The Odour Delivery Module (AGO) is an Ethoscope module that allows us to delivery up to two different olfactory stimuli to fruit flies held in 14mm glass tubes. Odour can be delivered in response to fruitfly behaviour. For instance, following an immobility bout or a crossing of a virtual midline.
<aside> ⚠️ This page describes the creation of a legacy LEGO operated module. We have used this module with success in the laboratory but we are now transitioning to a new system that uses solenoid valves and custom electronics. The new system is easier to build and, if you are building your first AGO, you may want to consider starting with the newer version.
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The AGO can be configured in two different ways: single or dual odour delivery. The frame for dual odour delivery can house two splitters, whereas the frame for single odour delivery houses just one. As the former frame is slightly larger, the 3D printed platforms which support the Ethoscope, are slightly different sizes. Gcode files for two different versions of the 3D printed frame and platform are available upon request. Assembly of the 2 versions of the modules is otherwise similar. The assembled odour delivery module with Ethoscope looks like this (this is an example of a single odour delivery module):
The core of the module is a two ways pneumatic valve that can open or close an airflow. With this module, we use a LEGO pneumatic valve operated by a single servo motor. The motor (blue in the figure below) operates a 3D printed cog that switches the position of the valve opening or closing the connection. Motors are controlled through a USB Lynxmotion servo board connected to the USB port of the ethoscope.
The mainframe can be found here. The battery aligner for motors and valves here. The two pieces that make the cog are found here and here. Motors can be screwed in the support. The valve can be fixed using LEGO technics pins.
We need two USB cables. One will power the machine independently of the PI and the other will transfer serial communication to the lynxmotion.
Cut one of the USB cables keeping the USB-A connector. Strip black cable and separate red and black wires inside. Strip black and red cables by approximately 5mm and use micro screwdriver to secure. In a USB cable, red and black carry +5V and GND respectively.
black cable → into VS1- of the lynxmotion
red cable → into VS1+ of the lynxmotion