A design is presented for a relatively large force (0.5 mN) high-precision MEMS clamping mechanism. The clamp is a part of a MEMS transmission electron microscope (TEM) sample manipulator, which needs to be fixed unpowered once positioned. The elastic deformation of the clamp suspension has been optimized in order to not influence the TEM sample manipulator position during clamping. The dimensions of the elastic elements have been further optimized for minimal elastic energy storage, minimizing the force needed for deformation and thus reducing the device area. Fabrication involves a back-etch release process, offering great design freedom, resulting in a compact design.