The olfactometer is an ethoscope with a different base. The base is built adapting the design from Lin et al. JOVE 2016 (doi:10.3791/54346).
The four-quadrant olfactometer was first developed by Pettersson et al. and Vet et al. to investigate the olfactory behavioral responses of individual parasitic Hymenoptera. Faucher et al. and Semmelhack and Wang adapted the setup to monitor the olfactory responses of individual Drosophila.
Supplemental_Detailed_drawings_of_the_arena.pdf
The paper provides some basic description of proportions and measurements that we adapted in a 3D printable model (onshape). The arena should be printed in CPE (RS 134-8174 for black) or PETG (Amazon.co.uk Red, Real Filament) for it better deals with odours and can be cleaned more easily.
Our 3D printable version of the basic arena. The distance between the vertex is 179mm. The square inscribed inside the arena has a side of 98mm which is smaller than what used in Lin et al (5.4" or 137mm). The acrylic plate we use has a side of 146mm vs 220mm in Lin et al. Proportions are kept the same.
The main arena is locked within two custom cut acrylic plates of 3mm. Each plate is laser cut and measures 146mm x 146mm and held down in place by a 3D printed frame. The size of 146mm allows to cut an acrylic sheet in 6 parts (RS 434-295 for a sheet of 300mm x 500mm x 3mm).
On both sides, the arena has a ridge that accommodates a gasket made out of a nitrile O-Ring cord of 1.6mm (RS 159-1478). The cord is cut to length and squeezed inside the ridge. The structure is locked using M4 nylon fasteners (25mm screws RS 527-713; M4 wingnuts RS 292-596; M4 washers RS 525-745). The four rectangular slots on the side accommodate 3D printed adaptors that allow positioning two LONG laser-cut walls (the same type used for ethoscopes with piNoIR 1 cameras - distance 130mm - onshape). The adapters have an angle of 166 degrees.
The airflow develops from the four corners and for pipe fittings we use M3 threaded to tube barbed connectors (RS 768-1612 - 80p each ) or M3 pneumatic connectors for input (RS 176-1397 for the push in 3mm OD version at 3.9£ or RS 210-086 for the 4mm OD version with speed control).
The pipe fitting inserted on one of the corner, screwed in through the M3 opening. The black rubber is used as a gasket to seal the chamber.
The bottom acrylic plate has a laser-cut central opening of 6.1 mm which should be used for vacuum extraction of odors. The size of the hole is calculated according to this table so that an M7 thread can be carved inside. The hole connects to a 4 mm OD push-in tube (Nylon RS 483-4914 ) through an M7 elbow adaptor (RS 176-1341).
The arena as seen by the raspberry pi camera