Changing sliding characteristics of a droplet on a slope by the shape and orientation of microtriangular projections for droplet transportation

• Mobility of the sliding droplet can be changed by using triangular prism projection. • Difference in the static contact angles was applied to the droplet sliding dynamics. • Apex angle and orientation of the triangular projection change static contact angle. • Hysteresis can be changed by the apex angle and orientation of the projection. • Acceleration characteristics using the triangular projection were clarified. This study provides a method for changing the mobility of a minute droplet by the shape and orientation of a microtriangular prism projection on a slope for droplet transportation. This method applies the characteristics of the static contact angle of a droplet to change the dynamic contact angles of the droplet sliding on a slope. The static contact angle was different at the apex and at the bottom of the isosceles triangular projection, large at the apex and small at the bottom. These characteristics were applied to change the hysteresis of the droplet by placing the apex upward or downward on the slope. This led to closer advancing and receding contact angles and vice versa. The acceleration of the droplet was investigated in terms of the apex angle and orientation of the isosceles triangular projections. The shape of the sliding droplet as a function of the triangular projection was also investigated. The proposed method could change the acceleration of the sliding droplet and directionality to the droplet for an easy movement.