Recent developments in the functionality of micro-electromechanical systems (MEMS), particularly for medical and biological applications, have led to an increasing demand for micromanipulation devices. This paper describes the design, fabrication, and testing of a family of pneumatically driven microgrippers which can be scaled to handle millimetre to nanometre compliant and non-compliant objects, with the potential to control gripping forces. In contrast to conventional actuation methods including piezoelectric, magnetic and thermal, pneumatic actuation has the advantages of large power density, the potential for force control, low cost and simplicity. The reported prototypes were fabricated using straightforward processes, in contrast to previously-reported pneumatically actuated manipulators. The overall aim of the work is to demonstrate a family of low-cost, polymer based micro grippers that can be actuated manually using pneumatic forces (e.g. via a syringe). A version of the device has been successfully fabricated using laser micromachining and assembled to give an output force of up to 8 mN. The pneumatic actuation was implemented in such as way that it can open the jaws of the micro gripper in a precisely controlled way, demonstrated on a prototype for handling various compliant objects smaller than 200 μm in diameter. Finite Element Analysis (FEA) was used to calculate the gripping force, and the results compared with the experimental measurements. The scaling of the demonstrator and its reverse actuation to increase the gripping force are discussed on the basis of the FEA.
- penumatic actuation
- biological manipulation