On-chip Robotics : Technical Issues and Future Direction

Micro-nano robotics plays an important role to supply advanced devices and equipments in Bio-medical engineering and science. There is an increasing interest in miniaturization and integration of functional devices by MEMS/NEMS technologies. Recent interest is in manipulation technology for works from millimeter to nanometer scale. These works contribute to elucidate the mechanism of the cell system, realize gene expression control, and automatic cloning on a chip. We have studied on robotic technology on a chip. Our concept is based on micro-nano robots or tools being put in the microchannel, where they are actuated and manipulated for works such as sensing, handling, surgery, and so on. A robot-on-a-chip (ROC) is a device that integrates one or several robotic functions on a single chip of only millimeters to a few square centimeters in size. This talk will provide our recent research works on On-chip Robotics[1]-[3]. Technical issues and future direction will be discussed. 1. On-chip Non-contact Manipulation by Magnetically Driven Microtool (MMT) 1.1. Cell Manipulation by Hybrid 2DOF-MMT The manipulation of cloning of cells and oocyte is mainly carried out by mechanical manipulator, however this method tends to have a risk of contamination, low repeatability and low success rate. To overcome such problems and to improve the efficiency of the operation, we are targeting the automation of the cloning technique. We have been developed MMT (Magnetically Driven Microtool) on a chip to achieve non-contact cell manipulation in a closed space [2],[3]. For the current study, we have developed hybrid type MMT. The hybrid MMT is the combination of polymer and Nickel. We have developed 2DOF (two degree of freedom) type (2DOF-MMT). By using the hybrid 2DOF-MMT, the cutting of oocyte was successfully operated and which contributes to the cell enucleation[4]. The drive unit of 2DOF-MMT was also improved by using the vibration of MMT by changing the density of magnetic flux of the electromagnetic coil and this technique successfully reduced the dead band of the magnetic actuation. 1.2 Actuation of 2DOF-MMT Figure 1 shows the concept view of a dual arm microrobot system on a chip for enucleation of oocyte. The 2DOF-MMT is located in the left and right hand side of the microchannel facing each other for the position of the oocyte. The height of the polymer part of 2DOF-MMT was 100 m and Ni part was 50 m. The microfluidic chip is composed of polydimethylsiloxane (PDMS) and the depth of the channel for the manipulation of oocyte was designed to be shallower (100 m) than the other region (200 m). This channel design has an advantage in the observation of nucleus of oocyte because the oocyte is easy to be deformed to be flat. Fig. 1. Concept of a dual arm microrobot system on a chip for enucleation of oocyte. 2DOF-MMT was fabricated by fitting of a Nickel part with a cutting function to the polymer part which is made of the mixture of magnetite (Fe3O4) and PDMS as shown in Figure 2. 2DOF-MMT is controlled by the permanent magnet attached to the micromanipulator. Speaker’s Photo