a device containing a thin piece of material that filters (= separates) waste substances from someone's blood when their kidneys (= organs that remove waste and produce urine) are unable to do this in the way that they should

Blood is circulated outside the body through an external filter, called a dialyzer. 血液通过一个被称为透析器的外部过滤器进行体外循环。

A dialyser is also known as an artificial kidney. 透析器又称为人工肾脏。