The patent [0] does seem a bit more extensive than just wrap it in a membrane. It discusses using venting/gas pressure (from depressing the key) to expel debris

The patent [0] does seem a bit more extensive than just wrap it in a membrane. It discusses using venting/gas pressure (from depressing the key) to expel debris, for instance. [0] http://pdfaiw.uspto.gov/.aiw?PageNum=0&docid=20180068808&IDKey=&HomeUrl=http%3A%2F%2Fpdfaiw.uspto.gov%2F http://pdfaiw.uspto.gov/.aiw?PageNum=0&docid=20180068808&IDK...