Back when I used to use incubators (
) , this is what I used :
It's a rubber shelf liner. You can cut several to size & put a fresh one in as often as you want. Clean the dirty ones to re-use.
When choosing bedding, you should always think: if they eat it, is it good for them ? Wood chips are not.
Straw provides no real nutrient value. A good quality alfalfa hay does. But check with your local ag. dept. to see if you have a problem with blister beatles in your area.
And always provide a small type of grit if you have anything in with them that they may eat.
Another thing I always provide for the chicks is a sand bath. They love it & it is good for them !