Dry Lab

Mosquito trap Documentation

Early July – We designed the trap in SolidWorks (shown here) – a cylinder with only one small hole for mosquitos to come in, which has the bacterial colony on its bottom. After the mosquitos come in, around the hole on the inside, there is circular electric mesh, which electrocutes them as they try to fly around or away. The mesh has two layers, one connected +, the other to -. In the following 5 days, we built our first prototype.

Day 1 of the prototype build: First, we decided to cut a regular shaped cylinder – bottle – in around half and inverted the top part so it is air-tight. Cutting out the cap produced the desired hole. Next, we cut two pieces of mesh out of a bug-zapper machine previously bought from a supermarket. However, due to the material the mesh was made of, we could not have soldered a wire to it and we ran onto the first serious issue.

Day 2: After drawing a model in SolidWorks, we 3D-printed a support for the mesh, a few millimetres wide, which separated the two layers of mesh and glued the two pieces of mesh on the top/bottom of the support using the hot glue. We still had no solution for the issue mentioned. In the meantime, however, we took apart the bug-zapper and cautiously took out the circuit, disconnecting it from its mesh and from the battery, for safety. As we rewired the circuit onto a new battery, we made small adjustments to it, so that it works as it is supposed to for us. We ran into some issues as the connections were not fully functional and decided to continue tomorrow.

Day 3: We resolved the issues with the circuit and made finally managed to attach a wire onto the two pieces of mesh, so the circuitry was complete and functional. Further, we 3D-printed a box for the circuit, which has a screw-removable top. The process took us more or less the whole day, as the versions of the box printed in 3-4 hour-intervals.

Day 4: When the whole circuit was attached, we encountered sparks with no mosquitos hitting the mesh. The mesh electrocutes mosquitos (or anything else for that matter, which we ourselves encountered several times during later working hours) by creating a short-circuit, which causes a fast electric discharge similar to the lightening strike. This meant that something we did not see caused a short-circuit. Since the separation between the two mesh-layers was only a couple of millimetres, our first educated suspect was air. This is a good time to mention that we dealt with voltages of around 10kV, which is usually enough to make a connection between two terminals (+ and -) on that small of a separation and make air an electric conductor.

Day 5: After consulting with a senior engineer, we suspected that the sharp edges could be the places where charge builds up and has nowhere to escape. That is why, using tweezers, we rounded the ends and kept everything else the same. The system worked quite nicely, with an occasional spark. However, given the low quality equipment we generally tried to use in order to simulate a 3rd world environment as much as we could, we accepted that and the first working prototype was built.