In-Phase Bias Modulation Mode of Scanning Ion Conductance Microscopy With Capacitance Compensation

The in-phase bias modulation (IPBM) mode of scanning ion conductance microscopy (SICM), which has advantages of both the dc mode and the traditional ac mode, is immune to low-frequency external electronic interference and potential drift while maintaining a high scanning speed. However, the IPBM mode still suffers from a low-signal-to-noise ratio (SNR). In this paper, we propose a capacitance compensation (CC) method to solve the problem in the IPBM mode of SICM. After CC, the signal level is significantly increased while the noise level remains unchanged. The increased SNR not only improves the image quality but also allows the system to work at a higher modulation frequency, thus increasing potential for fast scan. Experimental results verify the effectiveness of the IPBM mode of SICM with CC.