The MEMS Handbook MEMS Applications (2nd Ed) - M. Gad el Hak Episode 1 Part 10 ppsx

has been presented [Ebefors, 2000]. Most of these techniques could be arranged in array configurations for distributed micromotion systems (DMMS). For out-of-plane actuators using an external force field it is difficult to control each individual actuator in a large array of folded structures. Therefore, a synchronous jumping mode is used to convey the objects or move the device itself. This jumping mode involves quick actuation of all the actuators simultaneously, which forces the object to jump. When the object lands on the actuators (located in their off position), the object has moved a small distance and the actuators can be actuated again to move (walk or convey) further [Liu et al., 1995]. A critical aspect of large distributed micromotion systems based on arrayed actuators and distributed (or collective) actuation is the problem associated with the need for the very high yield of the actuators [Ruffieux and Rooij, 1999]. Just one nonworking actuator could destroy the entire locomotion principle. Therefore, special attention must be paid to achieve high redundancy by parallel designs wherever possi- ble. These aspects will be further addressed in Section 7.5.3. 7.5 Microrobotic Devices As pointed out in Section 7.2, a microrobotic device can be either a simple catheter with a steerable joint (Figure 7.2a), or a complex autonomous walking robot equipped with various microtools as in Figure 7.2o. Between these two extremes are microgrippers and microtools of various kinds, as well as micro- conveyers and walking microrobot platforms. Each of these three microrobotic devices will be presented more in detail in the following discussion. Section 7.6 describes more complex microrobotic systems where both microtools and actuators for locomotion are integrated to form so-called microfactories or desk-to-manipulation stations. Also, multirobot systems and communication between microrobots in such multirobot systems will be discussed. 7-14 MEMS: Applications Actuator (a) Object Air flow Air flow Air flow off off off Pressure Pressure Front view of a nozzle on (b) A closed nozzle (c) FIGURE 7.7 Electrostatic-controlled pneumatic actuators for a one-dimensional contact-free conveyance system. (a) Concept for the arrayed pneumatic conveyer (i.e., contact-free operation). (b) and (c) Mechanism for flow control by electrostatic actuation of nozzle when (b) the electrostatic nozzle is in the normal situation (off) and (c) when voltage is applied to one electrode (on). (Illustration printed with permission and courtesy of H. Fujita, University of Tokyo.) © 2006 by Taylor & Francis Group, LLC 7.5.1 Microgrippers and Other Microtools The first presented microrobotic device was based on in-plane electrostatic actuation [Kim et al., 1992]. This microgripper had two relatively thin gripping arms (thin-film deposited polysilicon) as shown in Figure 7.8. Other microgrippers based on quasi-three-dimensional structures with high-aspect-ratios fabrication techniques (beams perpendicular rather than parallel to the surface) have also been presented [Keller and Howe, 1995; 1997] (Figure 7.9). These kinds of grippers, so-called over-hanging tools, are formed by etching away the substrate under the gripper. One critical parameter for the in-plane technique is how to achieve actuators with large displacement and force generation capabilities. Thermal actuators are known for their ability to generate high forces. A thermal actuator made from a single material would be easy to fabricate, but the displacement due to thermal expansion of a simple beam, for example, is quite small. This is a general drawback for in-plane actuators that occurs independently of the