“…QCM has also been used to examine the cell attachment process, focusing on the interaction between cultured cells and the surface of attached cells [ [9] , [10] , [11] , [12] , [13] , [14] , [15] , [16] , [17] , [18] , [19] , [20] , [21] , [22] , [23] , [24] , [25] , [26] , [27] , [28] , [29] , [30] , [31] ]. The effects of cell density [ [9] , [10] , [11] , [12] , [13] ] and species [ [14] , [15] , [16] ] on the change in the resonant frequency of a quartz crystal have been studied. Polystyrene (hydrophobic surface), metals (hydrophilic surface), and polypeptides have been used to examine the interaction between the cell surface and cultured cells [ [17] , [18] , [19] , [20] , [21] , [22] , [23] , [24] , [25] , [26] , [27] ].…”