Kazuhisa Onda

Multi-beam bilateral teleoperation of holographic optical tweezers

A multi-beam bilateral teleoperation system of holographic optical tweezers accelerated by a graphics processing unit is proposed and evaluated. This double-arm teleoperation system is composed of two haptic devices and two laser-trapped micro-beads. Each micro-bead is trapped and moved following the trajectory of each haptic device, and the forces to which the micro-beads are subjected, which are generated by Stokes drag, are measured and fed back to an operator via the haptic devices. This real-time telexistence was quantitatively evaluated based on the time response of the trapped beads and the fed-back forces. And the demonstration of touching red blood cells shows the effectiveness of this system for biomedical application.

Multi-beam laser micromanipulation of microtool by integrated optical tweezers

In noncontact cell manipulation with optical tweezers, we need to use microtools to avoid damages to the cells by direct laser irradiation. When we manipulate complex structures such as microtools, a multi-beam optical tweezers which can manipulate multiple objects is suitable; however manipulation speed or trapping number are not so good. Therefore, we developed an integrated optical tweezers by using time-shared scanning method for high speed manipulation and generalized phase contrast method for a lot of trapping. Then, we proposed cell manipulation method which suits for the integrated optical tweezers and then we designed the shape of microtools made of SU-8. A new fabrication method of SU-8 microtools was proposed to improve productivity. At last, we made the experiment system and the effectiveness of proposed methods was confirmed.

Massive parallel assembly of microbeads for fabrication of microtools having spherical structure and powerful laser manipulation

Production of functional microtools having an arbitrary shape by self-assembly of microparticles and heat treatment above the glass transition temperature of the microparticles was developed. Polystyrene microbeads were used as a material of the microtool. A solution including microparticles was dispersed onto the silicon substrate having microtool patterns fabricated by photolithography and etching. Dispersed particles were introduced to the pattern by gravity force. Microparticles in the pattern aggregate autonomously by surface tension through evaporation of the solution. Aggregated microparticles were fused by heating above the glass transition temperature (100 Celsius degrees). Fused microparticles were detached from the pattern by ultrasonic treatment and used as microtools. Produced microtool has spherical part since the microtool is made of microparticles. Spherical part is suitable for trapping point of optical tweezers. We demonstrated production of microtools using self-assembly and manipulation of the fabricated microtool on a chip. Position and attitude accuracy of the fabricated microtool controlled by TSS were evaluated by image processing. Finally, the transport speed of the fabricated microtool was compared with that of the photofabricated microtool. We confirmed the improvement of the transport speed and the effectiveness of our proposed microtool.

Parallel teleoperation of holographic optical tweezers using multi-touch user interface

Holographic optical tweezers (HOT) has ability to trap and manipulate a few hundred of small particles. Previously the manipulation speed is greatly limited to the calculation speed of holograms. But recent progress in parallel computing made it possible to generate the holograms in real-time. Therefore, HOT is thought to play an important role in dexterous micromanipulation. In practical application, the teleoperation of HOT is thought to improve the manipulability. But, the maximum number of objects which can be manipulated at once is limited by the master devices. In this research, we applied a multi-touch user interface for the master. And we designed and constructed the HOT teleoperation system. In the optical system, we implemented a zero-order beam filtering system to avoid the disturbance. In control system, we applied an Apple iPad2 as a master device. The design and the processing of the interface were proposed and discussed in consideration of the manipulability. And, we discuss the manipulation method making the best use of multi-touch user interface. With the constructed system, we demonstrated the parallel teleoperation of 10 particles. And the time response of manipulation shows the potential of smooth manipulation. Based on these discussions, we concluded that the constructed system is effective for micromanipulation.

3D fabrication and manipulation of hybrid nanorobots by laser

We developed fabrication and manipulation of hybrid nanorobots by 3D nano exposure and optical tweezers. Hybrid nanorobot is composed of photoresist and silicon nanowire. The robot is fabricated by femtosecond laser exposure and is connected to the glass substrate by a micropillar. The processing resolutions of the femtosecond laser exposure are 270 nm (line width) and 600 nm (thickness), respectively. The robot is released by cutting of the pillar by ablation with femtosecond laser. Release time is within four minutes. The released robot is manipulated by holographic optical tweezers (HOT). We succeeded in high-speed manipulation of the robot using HOT (transport speed: 100 μm/s, rotation speed: 1140 deg/s). The robot can be fabricated by incorporating temperature indicator to the robot body and inserting a silicon nanowire to the probe. The robot can be used as a thermal sensor by measuring temperature change from the probe to the robot body because silicon nanowire has high thermal conductivity (168 W/m·K). In this paper, we demonstrated fabrication, on-demand release, and manipulation of the robot in a solution. We also demonstrated temperature calibration and measurement to confirm the effectiveness of the temperature sensor.

