Hiroki Kuriki

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].

Simultaneous ablation and injection by electrically-induced mono-dispersed bubble knife for biomedical applications

For the present study, simultaneous ablation and injection was successfully operated by using electrically-induced micro-bubble knife for biomedical applications. The novelty of the present techniques are (1) dispensing of micro-bubble can penetrate and make an ablation of a cytomembrane and (2) the reagent was successfully introduced to the interface of the bubble surface. This technique has advantages over the conventional injection technologies such as electroporation or ultrasound operation in terms of localization of injection and ability of transportation.

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.

Electrically-induced bubble knife for protein crystallization and processing

We have succeeded in protein crystallization and processing by electrically-induced bubble knife. The dispensed directional mono-dispersed micro-bubbles whose air-liquid interface tends to combine the ambient molecules due to by their stiction force on the surface of micro-bubbles. Electrically-induced bubble knife enables to generate mono-dispersed micro-bubbles by the electrolysis and local heat, and their generation speed was 30.8 kHz. These characteristics enable to agglomerate the protein molecule which brings to successful protein crystallization in the solution with low concentration. The rate of protein crystal-nucleation by electrically-induced mono-dispersed micro-bubble was much higher than that of control condition. Furthermore, it was confirmed that cavitation induced by electrically-induced bubble knife enabled to curve protein crystal. It seemed that it has potential to contribute to more refined analysis.

Dispensing of mono-dispersed micro-bubbles for cell ablation

We have successfully produced mono-dispersed micro-gas bubbles for less than around 10 μm diameter by micro-bubble knife which produce micro-bubble in an electrically induced ultrasonic field. The discharged output power and conductive area of micro-electrode in micro-bubble knife which cuts the cell by micro-bubble were controlled by glass shell insulation around the copper micro-wire. A small space which is called “bubble reservoir” between the wire and glass tip contributes to stabilize the electric discharge and directional bubble generation. The directionally dispensed bubbles can be used for processing of soft materials such as biological cells. For the present study the cell membrane has successfully processed with a few μm order resolution.

Electrically induced bubble knife

We have successfully operated enucleation of oocyte by using micro-electric knife without any thermal collateral damage. Minimally-invasive cellular-scale ablation was achieved by the mono-dispersed micro-bubbles which were generated by a pulse discharge of micro-electrode. The discharged output power and conductive area of micro-electrode were controlled by glass shell insulation around the copper micro-wire. A small space which is called “bubble reservoir” between the wire and glass tip contributes to stabilize the electric discharge and directional bubble generation.

Local ablation by plasma blade using on-chip micro-electrode

For the present study, we propose local ablation using micro-electric knife technology. High current and voltage input was applied to the edge of electric knife whose conductive region was limited to the order of micron. The local ablation was carried out by discharging micro-plasma from the edge of the electric knife. Initial test of the local ablation on the oocyte in the medium showed that undesired bubble generation when the voltage was applied to the electrode, and which prevent observation with high resolution. Hence, the insulated layer was fabricated around the electrode to limit the conductive region. First test of the plasma blade show the red illuminated radiation at the tip of the electrode (1 W input) and the burned region was limited to about 10 µm. Expansion of the current proposed research will contribute to the cell surgery and to the field of gene engineering and developmental engineering And the proposed technology will contribute to the rapid progress of technological innovation of electric knife.