fabrication technique used. However, by using mechanical lever- age, large displacements can be obtained, as was demonstrated by Keller and Howe (1995). They used a replication and micromolding technique, named HEXSIL, to fabricate thermally actuated microtweezers made from nickel and later in polysilicon [Keller and Howe, 1997]. In the HEXSIL process [Keller, 1998a] Microrobotics 7-15 Si wafer Si die Si die Conducting polysilicon lines Support cantilever p + -support cantilever D rive arm Extension a rm Closure d river Diamond saw cuts Insert Microgripper Double-stick tape ZIF socket (legs removed) Alignment window V-groove PSG Poly 7 mm 1.5 mm 400 µm 500 µm Support cantilever Si wafer (c) (a) (b) Support cantilever Si die FIGURE 7.8 (a) Schematics of the microgripper unit (top and cross-sectional view). (b) Schematic showing grip- per packaging and electrical access and a photograph of the packaged gripper. (c) SEM photograph showing a close- up of the gripper jaws and the comb-drive structures and extension arms. (Illustration printed with permission and courtesy of C J. Kim, UCLA.) © 2006 by Taylor & Francis Group, LLC the mold is formed by deep trench etching in the silicon substrate. A sacrificial layer of oxide is deposited in the silicon mold which is then filled with deposited polysilicon. Then the polysilicon structure is released from the mold by sacrificial etching of the oxide. Afterwards, the mold can be reused by a new oxide and polysilicon deposition process. One advantage of this process is the ability to make thick (100µm or greater) polysilicon structures (quasi-three-dimensional structures) on which electronics can be integrated. Figure 7.9b shows a close-up of the leverage design for the HEXSIL microtweezer; a large beam is resistively heated by the application of current, and subsequently expansion causes other beams in the link system to rotate and open the tweezer tips. When cooled, the contraction of the thermal element closes the tweezers. Leverage and linkage systems (sometimes combined with gears for force transfer) are useful techniques for obtaining large displacements or forces that can be used for thermal actuation as well as electrostatic comb-drive actuators [Rodgers et al., 1999]. Several publications on design optimization schemes for var- ious leverage techniques applied to thermal actuators (so-called compliant microstructures) have been presented [Jonsmann et al., 1999]. Another way to achieve a leverage effect is to use clever geometrical designs for single material expansion. One such method is the polyimide-filled V-groove (PVG) joint technology shown in Figure 7.10. The PVG joint technique has also been used for microconveyers and walking microrobots, as will be described in Sections 7.5.2 and 7.5.3. The purpose of the PVG joint microgripper in Figure 7.10 is easy integration with a walking microrobot platform. Several publications on LIGA-based microgrippers have been presented. The reason for using LIGA is to get quasi-three-dimesnsional structures (thick structures) similar to the HEXIL tweezers in Figure 7.9. The LIGA process has also been used to produce single material (unimorph) in-plane thermal actuators for micropositioning applications. Guckel et al. (1992) presented an asymmetric LIGA structure with one “cold” and one“hot” side to generate large displacements (tenths of a millimeter) with relatively low power consumption, as illustrated in Figure 7.20a. More recently, this approach was used by Comotis and Bright (1996) for surface micromachined polysilicon thermal actuators. With this in-plane actuator they have successfully fabricated over-hanging microgrippers. As an alternative to single-material expansion actuators, bimorph structures could also be used for out-of-plane