nut and the bracket, and the screw and the electrode.

Step 9 Install suture gates. Stick the ends of the rubber wire into the associated space in the front and rear chamber walls. Use a straightedge to cut the rubber flush at the top of the chamber. Try to ensure the ends at the bottom of the gate are flush to reduce fluid leakage.

Step 10 (Optional): If you are securing the chamber with a ring stand, install the bolt into the hole at the bottom of the chamber. The vice may be needed to secure the chamber as you install it.

Page leader: Malcolm Thuma