In order to design an effective foot surface which can provide adequate friction for a self-propelled medical microrobot moving inside the small intestine, frictional mechanisms between the small intestine inner wall and the foot surface of the robot must be understood. In this paper, mechanical interlocking effect was considered to design the surface of the foot that can generate the desired frictional force. The concept of the design was derived from the hookworm that lives inside the small intestine. Hookwarms are known to adhere to the small intestine wall by interlocking with villi on the surface of the small intestine. The interlocking mechanism was considered as the main frictional mechanism for the design of the microrobot foot surface in this work. 2 mm and 6 mm diameter solid and hollow cylindrical shaped foot specimens were designed and tested to assess the frictional force between the specimens and the porcine small intestine specimen.