Local ablation by micro-electric knife

We have firstly succeeded in enucleation of oocyte by using micro-electric knife. The discharged output power and conductive area were controlled to adapt the cellular-order ablation under water and under atmospheric pressure environment. The local area ablation was obtained by the glass shell insulation around the copper wire with silver paste, and which prevent the bubble generation when it was discharged under the water. This fabricated sharp electric knife has a designed small space at the end of the knife between the wire and the glass tip, and which contribute to stabilize the electric discharge. The width of the ablation region was successfully reduced to more than a half compare to the conventional wire electrode, by using the robust glass shell insulation and a single micro-scale bubble injected from inside of the electrode. Moreover, the nucleus dyed by Hoechst was also removed successfully with limited damage region which is the difficult task for manual operation with glass capillary. This low cost micro-electric knife can fabricate any objective material under various environments and it has a possibility to contribute to a new fabrication method in micro-nano bioengineering field.

Local Ablation by a Microelectric Knife: Enucleation of an Oocyte

The electric knife is one of the indispensable surgical devices widely used in surgical operation. However, it has not been remarkably improved since its invention several decades ago. For example, thermal damage of the current radiofrequency electric knife, which is one of the most nonintrusive type of electric knives, is more than several hundred micrometers. A laser device, which was invented approximately 70 years ago, has been developed remarkably, and various research report the interaction between the cells and laser to fulfill the cellular-order ablation [1], [2].

Robotic approach to multi-beam optical tweezers with Computer Generated Hologram

Multi-beam optical tweezers is important technique to manipulate multiple small objects. Computer Generated Hologram (CGH) is one of the techniques and it can trap more than 200 objects in three dimension. For dexterous micromanipulation, it is useful to apply robotics into optical tweezers. In this research, we designed the optical system and control system of Holographic Optical Tweezers (HOT). For optical design, we considered working space and positioning resolution. For control design, we applied teleoperation. For online generation of hologram, we developed GCH generator applied General-purpose GPU (GPGPU) acceleration. This system achieved high-speed generation of hologram (250 Hz). For full automatic control, we applied stability control theory to the multi-beam control system. With the built system, the positioning precision and response were revealed with trajectory control and teleoperation experiments. As the result, we checked the effectiveness of HOT enhanced by robotics.

Powerful Actuation of Magnetized Microtool by Focused Magnetic Field on a Disposable Microfluidic Chip

We succeeded in powerful noncontact actuation of magnetically driven microtool (MMT) by magnetizing it and focusing magnetic field in a microfluidic chip. Novelty of this paper is summarized as follows. (1) We employed neodium powder as the main component of MMT. The density of magnetic flux was improved about 100 times larger after magnetization. (2) We fabricated a pair of magnetic sharp needles in the chip by electroplating. MMT was placed between the needles and the density of magnetic flux was improved about 3 times larger. As a result, we succeeded in powerful actuation of MMT in the chip. Drive frequency was improved about 10 times faster (up to 180Hz).

Electric knife for cell surgery: Local ablation by micro-plasma discharge

We have firstly succeeded in enucleation of oocyte by using micro-electric knife. The discharged output power and conductive area were controlled to adapt the cellular-order ablation under water and under atmospheric pressure environment. The local area ablation was obtained by the glass shell insulation around the copper wire with silver paste, and which prevent the bubble generation and protein contamination when it was discharged under the water. The width of the ablation region was successfully reduced to more than a half by using the glass shell insulation compare to the conventional electrode. Moreover, the nucleus dyed by Hoechst was also removed successfully with limited damage region which is the difficult task for manual operation with glass capillary. This low cost micro-electric knife has a possibility to extend to fabricate any objective material under various environments and contribute to a new top-down fabrication method in the micro-nano bioengineering field.