acting gripping arms [Greitmann and Buser, 1996]. A bimorph microgripper for automated handling of microparts is shown in Figure 7.11. This device consists of two gripping arm chips assembled together. Each gripper arm has integrated heating resistors for actuation of the bimorph and tactile piezoresistors for force sensing. Several different approaches to obtain three-dimensional microgrippers working out-of-plane like the ones in Figures 7.10 and 7.11 exist. One commonly used approach is use of the surface-micromachined polysilicon microhinge technology shown in Figures 7.3a–e. Such microhinges have been used both for microgrippers and for articulated microrobot components [Pister et al., 1992; Yeh et al., 1996]. 7-16 MEMS: Applications ( a ) ( b ) FIGURE 7.9 Photograph of fabricated HEXSIL tweezers. (a) Overview of the overhanging microtweezers with a compliant linkage system. (b) Close-up of the 80-µm-tall HEXSIL tweezers. The tip displacement between the closed and open position is typically 40 µm with a time constant Ͻ0.5 s for a typical actuation power of 0.5 A at 6 V. (Reprinted with permission from MEMS Precision Instruments, Berkeley, CA and courtesy of C. Keller.) © 2006 by Taylor & Francis Group, LLC One major drawback of these microgrippers (mainly based on thermal or electrostatic actuation) is found in biological applications. Microgrippers based on thermal, magnetic, or high-voltage electric actu- ation could easily kill or destroy biological and living samples.The pneumatic microgripper presented by Kim et al. [Ok et al., 1999] avoids such problems. An alternative to heating grippers (such as the ones shown in Figures 7.10 and 7.11, which require relatively high heating temperatures) is the use of shape memory alloy (SMA) actuators. Microgrippers based on SMA often require lower temperatures than thermally actuated bimorph or unimorph grippers. SMA-based three-dimensional microgrippers have been used to grip (clip) an insect nerve for recording the nerve activity of various insects [Takeuchi and Shimoyama,1999]. Microrobotics 7-17 FIGURE 7.11 Photograph of a microgripper based on bimorph thermal actuation and piezoresistive tactile sensing. (Reprinted with permission from Greitmann, G., and Buser, R. [1996] Sensors and Actuators A 53[1–4], pp. 410–415.) Cured polyimide Heaters for thermal actuation ∆x Polyimide joint actuator Piezoresistors for force sensing Silicon arm for gripping Silicon arms on-position (heated) Silicon arms off-position (cold) 4 piezoresistors in a full Wheatstone bridge configuration for force sensing FIGURE 7.10 Concept of a microgripper fabricated by polyimide V-groove joints. (Ebefors, T. et al. [2000] “A Robust Micro Conveyer Realized by Arrayed Polyimide Joint Actuators,” IOP Journal of Micromechanical Microengineering 10[3], pp. 77–349.) The polyimide in the V-grooves expands due to heating and the gripping arms are opened. Self-assembling out-of-plane rotation of the arms as well as the leverage effect for single material expan- sion are accomplished by the well-controlled geometrical shape of the V-groove. Polysilicon resistors are used both as resistive heaters and as strain gauges for force sensing. © 2006 by Taylor & Francis Group, LLC In the biotechnology field — for example, the growing area of genomics and proteomics — microtools for manipulation of single cells are of major importance. In particular, massive parallel single-cell manipulation and characterization by the use of microrobotic tools are very attractive. In this type of application, the microgrippers usually must operate in aqueous media. Most of the microgrippers presented so far in this 7-18 MEMS: Applications A a Top view B a C a D a E a a a a a a SiO 2 Ti Au BCB PPy Cross section at a-a FIGURE 7.12 