To detect penicillin, they exploited a concept of the ISFET-based enzyme biosensor that employs two pH-sensitive ISFETs, one of which possesses a membrane containing cross-linked albuminpenicillinase, and the other which has a membrane of only cross-linked albumin membrane. Through their study, the authors evidenced that the tested enzyme-based ISFET might be suitable for the rapid detection of small amount of analyte with high sensitivity. Also, since it can provide the feasibility to save the analysis time through the automated penicillin measurement system based on ISFET, this ISFET-based enzyme biosensor has been suggested for the analysis of complex samples.