Research on the Adaptive Sensitivity Scanning Method for Ion Conductance Microscopy with High Efficiency and Reliability.

Scanning ion conductance microscopy (SICM) is a type of in situ measurement technology for noncontact detection of samples in electrolytes with nanoscale resolution and has been used increasingly in biomedical and electrochemical fields in recent years. However, there is an inherent contradiction in the technique that makes SICM's sensitivity and accuracy difficult to balance. Higher sensitivity allows for faster probe speeds and higher scanning reliability but leads to lower accuracy, and vice versa. To resolve this problem, an adaptive sensitivity scanning method is proposed here that is designed to increase SICM's imaging efficiency without reducing its scanning reliability and accuracy. In the proposed scanning method, the sensitivity is automatically switched via the bias voltage based on the probe-sample distance. When the probe is located far away from the sample, the probe then predetects the sample position rapidly with high sensitivity. When the sample has been sensed in the high-sensitivity phase, the probe then detects the sample with low sensitivity. The basic theory and the feasibility of the alterable sensitivity detection strategy is also studied using the finite element method (FEM) and by performing experiments in this work. Finally, through testing of the standard silicon and polydimethylsiloxane (PDMS) samples, the proposed method is shown to increase SICM imaging efficiency significantly by up to 5 times relative to the conventional hopping mode without sacrificing the scanning accuracy and reliability.