More recently, an attractive approach for exploring conformationally changed protein has been reported by Park et al. [49]. In that study, a new type of ISFET charge sensor was developed for the determination of maltose-induced conformational change in maltose binding protein (MBP). As shown in Figure 4, when treated with maltose on the MBP-modified ISFET surface, the structural transition of MBP took place, leading to a substantial drop in the drain current of the ISFET device. The authors demonstrated that the ISFET charge sensor can be effectively utilized to evaluate the intramolecular conformational change in proteins.