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Table 3 Instructions for building the OptoArm (see Fig. 2C)

From: An economical and highly adaptable optogenetics system for individual and population-level manipulation of Caenorhabditis elegans

Steps Goal Instructionsa Critical notes
Step 1 Connecting power In order to connect a DC adapter to the optogenetics system, we use a soldering-free DC plug. The black and red wires of the connecting wire harness (I) should be attached to the DC plug (II, III). Note that the used wire harness has already a 5 kΩ potentiometer pre-installed. When using a different system, make sure to manually add a potentiometer parallel to the switch between the yellow (REF) and gray (CTRL) wires. Determine the center and barrel polarity of the system to ensure appropriate wiring (with a multimeter)
Step 2 Connecting LED and thermal management For appropriate thermal management use a heatsink that fulfills the criteria of the system (see “Thermal management”, Table 1). Clean the heatsink with ethanol before adding a pre-cut thermal adhesive (I). Remove the top-layer of the thermal adhesive and place the LED on top of it (II). Apply firm pressure for at least 30 s with an assembly press that is included with the single rebel led (III). Solder the blue and white wires of the connecting wire harness to the cathode and anode of the LED respectively. Then, cut some pre-cut thermal adhesive in the shape of the lens holder and attach the lens holder via the tape to the heatsink (IV). Finally, by loosening the screw of the lens holder, lenses can be added to or removed from the system (V). It is important to solder when the LED is already on the heatsink to ensure heat dissipation and circumvent overheating of the LED
Step 3 Connecting swtich and LED driver Add the ON/OFF switch (I) and LED driver (II) to the system (III, IV). The driver can be connected to the wire harness by soldering male pin connectors to the wires of the LED driver and clicking them in the connecting wire harness. Note, that the pictures (Fig. 2C) show the serial set-up used in the paper, in which the red-wire coming from the DC plug is connected with the ON/OFF switch before connecting to the LED driver. We recommend to place the switch in parallel to the potentiometer between the yellow and gray wires (See Fig. 2A). The placement of the ON/OFF switch between the CTRL and REF pins, in parallel with the potentiometer provides the best management of inrush power and spikes to the LED.
Step 4 Mounting on the arm: the final OptoArm Add the whole circuitry to a standard flask clamp (I). Use a cross-clamp to fixate the DC plug on the arm (II, III). By placing the OptoArm in either a fine-tuner or a general lab standard, the system can be used for different applications.
  1. a The different steps and roman numerals refer to those used in Fig. 2C