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In a close collaboration the team of Micromotion, micro resist technology, BESSY, and LSU-CAMD have successfully mastered the challenges of LIGA production of ultra-precision microparts for Micro Harmonic Drive® gears. The complementary expertise ranging from design and application know-how to process research and technical support resulted in high quality LIGA microparts and superior Micro Harmonic Drive® gears taking advantages of the free 2D design capability and material choice. It is also an excellent example that through contributions from partners with different background and expertise LIGA precision parts can be produced with high quality and yield and for a market competitive price.

PurposeUntil now, the size range of most machines for precision assembly was much larger than the size of the pieces to be handled or the necessary workspace. Flexibly scalable miniaturised production machines can help to develop much more flexible micro production systems. The paper aims to describe the development of a micro‐parallel‐SCARA robot adapted in size to MEMS products.Design/methodology/approachThe robot consists of a miniaturised parallel structure, which provides a high level of accuracy in a workspace of 60 × 45 × 20 mm3. It has a base area of 130 × 170 mm2 and offers four degrees of freedom.FindingsBased on simulations, the degree of miniaturisation in terms of a smaller structure and a high level of accuracy is determined. The results show that a miniaturised hybrid robot with a plane parallel structure driven by miniaturised zero‐backlash gears and electric motors can reach a theoretical repeatability better than 1 μm.Research limitations/implicationsThe first prototype provides good prospects that the concept will be used in a visionary desktop‐factory. As regards the accuracy parameters of the robot, there will be further efforts to optimise the robot's structure and drive mechanism.Practical implicationsThe repeatability of this first prototype is better than 14 μm. A better stiffness of optimised micro‐gears and joints of the structure will guarantee a much better repeatability.Originality/valueThe paper illustrates that the Parvus is one of the smallest industrial robots for micro assembly equipped with a full range of functionalities like conventional industrial robots.

At present the Micro Harmonic Drive is the world’s smallest backlashfree micro gear. Its favourable properties such as high repeatability, high torque capacity, low mass of inertia and high degree of efficiency are proved applied in different applications for semiconductor manufacturing, measuring machines, aerospace and other industries. However for high precise assembly applications often linear adjustments of a few nanometres are required. The common solution for positioning in the nanometres range is the use of piezoelectric effect actuators. The drawbacks are the need for a closed loop control system, overshooting during positioning, local wear, short travel ranges and loss of position without power supply. To overcome these obstacles the advantages of the Micro Harmonic Drive are exploited together with a stepper motor, an eccentric drive and monolithic flexure hinges are combined in a compact unit, called Nanostage. With this setup a travel range of 40 microns and a resolution < 3 nm is achieved. The single sided and double sided repeatability was measured in an open loop control system with < 5 nm and < 10 nm respectively.

The trend to miniaturization cannot be overseen. The use of very small electronic and electro-optical components in a variety of consumer and investment goods is leading to an increasing demand for small-scale servo actuators for micro assembly applications in production equipment. The previous generation of micro gears and micro actuators was not suited to this type of application, because of unacceptable accuracy.

Poly-methylmethacrylate (PMMA), a positive resist, is the most commonly used resist for deep X-ray lithography (DXRL)/LIGA technology. Although PMMA offers superior quality with respect to accuracy and sidewall roughness but it is also extremely insensitive. In this paper, we present our research results on SU-8 as negative resist for deep X-ray lithography. The results show that SU-8 is over two order of magnitude more sensitive to X-ray radiation than PMMA and the accuracy of the SU-8 microstructures fabricated by deep X-ray lithography is superior to UV-lithography and comparable to PMMA structures. The good pattern quality together with the high sensitivity offers rapid prototyping and direct LIGA capability. Moreover, the combinational use of UV and X-ray lithography as well as the use of positive and negative resists made it possible to fabricate complex multi-level 3D microstructures. The new process can be used to fabricate complex multi-level 3D structures for MEMS, MOEMS, Bio-MEMS or other micro-devices.

Electromagnetic actuators play an important role in macroscopic robotic systems. In combination with motion transformers, like reducing gear units, angular gears or spindle-screw drives, electromagnetic motors in large product lines ensure the rotational or linear motion of robot driving units and grippers while electromagnets drive valves or part conveyors. In this paper micro actuators and miniaturized motion transformers are introduced which allow a similar development in microrobotics. An electromagnetic motor and a planetary gear box, both with a diameter of 1.9 mm, are already commercially available from the cooperation partner of IMM, the company Dr. Fritz Faulhaber GmbH in Schonaich, Germany. In addition, a motor with a diameter of 2.4 mm is in development. The motors successfully drive an angular gear and a belt drive. A linear stage with a motion range of 7 mm and an overall size as small as 5 X 3.5 X 24 mm3 has been realized involving the motor, a stationary spur gear with zero backlash and a spindle-screw drive. By the use of these commercially available elements complex microrobots can be built up cost-efficiently and rapidly. Furthermore, a batch process has been developed to produce the coils of micro actuator arrays using lithographic techniques with SU-8 resin. In applying these components, the modular construction of complex microrobotic systems becomes feasible.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.