Schematic drawing of the process steps for fabricating microrobotic arms (in this case, an arm with three fingers arranged in a 120° configuration) based on hinges (micromuscle joints) consisting of PPy(DBS)/Au bimorph structures. (A) Deposition and patterning of a sacrificial Ti layer. (B) Deposition of a structural Au layer and etching of the isolating slits. (C) Patterning of BCB rigid elements. (D) Electrodeposition of PPy (conductive poly- mer). (E) Etching of the final robot and electrode structure and removal of the sacrificial layer. Each microactuator is 100 µm ϫ 50 µm. The total length of the robot is 670 µm, and the width at the base is either 170 or 240 µm (depend- ing on the wire width). (Reprinted with permission and courtesy of E. Jager, LiTH-IFM, Sweden.) © 2006 by Taylor & Francis Group, LLC review cannot operate in water because of electrical short-circuiting, etc. One possible solution is to use conductive polymers.Such conductive polymers,which undergo volume changes during oxidation and reduc- tion, are often referred to as electroactive polymers (EAPs) or micromuscles. These kinds of micromuscles have been used as joint material for microrobotic arms for single-cell manipulation devices [Smela et al., 1995; Jager, 2000a,b]. Figure 7.12 describes the fabrication of a microrobot arm based on a polypyrole (PPy) conductive polymer. During electrochemical doping of PPy, volume changes take place which can be used to achieve movement of micrometer-size actuators. The actuator joints consist of a PPy and gold bimorph structure, and the rigid parts between the joints consist of benzocyclobutene (BCB).The conjugated polymer is grown electrochemically on the gold electrode,and the electrochemical doping reactions take place in a water solution of a suitable salt. The voltages required to drive the motion are in the range of a few volts. One of the many experiments conducted with the various robot arms fabricated with the PPy micro- muscles is shown in Figure 7.13. The drawback of microrobotic devices based on the conductive polymer hinge (or “micromuscles”) is that they cannot operate in dry media. 7.5.2 Microconveyers Recently, a variety of MEMS concepts for realization of locomotive microrobotic systems in the form of microconveyers have been presented [Riethmüller and Benecke, 1989; Kim et al., 1990; Pister et al., 1990; Ataka et al., 1993a,b; Konishi and Fujita, 1993; 1994; Goosen and Wolffenbuttel, 1995; Liu et al., 1995; Böhringer et al., 1996; 1997; Nakazawa et al., 1997; 1999; Suh et al., 1997; 1999; Hirata et al., 1998; Kladitis et al., 1999; Ruffieux and Rooij, 1999; 2000; Smela et al., 1999; Ebefors et al., 2000]. The characteristics for some of these devices are summarized in Table 7.3, where the microconveyers are classified in two groups: contact-free or contact systems, depending on whether the conveyer is in contact with the moving object or not, and synchronous or asynchronous, depending on how the actuators are driven. Examples of both contact and contact-free microconveyance systems were shown in Figures 7.6 and 7.7,respectively. Microrobotics 7-19 (A) (B) (C) (D) FIGURE 7.13 (A)–(D) Sequence of pictures (left) showing the grabbing and lifting of a 100-µm glass bead and schematic drawings (right) of the motion. In this case, the arm has three fingers, placed 120° from each other (Figure 7.12). The pictures do not illustrate the fact that the bead is actually lifted from the surface before it is placed at the base of the robot arm. This is illustrated in the second sketch on the right where the lifting stage is shown in gray. (Reprinted with permission and courtesy of E. Jager, LiTH-IFM, Sweden.) © 2006 by Taylor & Francis Group, LLC 7-20 MEMS: Applications TABLE 7.3 Overview of Some