Jong Oh Park

Recognizing and tracking of 3D-shaped micro parts using multiple visions for micromanipulation

Presents a visual feedback system that controls a micromanipulator using multiple microscopic vision information. The micromanipulation stations basically have an optical microscope. However the single field-of-view of optical microscope essentially limits the workspace of the micromanipulator and low depth-of-field makes it difficult to handle 3D-shaped micro objects. The system consists of a stereoscopic microscope, three CCD cameras, the micromanipulator and personal computer. The use of a stereoscopic microscope which has long working distance and high depth-of-field with selective field-of-view improves the recognizability of 3D-shaped micro objects and provides a method for overcoming several essential limitations in micromanipulation. Thus, visual feedback information is very important in handling micro objects for overcoming those limitations and provides a mean for the closed-loop operation. We propose this method for recognition and tracking of 3D-shaped micro parts and generating motion commands for the micromanipulator.

Flexible microassembly system based on hybrid manipulation scheme

In this paper, a flexible microassembly system based on hybrid manipulation scheme is proposed and applied to the assembly of a photonic component. In order to achieve both high precision and dexterity in microassembly, we propose a hybrid microassembly system with sensory feedbacks of vision and force. This system consists of the distributed 6-DOF micromanipulation units, the stereo microscope, and haptic interface for the force feedback-based microassembly. A hybrid assembly method, which combines the vision-based microassembly and the scaled teleoperated microassembly with force feedback, is proposed. The feasibility of the proposed method is investigated via experimental studies for assembly micro opto-electrical components. Experimental results show that the hybrid microassembly system is feasible for applications to the assembly of photonic components in the commercial market with better flexibility and efficiency.

Implementation of a Piezoresistive MEMS Cantilever for Nanoscale Force Measurement in Micro/Nano Robotic Applications

The nanoscale sensing and manipulation have become a challenging issue in micro/nanorobotic applications. In particular, a feedback sensor-based manipulation is necessary for realizing an efficient and reliable handling of particles under uncertain environment in a micro/ nano scale. This paper presents a piezoresistive MEMS cantilever for nanoscale force measurement in microrobotics. A piezoresistive MEMS cantilever enables sensing of gripping and contact forces in nanonewton resolution by measuring changes in the stress-induced electrical resistances. The calibration of a piezoresistive MEMS cantilever is experimentally carried out. In addition, as part of the work on nanomanipulation with a piezoresistive MEMS cantilever, the analysis on the interaction forces between a tip and a material, and the associated manipulation strategies are investigated. Experiments and simulations show that a piezoresistive MEMS cantilever integrated into a microrobotic system can be effectively used in nanoscale force measurements and a sensor-based manipulation.

Tadpole robot (TadRob) using ionic polymer metal composite (IPMC) actuator

We have developed the wireless tadpole robot that has simple geometry, driven by low voltage and the undulatory fin-motion using IPMC(Ionic Polymer Metal Composite) actuator. Behavior of TadRob is tested under various frequencies(1~8Hz) to find the correlation between actuator frequency and velocity of the robot. In addition, the robot velocity according to undulation motion and oscillation motion of the fin is compared to find the proper fin-motion to increase the efficiency of the robot. Also, steering capability is tested under variation of duty ratio. Based on experimental results, we can confirm that the velocity of TadRob can be controlled by changing frequency of input voltage and the steering angle can be increased with increasing the duty ratio.

Innovation ultra thin packaging for RF-MEMS devices

In this paper, we report a novel RF-MEMS packaging technology with lightweight, small size, and short electric path length. To achieve this goal, we used the ultra thin silicon substrate as a packaging substrate. The via holes for vertical feed-through were fabricated on the thin silicon wafer by wet chemical processing. Then, via holes were filled and micro-bumps were fabricated by electroplating. To make up hermetic sealing, metal bonding (Au/Sn-Au) was used in the sealing line. Bonding strength after dipping in the water was about 60Mpa and there was no change. The packaged RF device has a reflection loss under -19 [dB] and a insertion loss of -0.54/spl sim/-0.67 [dB]. These measurements show that we could package the RF device without loss and interference by using the vertical feed-through. Specially, with the ultra thin silicon wafer we can realize of a device package that has low-cost, lightweight and small size. Also, we can extend a 3-D packaging structure by stacking assembled thin packages.

Multiple magnification images based micropositioning for 3D micro assembly

This paper presents micropositioning system using feedback of multiple magnification images from CCD cameras mounted on an optical microscope. In order to guarantee of the accurate micropositioning to micro assembly system, high precise sensors are required. But many kinds of sensors, which are used in macro world, have insufficient resolution and size. The visual data from an optical microscope have vast information, however, the single field-of-view of optical microscope essentially limits the workspace of the micromanipulator and the low depth-of-field makes it difficult to handle micro parts. To overcome these problems and increase and precision of micropositioning system, we use multiple magnification images that have same viewpoint. The use of multiple magnification images reduces the time consuming for handling of micro parts and increases precision of micropositioning. We propose this method for micropositioning system.

Advanced controller design and implementation of a sensorized microgripper for micromanipulation

This paper presents the design, and control of a sensorized microgripper using VCM (voice coil motor). In order to increase the sensitivity of the sensorized microgripper, shape design and determination of sensor position are performed using finite element analysis. Micro EDM (electric discharge machine) and wire cutting technique are employed to fabricate the microgripper. Empirical model of the microgripper is achieved to analyze the performance and to control the position and gripping force. By using this identification model, both the perfect tracking controller (PTC) for the position control, and the adaptive zero-phase error tracking controller (ZPETC) for the force control are implemented. The effectiveness of the proposed model-based control method is verified by both simulation and experimental studies. Simulation and experimental results show that the proposed control method can be effectively applied to improve the motion tracking performance. Especially, in case of force control to grip and manipulate soft materials such as biomaterials and tissues, the proposed controller can be very useful to prevent the invasion of the target material by excessive force.

A novel thin chip scale packaging of the RF-MEMS devices using ultra thin silicon

In this paper, as ultra thin silicon substrate was used as packaging substrate, we proposed ultra thin chip size RF-MEMS packaging technology that has vertical feed-through for low loss, as reduced the parasitic capacity. Thin silicon wafer with 50um thickness was fabricated to achieve short electric path, low loss and lightweight. And then via holes with the diameter of 60um were fabricated and was filled by the RIE and electroplating process. Also, the wafer level bumps were fabricated for simple, low cost, and fine patterning process. The measured S-parameter of packaged CPW(Co-planner waveguide) has the reflection loss of under -19 dB and the insertion loss of -0.54 to -0.67 dB.

A miniaturized fluorescence detection system with an integrated organic light emitting diode

The organic light emitting diode (OLED) is proposed as a novel source in the microchip because it has ideal merits (various wavelengths, thin-film structure and overall emitting) for the integration. In this paper, we fabricated finger-type PIN photodiodes for the fluorescence detection and an advanced microchip with an integrated OLED. The finger-type in the diode design extended the depletion region and its internal resistance was reduced about 32% than that of a rectangular-type. The photodiodes had 0.1 nA leakage current and 8,720 sensitivity (I/sub light//I/sub dark/) at -1 V bias. The interference filter with 32 layers (SiO/sub 2/, TiO/sub 2/) was directly deposited on the photodiode. Deposited OLEDs increased the excitation efficiency and extremely simplified the integration process. The monolithically integrated microchip had a high sensitivity of 0.256 nA//spl mu/M and the LOD (limit of detection, S/N =2) of 0.01 /spl mu/M.