Yes, you can use your microwave to sterilize a sponge. But there are caveats and you need to be careful how you do it.
Firstly, it’s extremely difficult to properly sterilize anything, in the sense that you are trying to kill all bacteria and other harmful pathogens.
In a lab, you would sterilize by using a combination of extremely high heat – far higher than what you can produce in your kitchen – and high pressure.
The thing is, you don’t need perfect sterilization to improve the hygiene of your kitchen, and your microwave can help you do that by sterilizing a sponge.
The way to do this is outlined well by this study . Basically, two minutes of high power will kill 99% of pathogens including things like e coli. This is a good rule of thumb to work with as it’s helpful and easy to do.
To kill nearly all pathogens you must put it in on high for 10 mins. Making this a regular routine with sponges can improve the hygiene of your kitchen and hopefully help the health of your family.