Microconveyance Systems Moved Length per Maximum Object/Load Stroke/ No. of Principle a Velocity Capacity Frequency Actuators/Size Ref. CF: pneumatic air bearing Slow Flat Si pieces/ 100–500 µm/ Not specified [Pister (for low-friction levitation) ϩ Ͻ1.8 mg max at 1–2 Hz et al., 1990] electrostatic force for driving CF: magnetic levitation 7.1 mm/s b Nd–Fe–B Not specified Not specified [Kim et al., (Meissner effect) ϩ magnetic magnet slider/ 1990] Lorentz force for driving 8–17 mg C: array of thermobimorph 0.027– Flat Si piece/ ∆x ϭ 80 µm 8 ϫ 2 ϫ 16 legs/ [Ataka polyimide legs c (cantilevers); 0.5 mm/s 2.4 mg (f Ͻ f c ; 33 mW)/ 500 µm/total et al., 1993] electrical heating (asyn) f c ϭ 10 Hz area: 5 ϫ 5 mm 2 CF: array of pneumatic valves; Not Flat Si piece/ Not specified/ 9 ϫ 7 valves/ [Konishi electrostatically actuated specified 0.7 mg f ϭ 1 Hz 100 ϫ 200 µm 2 / and Fujita, (pressure) total area: 2 ϫ 3 mm 2 1994] C: array of magnetic inplane 2.6 mm/s d Flat Si pieces/ ∆x ϭ 500 µm/ 4 ϫ 7 ϫ 8 flaps/ [Liu et al., flap actuators; external Ͻ222 mg f c ϭ 40 Hz 1400 µm/total 1995] magnet for actuation (syn) area: 10 ϫ 10 mm 2 C: array of torsional 5 µm Slow Flat glass piece/ ∆x ϭ 5 mm/f c 15,000 tips 180 ϫ [Böhringer high; Si-tips; electrostatic Ϸ1 mg high kHz-range 240mm 2 /total area: et al., 1996; actuation (asyn) 1000 mm 2 1997] C: array of thermobimorph 0.2 mm/s Silicon chips/ ∆x ϭ 20 µm/f c 8 ϫ 8 ϫ 4 legs/ [Böhringer polyimide legs; c thermal 250 µN/mm 2 not specified 430 µm/total area: et al., 1997; electrostatic actuation (asyn) 10 ϫ 10 mm 2 Suh et al., 1997] CF: Pneumatic (air jets) 35mm/s e Sliders of Not specified 2 ϫ 10 slits/ [Hirata (for flat Si/ Ͻ60 mg 50 µm/total area: et al., 1998] objects) 20 ϫ 30 mm 2 C: array of erected f Si-legs; 0.00755 mm/s Piece of plastic ∆x ϭ 3.75 µm 96 legs/270 µm/ [Kladitis thermal actuation (asyn) film/3.06 mg (f Ͻ f c ; 175 mW)/ total area: et al., 1999] f c ϭ 3 Hz 10 ϫ 10 mm 2 CF: array of planar 28 mm/s g Flat magnet ϩ Not specified Ϸ40 ϫ 40 coils/ [Nakazawa electromagnets (unloaded) external load/ 1 ϫ 1 mm 2 /total et al., 1997; Ͻ1200 mg g area: 40 ϫ 40 mm 2 1999] C: array of non-erected Not specified Not specified ∆x ϭ 10 µm/ 125 triangular [Ruffieux Si-legs; piezoelectric or (f ϭ 1 Hz‚ 20 mW) cells (legs) 400 µm and Rooij, thermal actuation (asyn) f c Ϸ 30 Hz (300 µm) long on 1999] (thermal)/f c high a hexagonal chip kHz-range approx. 18mm 2 (piezoelectric) C: array of erected c Si-legs; 12 mm/s h Flat Si pieces ϩ ∆x ϭ 170 µm h 2 ϫ 6 legs/500 µm/ [Ebefors thermal actuation of external load/ (f Ͻ f c ; 175 mW)/ total area: et al., 2000] polyimide joints (asyn) 3500 mg f c ϭ 3 Hz i 15 ϫ 5 mm 2 a C ϭ contact; CF ϭ contact-free; asyn ϭ asynchronous; syn ϭ synchronous. b The superconductor requires low temperature (77K). c Self-assembled erection of the legs. d Estimated cycletime Ϸ25 ms (faster excitation results in uncontrolled jumping motion) and 0.5 mm movements on 8 cycles [Liu, 1995]. e For flat sliders. The velocity depends on the surface of the moving slider (critical tolerances of the slider dimensions). f Manual assembly of the erected leg. g Depends on the magnet and surface treatment. h Possible to improve with longer legs and more V-grooves in the joInternational. i Possible to improve. Thinner legs with smaller polyimide mass to heat would increase the cut-off frequency, f c ϭϾ larger displacements at higher frequencies. © 2006 by Taylor & Francis Group, LLC Microrobotics 7-21 Contact-free systems have been realized using pneumatic, electrostatic, or electromagnetic forces to create a cushion on which the mover levitates. Magnetic levitation can be achieved by using permanent mag- nets, electromagnets, or diamagnetic bodies (a superconductor). The main advantage of the