DIY Sterlisation Hood
A sterilisation hood is a transparent box that maintains a sterile environment within it. Sterile hoods aim to keep the microbes out of the air, or in other words, to make a Sterile space. This enables specimens to be worked with/prepared in controlled conditions. It uses a heppa filter and a laminar air flow system to achieve this. There is also a UV light that is run for about half an hour before the experiment starts to kill any living bacteria in the hood. there is a small opeaning for the hands to go in and work. equipment in the hood is not taken out to avoid contamination. Trust me this sounds easy but you need alot of patience and material to do this.
You will need,
1) Acrylic sheets-4mm (6 pcs)....2 of dimension 57X61 (cms)-Sides
................................................2 of dimension 57X80 (cms)-Top & Bottom
................................................1 of dimension 62X80 (cms)-Back
................................................1 of dimension 65X80 (cms)-Front
10) M-seal and silica gel(for acrylic sheets)
How our hood works
The hood is made of acrylic sheets. The back of the box has 2 holes at the top right and bottom left corners for the air flow. There is a UV light attached on the top face of the box. It is difficult to find a UV light, so you can use a black light bulb but it is not nearly as effective as the real thing. our air filter uses a simple car heppa filter and an industrial exhaust fan. the fan pulls the air through the heppa filter and blows it back into the box through PVC pipes. We put the fan close to the heppa filter and connected the fan horizontally so the pull is more powerful and effective. the front of the hood was held to the box with L angles so that it can slide up & down. The front is stopped at a height of 16cm. with wooden blocks for the hands to go in. you can also make 2 holes and connect them to gloves to reduce contamination. we also tried to make a robot arm that is put in the hood and does the work in the hood.
Makig the laminar air flow
1. First make the box around the exhaust fan. (We used sun board but you can use something else).the fan needs about 4-5cm distance from the faces of the box.
2. For the fan box take 4 pieces of sun board(fan width+8cm x fan length) and stick them to the sides of the fan in such a way that the fan is in the centre of the pieces. Pull out the wires from or of the pieces.3. Take 2 square pieces(fan length) and cut a hole(pipe diameter) in them. stick them on both open sides of the fan.Seal all sides with M-seal.
4. Take the acrylic sheet with dimension 62x80 cm which is the back side of the box and drill three holes in it. One for the air filter (top right), the second one for the pvc pipe(bottom left) and the third one(bottom right) for the wire of the Uv light to pass. While doing this make sure that the filter, the pipe and the wire exactly fit into the holes and there is no extra space.
5. Stick the heppa filter into the top right hole, on the inside with araldite.
6. Connect the heppa filter to the fan box and then to the inlet at the right bottom corner using the pipes and L shape connectors. Keep the fan close to the filter to increase power.keep the setup as close as possable to the acrylic sheet.
7. Thus the air filter at the top right hole is connected to the inlet via the fan.
8. Seal all the connections and joints with M-seal.
Making the box
9. The two acrylic sheets of dimension 57X61 cm forms the sides of the box. Two sheets of dimensions 57X80 cm form the top and bottom of the box. One of dimension 61x80 cm is used for the back of the box and the one of dimension 65x80 cm for the front of the box.
10. Stick the 2 sides of the hood to the base using super glue in such a way that the 2 sides are on the base and wait for it to dry. You need to use support for it to dry in a right angle.
11. Once it is dry put a layer of silica gel on both sides without moving the support to set it firmly in place.
12. The sides and the air flow system will take about 5 to 7 hours to set.
13. Once everything is set and dry attach the back sheet with the air flow system to the sides and the base with super glue and then silica gel. Try to keep the back against a wall for support.
14. Stick the top in the same way and wait for the gel to completely solidify.15. After ensuring that all the sides are stuck to the base properly , connect the L angles on the sides of the box and two on the base using nuts and bolts for good support for the front cover.
16. Drill holes on the top sheet and connect the UV tube to the box with nuts and bolts.
17. Drill holes and make stoppers with the wooden blocks using nuts and bolts at about 16cms from the base.
18. Finally put the front sheet by making it slide through the L angles.
19. Cover the box with UV filter once it is built. Do not cover the front screen.
20. Your hood is ready.
1. Make sure that the holes drilled on the back side of the box are of perfect size so that there are less chances of contamination.
2. Seal all the gaps in the box with m-seal.
3. While drilling holes in the acrylic sheet make sure that there is proper support so that the sheet doesn’t bend or break.
4. While sealing the pipes connected to the fan, first seal the pipes together with m-seal and then connect the whole thing.
5. The Uv light is switched off while it is being connected.
6. Do not run Uv light for a long time. Stay away when Uv light is running.
7. Make sure the front shutter is held up securely with the stoppers before conducting the experiment.