Scanning ion conductance microscopy (SICM), as an emerging non-contact in situ topography measurement tool with nano resolution, has been increasingly used in recent years in biomedicine, electrochemistry and materials science. In the conventional measurement method of SICM, the sample topography is constructed according to the position of the probe at the feedback threshold of the ion current. Nevertheless, for different structures, a constant threshold cannot maintain a constant probe-sample distance. This phenomenon makes the measurement topography inconsistent with the real sample surface. In order to solve this problem and improve the measurement accuracy of SICM, a new ion conductance imaging method based on the approach curve spectrum is proposed in this work. In the new method, the local feature around the measurement point is firstly evaluated according to the change rate of ion current. Secondly, based on the local feature, the corresponding approach curve is searched from the prior approach curve spectrum to accurately evaluate the distance between the probe and the sample. Finally, the sample topography is constructed by the probe position subtracting the probe-sample distance. In this paper, we verify the feasibility of the new imaging method by combining finite element theory and experiments. To examine the measurement accuracy, the standard strip silicon and cylindrical polydimethylsiloxane (PDMS) samples are tested, and the improved imaging method can obtain the topography closer to the real samples and reduce the volumetric measurement error by 5.4%. The implementation of the new imaging method will further promote SICM application in related research fields.

中文翻译：

---

基于逼近曲线谱的高精度离子电导成像方法

扫描离子电导显微镜（SICM）作为一种新兴的具有纳米分辨率的非接触式原位形貌测量工具，近年来在生物医学、电化学和材料科学中得到越来越多的应用。在传统的 SICM 测量方法中，样品形貌是根据探针在离子电流反馈阈值处的位置构建的。然而，对于不同的结构，恒定的阈值不能保持恒定的探针-样品距离。这种现象使得测量形貌与真实样品表面不一致。为了解决这一问题，提高SICM的测量精度，本文提出了一种基于逼近曲线谱的离子电导成像新方法。在新方法中，首先根据离子电流的变化率评估测量点周围的局部特征。其次，基于局部特征，从先验逼近曲线谱中搜索出相应的逼近曲线，以准确评估探针与样品之间的距离。最后，通过探针位置减去探针-样本距离来构建样本形貌。在本文中，我们结合有限元理论和实验验证了新成像方法的可行性。为了检验测量精度，对标准条状硅和圆柱形聚二甲基硅氧烷（PDMS）样品进行了测试，改进后的成像方法可以获得更接近真实样品的形貌，体积测量误差降低5.4%。