Figure 12
(a,b) show the amplitude magnitude changes in the cases when the base step and the microcantilever are self-excited in air, respectively, while the resistance value in the phase shifter is varied. (c,d) show change in the phase difference and the amplitude magnitude, respectively, caused by phase modulation under application of a 400 \(\upmu \)N pressing load while the resistance value in the phase shifter was varied from 10 \(\mathrm{k}\Omega \) to 35 \(\mathrm{k}\Omega \).
