US Patent 7563329 Monitoring of cleaning process

A method for monitoring a cleaning process for a medical instrument, includes the steps of placing the instrument in a cleaning chamber; placing a soil standard in the cleaning chamber; cleaning the instrument and the soil standard with a cleaning solution; and detecting whether soil remains on said soil standard. The soil standard includes two substantially parallel substrates separated with two substantially equal thickness spacers, wherein a gap is formed between the two substrates with soil in the gap.