Adhesive forces commonly exhibit a monotonic increase or a maximum with increasing relative humidity. However, anomalous behavior has been reported. Here, a numerical model of adhesive forces, comprised mainly of capillary and van der Waals forces, between a tip and a surface is established. It is described by a power law that considers the geometry, the liquid bridge wetting radius, the contact angle, and the separation distance. Capillary forces (sum of surface tension and Laplace pressure) and van der Waals forces are calculated. The latter cannot be neglected in the adhesion even at high humidity. Decrease in adhesion with increasing relative humidity can be attributed to a blunt tip shape, which is validated by experimental data. Specifically, the decrease in adhesion is attributed primarily to a transition from a rounded to a blunt tip shape. Structuring objects at the micro- or nanoscale can either increase or decrease adhesion as a function of relative humidity. This has a wide range of applications in robotic manipulation and can provide a better understanding of adhesion mechanisms in atomic force microscopy in ambient air.

粘附力通常随相对湿度的增加而呈现单调增加或最大值。但是，已经报道了异常行为。在此，建立了在尖端和表面之间的主要由毛细作用力和范德华力组成的粘附力的数值模型。它由幂定律描述，该幂律考虑了几何形状，液桥润湿半径，接触角和分离距离。计算毛细作用力（表面张力和拉普拉斯压力之和）和范德华力。即使在高湿度下，后者的粘合力也不能忽略。随着相对湿度的增加，粘附力的降低可归因于钝头形状，这已通过实验数据进行了验证。具体而言，粘附力的降低主要归因于从圆形到钝头形状的过渡。在微米或纳米尺度上构造物体可以根据相对湿度增加或减少附着力。这在机器人操纵中具有广泛的应用，并且可以更好地理解环境空气中原子力显微镜中的粘附机理。