contact-free systems is low friction. The drawback of these systems is their high sensitivity to the cushion thickness (load dependent), while the cushion thickness can also be quite difficult to control. Also, this kind of con- veyance system often has low load capacity. Systems where the actuators are in contact with the moving object have been realized based on arrays of moveable legs erected from the silicon wafer surface. The legs have been actuated by using different principles such as thermal, electrostatic, and magnetic actuation. Both synchronous driving [Liu et al., 1995] and the more complex, but also more effective, asynchronous driving modes have been used. The magnetic [Nakazawa et al., 1997; 1999] and pneumatic [Hirata et al., 1998] actuation principles for contact-free conveyer systems have a disadvantage that they require a specially designed magnet mover or slider which limits the usefulness. With a contact system based on thermal actuators it is possi- ble to move objects of various kinds (nonmagnetic, nonconducting, unpatterned, unstructured, etc.); however, the increased temperature of the leg in contact with the conveyed object may be a limitation in some applications. The contact-free techniques have been developed mainly to meet the necessary crite- ria for a cleanroom environment, where a contact between the conveyer and the object may generate par- ticles that would then servetorestrict its applicability for conveyance in clean rooms. A microconveyer structure based on very robust polyimide V-groove actuators has been realized [Ebefors et al., 2000]. This conveyer is shown in Figure 7.14. In contrast to most of the previously presented Θ K T H - S 3 Cured polyimide Metal ∆x ∆z Leg position when heater "off" Leg position when heater "on" − Ground (a) Silicon leg Heating resistors Right forward, x + r Left forward, x + l Left forward, x − l Right backward, x − r FIGURE 7.14 (a) Principle for the rotational movements on a test conveyer using robust PVG joints. The left and right side can be actuated separately like a caterpillar. Each leg has a size of 500 ϫ 600 ϫ 30µm. (b) Photograph show- ing different (undiced) structures used to demonstrate the function of the polyimide-joint-based microconveyer. One conveyer consists of two rows of legs (12 silicon legs in total). Two sets of legs (six each of x ϩ and x Ϫ ) are indicated in the photograph (compare Figure 7.6c). For the conveyer with five bonding pads, the right and left rows of legs can be controlled separately for possible rotational conveyance. (c) SEM photographs showing Si legs with a length of 500 µm. (d) The microconveyer during a load test. The 2-g weight shown in the photograph is equivalent to 350 mg on each leg or 16,000 times the weight of the legs. (Note: Videos of various experiments involving this microconveyer are available at http://www.s3.kth.se/mst/research/gallery/conveyer.html/ or http://www.iop.org/Journals/jm.) © 2006 by Taylor & Francis Group, LLC microconveyance systems, the PVG joint approach has the advantage of producing robust actuators with high load capacity. Another attractive feature of this approach is the built-in self-assembly by which one avoids time-consuming manual erection of the conveyer legs out of plane. Some of the conveyers listed in Table 7.3 require special movers (e.g., magnets or sliders with accurate dimensions). The PVG joint con- veyer solution is more flexible because one can move flat objects of almost any material and shape. The large actuator displacement results in a fast system that is less sensitive to the surface roughness of the moving object. By using individually controlled heaters in each actuator, an efficient asynchronous driv- ing mode has been realized, which also allows a parallel