Microactuators, design

Silicon micropumps offer major advantages in terms of system miniaturization and control over low flow rates with a stroke volume 160 nL.14 The micropump has the characteristics of very small in size, implantability in the human body, low flow rates (in the range of 10 pL/min), moderate pressure generation from the microactuator to move the drug, biocompatibility, and most important, a reliable design for safe operation. The implantable device is particularly suitable (over the injectable drug delivery systems) for patients with Parkinson s disease, Alzhiemer s disease, diabetes, and cancer, as well as chronically ill patients, because the catheter that is attached to the device can transport drug to the required site. 

Figure 4 The design of the implantable drug delivery system based on shape memory alloy microactuation, showing the main reservoir, pressure chamber, and the printed circuit board (PCB) with electronics and valve system. The basic concept is to have a reservoir under constant pressure pushing liquid through a calibrated flow channel and valve system. Dimensions are 50 mm with a height of 15 mm. Source From Ref. 36.

Finally, significant improvements in the field of giant magnetostrictions have allowed the design and test of some prototypes of microactuators and motors taking advantage of a wireless magnetic excitation. 

The electrothermal effects can also be exploited to design efficient microactuators, as... 

Novel designs of microfluidic systems and future lab-on-a-chip (LOG) devices (e.g., microvalves, micromixers, microactuators, etc.) can be introduced based on the behavior of conductivity of the surfaces using induced-charge electrokinetic phenomena. 

The schematic of one of the first ETC microactuators introduced in Guckel et al. (1992) is shown in Eigure 2.4. The thin arm (hot-beam) has a higher electrical resistance than the wide arm (cold-beam), gets heated more and consequently elongates more. Similar design models have... 

Lazarou, P. and Aspragathos, N.A. (2009) An integrated mechatronic approach for the systematic design of force fields and programming of microactuator arrays for micropart manipulation . Journal of Mechatronics, 19(3) 287-303. 

The small size and fact that they can operate in a liquid environment make CP microactuators interesting for applications in microfluidics and drug delivery. The CP-actuated valves can be designed using different mechanical principles such as bilayer hinges, buckling actuators, and bulk-swelling layers. 

Uroetani and Suzuki [37] described the design and fabrication of some piezoelectric polymer actuators for ipMial applkatioos. In particular, a composite micromanipulator, illustrated in Fig. 4. hM been realized using some bimorph PVDF dements. The microactuator assembly has three degrees of freedom and a gripper end. which is aUc lo grasp and position small objects within a volume of 330 X SOO X 150 un. Such structures, with linear dimensions ot few centimeters, can easily be used on the deck of a microscope. 

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