Fig. (3) Schematic diagrams of the IonWorks single-hole (A) and population patch clamp (PPC) (B) planar array electrophysiology. The IonWorks Quattro System uses a Patch Plate PPC Substrate that contains multiple recording sites per well. Success rates with this substrate are nearly perfect (> 95%), and the recordings and subsequent IC₅₀ determinations are highly reproducible.