design giving relatively high redundancy for actu- ator failure. The first experiments with the conveyer showed good performance, and one of the highest reported load capacities for MEMS-based microconveyers was obtained. The maximum load successfully conveyed on the structure had a weight of 3500mg and was placed on a 115-mg silicon mover, as shown in Figure 7.14d. Conveyance velocities up to 12 mm/s have been measured. Both forward–backward and simple rotational conveyance movements have been demonstrated. The principle for rotating an object by a two-row conveyer is shown in Figure 7.14a. The lifetime of the PVG joints actuator exceeds 2 ϫ 108 load cycles and so far no device has broken due to fatigue. The most sophisticated microrobotic device fabricated to date is the two-dimensional microconveyer system with integrated CMOS electronics for control which has been fabricated by Suh et al. (1999). The theories on programmable vector fields for advanced control of microconveyance systems presented by Böhringer et al. (1997) were tested on this conveyer. Several different versions of these conveyers have been fabricated throughout the years [Suh et al., 1997; 1999]. All versions are based on polyimide ther- mal bimorph ciliary microactuator arrays, as shown in Figure 7.15. 7-22 MEMS: Applications (b) (c) (d) Bonding pads 100 µm FIGURE 7.14 Continued. © 2006 by Taylor & Francis Group, LLC Microrobotics 7-23 Electrostatic plate Tip Low CTE polyimide Encapsulation stiffening layer (Curled out of plane when not heated) Base TiW resistor High CTE polyimide Wet Etch access vias (a) (b) Motion Motion News News News News Up (off) Down (on) North East West South Phase 1 Phase 2 Phase 3 Phase 4 (d) 1 2 3 4 (c) (e) (f) (g) (h) 370° 270° 135° 0° 300 µm FIGURE 7.15 (a) Principal of operation of an organic microactuator (bimorph polyimide legs) using thermal and electrostatic forces for actuation. Half of the upper polyimide and silicon nitride encapsulation/stiffening layer have been removed along the cilium’s axis of symmetry to show the feature details. (b) SEM photograph of a polyimide cilia motion pixel. Four actuators in a common center configuration make up a motion pixel. Each cilium is 430 µm long and bends up to 120 µm out of the plane. (c) Micro cilia device moving an ADXL50 accelerometer chip. (d) The CMS-principle for two-dimensional conveyance (compare Figure 7.6). The state of the four actuators (north, east, west, south) is encoded with small letters (e.g., n) for down, and capital letters (e.g., S) for up. (e)–(h) Images (video frames) of a 3 ϫ 3-mm 2 IC chip rotating from a rotation demonstration. (Printed with permission and courtesy of Suh, Böhringer and Kovacs, Stanford University.) © 2006 by Taylor & Francis Group, LLC [...]... June 16 19 , Chicago, USA Nakazawa, H., Wantanabe, Y., Morita, O., Edo, M., Yushina, M., and Yonezawa, E (19 99) “Electromagnetic Micro-Parts Conveyer with Coil-Diod Modules,” Tech Digest, 10 th Int Conf Solid-State Sensors and Actuators (Transducers ’99), pp 11 92 11 95, June 7 10 , Sendai, Japan Ok, J., Chu, M., and Kim, C.-J (19 99) “Pneumatically Driven Microcage for Micro-Objects in Biological Liquid,” The. .. Mechanismson-a-Chip Enabled by 5-Level Surface Micromachining,” The 10 th International Conference on Solid-State Sensors and Actuators (Transducers ’99), pp 990–993, June 7 10 , Sendai, Japan Ruffieux, D., and Rooij, N.F.d (19 99) “A 3-DOF Bimorph Actuator Array Capable of Locomotion,” The 13 th European Conference on Solid-State Transducers (Eurosensors XIII), pp 725–728, Sept 12 15 , The Hauge, The Netherlands... IEEE J MEMS, 1( 1 (March)), pp 44– 51 Frank, T (19 98) “Two-Axis Electrodynamic Micropositioning Devices,” J Micromech Microeng., 8, pp 11 4 11 8 Fujita, H., and