Doctors were baffled when the actress' little boy Charlie, now three, fell sick and they struggled to find a cause of his ill health before he was finally diagnosed with Kawasaki disease, which leaves organs and blood vessels inflamed and can lead to heart disease.
There is only a 10 day window to save the heart from serious damage, but no test for a quick diagnosis was available until now.
A leading team of doctors from America's Stanford University have come up with a prototype for a diagnostic test, and Chalke wants fans to help fund a two-year run - the required time period before a new test can become widely available.
On a page set up on Crowdrise.com, she writes, "With this test, no parent will have a sick child with Kawasaki disease and wonder what it is; no child will have silent heart damage that can cost them their life."
The page had already gathered over $30,000 (£19,354) as Wenn went to press. Chalke is seeking $100,000 (£64,500) in donations.