What you need is 1 cup baking soda and 10 drops of essential oil.
Oregano is one of the powerful oil that can get rid of any icky stuff that you can’t see with your eyes on the bed and Lavender will just give it your mattress a fresh crisp smell. You could do any combination with oils like Palmarosa, Tea Tree, Eucalyptus and Spearmint.
Stir and make sure it is evenly distributed. Put the mixture into the sifter and spread it across your mattress.
Leave it for about 2 to 4 hours. The longer you leave it, the better the results. Then suck the mixture up with a short nozzle vacuum.
Now enjoy the clean and fresh smell of your mattress.