Gabriel, K.J (19 91) “New Opportunities for Micro Actuators,” Tech Digest, 6th Int Conf Solid-State Sensors and Actuators (Transducers ’ 91) , June 24–27, pp 14 –20, San Francisco, CA, USA Fukuda, T., Kawamoto, A., Arai, F., and Matsuura, H (19 94) “Mechanism... Turbine/Bearing Rig,” The 12 th IEEE International Micro Electro Mechanical System Conference (MEMS ’99), pp 529–533, Jan 17 – 21, 19 99, Orlando, Florida, USA Lin, L.Y., Shen, J.L., Lee, S.S., and Wu, M.C (19 96) “Realization of Novel Monolithic Free-Space Optical Disk Pickup Heads by Surface Micromachining,” Opt Lett., vol 21( No 2 (January 15 )), pp 15 5 15 7 Liu, C., Tsao, T., Tai, Y.-C., and Ho, C.-H (19 94) “Surface... thick-film piezoelectric layers on top of each other with metal electrodes in between Because one layer is approximately 50 µm thick, a piezostructure for a 1- mm-long leg consists of several layers and electrodes, which require very high yield in the fabrication The metal electrodes are connected in parallel by the metal on the edges of the piezolegs to obtain higher redundancy for failure Besides the need... I (19 99) “Flight Performance of Micro-Wings Rotating in an Alternating Magnetic Field,” Proc of IEEE 12 th Int Conference on Micro Electro Mechanical Systems (MEMS ’99), pp 15 3 15 8, Jan 17 – 21, Orlando, USA © 2006 by Taylor & Francis Group, LLC 7-4 0 MEMS: Applications Miki, N., and Shimoyama, I (2000) “A Micro-Flight Mechanism with Rotational Wings,” The 13 th IEEE International Conference on Micro Electro... glass body [Simu and Johansson, 19 99] (see Figure 7.22) FIGURE 7 .17 Photograph of the microrobot platform, used for walking, during a load test The load of 2500 mg is equivalent to maximum 625 mg/leg (or more than 30 times the weight of the robot itself) The power supply is maintained through three 3 0- m-thin and 5- to 10 -cm-long bonding wires of gold The robot walks using the asynchronous ciliary motion... Buser, R (19 96) “Tactile Microgripper for Automated Handling of Microparts,” Sensors Actuators A, 53(Nos 1 4), pp 410 – 415 Greitmann, G., and Buser, R.A (19 96) “Tactile microgripper for Automated Handling of Microparts” Sensors Actuators A, 53 pp 410 – 415 Guckel, H., Klein, J., Christenson, T., Skrobis, K., Laudon, M., and Lovell, E (19 92) “Termo-Magnetic Metal Flexure Actuators,” Tech Digest, Solid-State... (19 99 (Sept 9)) “Unidirectional Rotary Motion in a Molecular System,” Nature, 4 01( 6749), pp 15 0 15 2 Kim, C.-J., Pisano, A., and Muller, R (19 92) “Silicon-Processed Overhanging Microgripper,” IEEE/ASME J MEMS, 1( 1), pp 31 36 Kim, Y.-K., Katsurai, M., and Fujita, H (19 90) “Fabrication and Testing of a Micro Superconducting Actuator Using the Meissner Effect,” Proc of IEEE 3rd Int Workshop on Micro Electro... Kimura, M., and Hasegawa, Y (19 99) “Micro Inspection Robot for 1- in Pipes,” IEEE/ASME Trans Mechatronics, 4(3 (September)), pp 286–292 Syms, R.R.A (19 98) “Rotational Self-Assembly of Complex Microstructures by the Surface Tension of Glass,” Sensors Actuators A, 65(Nos 2,3 (15 March 19 98)), pp 238–243 Syms, R.R.A (19 99) “Surface Tension Powered Self-Assembly of 3-D Micro-Optomechanical Structures,” J MEMS, . test. The load of 2500 mg is equivalent to maximum 625 mg/leg (or more than 30 times the weight of the robot itself). The power supply is maintained through three 3 0- m- thin and 5- to 10 -cm-long. commercially successful processes employed in Microrobotics 7-3 1 x − x + Bonding pad 15 mm 0.5 mm 5 mm Gold wire K T H - S 3 K T H - S 3 FIGURE 7.23 An upside-down view of the PVG joint-based microrobot. [Nakazawa electromagnets (unloaded) external load/ 1 ϫ 1 mm 2 /total et al., 19 97; 12 00 mg g area: 40 ϫ 40 mm 2 19 99] C: array of non-erected Not specified Not specified ∆x ϭ 10 m/ 12 5 triangular