In all of the actuating mechanisms for the precision positioning systems such as compliant, inertial, ultrasonic and inchworm, the lack of an integrated precision positioning system with high stroke and multi-axis operation is felt. In this paper, a state-of-the-art integrated two-axis inchworm piezomotor with an innovative operating principle is proposed. This piezomotor consists of two stages that are integrated, and each one delivers continuous motion in one-axis. Each of the stages consists of three actuating parts: two clamping actuators to engage/disengage with the guideway or frame (depend on the stage), and one feeder actuator to provide the stepby-step motion. The mode shapes and Von Mises stress distribution for each stage are analyzed by using the finite element analysis method. The performance of each stage is then verified throughout the experimental tests. The experimental tests are carried out to realize the two-axis piezomotor characteristics such as step pitch, resolution, axial speed, bearing capacity, and operating frequency in each stage.

In this paper, a nozzle-diffuser electromagnetic micropump with nanocomposite magnetic membrane for sub-microliter pumping applications is presented. The membrane included magnetite (Fe3O4) nanoparticles dispersed in a layer of polydimethylsiloxane (PDMS). Fe3O4 as a nontoxic and environmentally friendly material with excellent magnetic properties is used for the first time in the fabrication of an electromagnetic micropump. In order to achieve the most biocompatibility, PDMS is applied in most parts of the micropump. Lack of control on the recovery time of the membrane is one of the most important disadvantages of the proposed micropumps in the literature. This weakness causes an imbalance between the supply and pump mode of the micropumps leading to an undesirable performance of both of these. To address this issue, a bidirectional electromagnetic micropump is presented in this paper. In this system a secondary magnetic field is applied to equalize the response and recovery time of the membrane. Using this novel micropump, the maximum flow rate of 1.25 µl min−1 at the frequency of 0.1 Hz has been achieved. To indicate the best performance conditions for the micropump, effective parameters on the micropump performance were examined. These parameters include the size of the microchannels, electric current, number of coil turns, concentration of the Fe3O4 nanoparticles and frequency.

No abstract

No abstract

As a main component, membrane micropumps play a key role in developing microfluidic systems. This part pumps fluids by deflecting a membrane using a micro-actuator with a deflection range of a few micrometers during a few seconds. Most electromagnetic micropumps have low lifetime and fracture toughness or low recovery speed. Micropumps with metallic mass-spring structures can overcome the mentioned disadvantages or limitations. This study investigated the fabrication and characterization of a novel electromagnetic micropump. The proposed micropump consists of a stainless-steel mass-spring structure, a polydimethylsiloxane (PDMS) body and membrane, a permanent NdFeB magnet, a micro-coil, and a 3D printed spacer. To characterize the micropump, the effects of the frequency and duty cycle of the electric current applied to the micro-coil on the micropump flow rate and the membrane deflection vs. time were investigated. A membrane deflection of ±8 µm was obtained in 4 s by applying 1000 mA electrical current to the micro-coil. The maximum volumetric flow rate of 523 nL/s was obtained at a frequency of 125 mHz and a duty cycle of 50%. The von Mises stress distribution in the micropump membrane and variations of the fluid velocity in the microchannels were analyzed using the finite element method (FEM).