In this paper an electro-mechanical model to describe the behavior of a PVDF multi-layer smart structure is presented and proposed for I-Swarm mm3 microrobot actuators. The study is based on the modal analysis of the partial differential equations governing the motion of an Euler-Bernouilly cantilever beam. A pair of linearly coupled piezoelectric equations between the mechanical and the electrical domains is presented. An important element in the modelization of such materials is the energy losses term. A viscous damping contribution is considered which allows us to extract more realistic constituent equations for the material to work as sensor or actuator. The development of this equation as an infinite linear combination of each mode allows us to extract a compact lumped equivalent electrical circuit to work at any frequency region instead of the classical reduced models.
Nowadays Atomic Force Microscopy is one of the most extended techniques performed in biological measurements. Due to the higher flexibility in respect to conventional equipments, a novel approach in this field is the use of a microrobot equipped with an AFM tool. In this paper it is presented an integrated controller for an AFM tool assembled in a 1 cm3 wireless microrobot. The AFM tool is mounted on the tip of a rotational piezoelectric actuator arm. It consists on a XYZ positioning scanner, based in 4 piezoelectric stacked actuators, and an AFM piezoresistance probe. Two types of AFM working modes are implemented in the controller, i.e., nanoidentation and AFM scanning. Correction of the mismatch of the piezoactuators composing the arm is possible. A programmable PID control is included in the controller in order to get more flexibility in terms of scanning speed and resolution. An IrDA protocol is used to program the parameters of the AFM tool controller and the positioning of the robot in the working area. Then the values of the nanoindentation or of the scanning can be read through the IrDA interface without any other external action.
Due to the strong power and area restrictions, the controller has been implemented in specific logic in a 0.35um technology. The design has been done using functional specifications with high level tools and RTL synthesis. The AFM scanner can be positioned with a resolution of 10 nm and scan areas up to 1 μm2 with an expected vertical resolution of 1nm.