Niklas Snis

Gentle dry etching of P(VDF-TrFE) multilayer micro actuator structures by use of an inductive coupled plasma

To fully utilize the actuator properties of poly(vinylidenefluoride) (P(VDF))-based polymers, the electric field has to be rather high and one way to accomplish this, in particular with low voltage drive signals, is to build multilayered structures. This paper focuses on how to structure poly(vinylidenefluoride-trifluoroethylene) P(VDF-TrFE) by presenting an etch method to create multilayered miniaturized actuators, with intermediate aluminium electrodes. To create inter-connect areas for the multilayer electrodes, a modified Bosch process in an inductive couple plasma (ICP) etcher is used to remove all P(VDF-TrFE) not covered by the electrodes. Since each electrode mask is slightly different from the others, the result is a staircase-like inter-electrode contact area that is connected from above using a conductive adhesive. The developed ICP etch results in high selective etching and a good agreement between theoretical and measured capacitance values. The manufactured cantilevers, consisting of a multilayer on top of a flexible printed circuit (FPC) board, were tested and the resonant stroke was confirmed to agree with expected values. The successful establishment of interlayer connections between the electrodes open up the possibility for batch fabrication of cheap low voltage micro actuators built on a standard substrate used in millions of commercial products.

Evaluation of building technology for mass producible millimetre-sized robots using flexible printed circuit boards

Initial tests of a building technology for a compact three-dimensional mass producible microrobot are presented. The 3.9 × 3.9 × 3.3 mm3 sized prototype robot represents a microsystem with actuators, sensors, energy management and integrated electronics. The weight of a folded robot is 65 mg and the total volume is less than 23 mm3. The design of the interfaces of the different modules in the robot, as well as the building technology, is described. The modules are assembled using conductive adhesive with industrial surface mounting technology on a thin double-sided flexible printed circuit board. The final shape of the microrobots is achieved by folding the flexible printed circuit board twice. Electrical and mechanical studies are performed to evaluate the assembly and it is concluded that the technology can be used for this type of microsystem. Several issues using the presented assembly technique are identified and addressed.

A piezoelectric disc-shaped motor using a quasi-static walking mechanism

A compact piezoelectric motor that comprises good positioning capabilities has been developed. The stator is manufactured with a multilayer structure that lowers the driving voltage to levels that can be provided by the onboard electronics of a future robot application. The motor exploits a walking mechanism by using three bimorphs to move the rotor in a stepwise manner. Height errors between bimorph tips and stator body stemming from the manufacturing process are recognized and their effects on the motion performance is documented and described. With increasing normal force on the rotor several artifacts in the motion pattern are suppressed enabling a motion performance with high resolution. The maximum torque of the motor is 80 µN m at a drive voltage of 50 V and a normal force of 1.15 N.