2023 Laser direct writing of conductive structures on hydrogels for supercapacitor fabrication
Direct writing of conductive structures by simple laser irradiation was demonstrated for the first time, and the presented method was applied for the fabrication of hydrogel-based supercapacitor. Hydrogels are widely used for biomedical products including contact lenses, owing to its high biocompatibility. The presented method realizes the facile fabrication of hydrogel-based electronic devices (e.g., smart contact lenses).
This paper has been published in Advanced Electronic Materials.
https://doi.org/10.1002/aelm.202201277
2022 Fabrication of Supercapacitor using Laser-induced Graphene Derived from Bamboo
Laser-induced graphene patterned on a renewable biomass resource, bamboo, was used as the electrodes of the supercapacitor. The proposed method allows for the fabrication of environmentally-friendly supercapacitors comprised of all renewable biomass resources.
This paper has been published in RSC Advances.
https://doi.org/10.1039/D2RA05641K
2021 The “Drawing” of Graphene Quantum Dots with a Laser
Quantum dots are nano-sized particles that exhibit photoluminescence owing to quantum
confinement effects and are desirable materials for applications such as light-emitting
diodes, biomarkers, and anticounterfeiting security tags. Particularly, GQDs have attracted
significant attention as an eco-friendly alternative to conventional QDs in the context of
sustainable development. In this work, it has been revealed that by irradiating and scanning
focused ultrashort laser pulses, GQDs can be simultaneously synthesized and patterned
along desired paths, similar to drawing with a pen. Since the presented method is based on
multiphoton interactions, GQDs can be patterned, not just two-dimensionally on the
surface, but three-dimensionally inside of the transparent polymer substrate. This work
expands the possibilities of GQDs for applications in novel flexible optoelectrical devices.
The paper has been published in Nano Letters.
https://pubs.acs.org/doi/10.1021/acs.nanolett.1c04295
2021 Laser-induced Graphitization of PDMS for Soft, Small, and Sensitive Pressure Sensors
Highly crystalline graphene was directly written onto the surface of native PDMS. Although most previous studies demonstrated the formation of laser-induced graphene (LIG) from polyimide, we demonstrated the formation of LIG from PDMS by
utilizing a femtosecond laser. Furthermore, by exploiting the elasticity of PDMS and the high conductivity of graphene, a small and highly sensitive pressure sensor was fabricated. Measurement of the heart rate from just the index finger
was demonstrated using the sensor.
The paper has been published in Advanced Engineering Materials.
https://doi.org/10.1002/adem.202100457
2021 Femtosecond Laser-Induced Graphitization of Transparent Cellulose Nanofiber Films
The fabrication of highly conductive graphitic carbon from cellulose nanofiber, a sustainable biomass, using a high-repetition femtosecond laser was demonstrated. The fabricated structures were composed of highly crystalline graphitic
carbon that exhibit a conductivity more than 100 times higher than the that reported previously. Our presented technique will contribute to realize sustainable electronic devices using mechanically robust and transparent CNF films.
This paper has been published in ACS Sustainable Chemistry & Engineering.
https://doi.org/10.1021/acssuschemeng.0c09153
2020 Synthesis of silicon carbide nanocrystals and multilayer graphitic carbon
Detailed analyses of femtosecond-laser-modified regions of native PDMS were performed. Micro- and nano-scale investigation of the laser irradiated areas revealed the formation of SiC nanocrystals, as well as multilayer graphitic carbon.
Furthermore, electrical conductivity measurements, in addition to Raman analyses, indicated that the formation of graphitic carbon contribute to the electrical conductivity of the structures.
The paper has been published in Nanoscale Advances.
https://pubs.rsc.org/en/content/articlelanding/2020/na/d0na00133c#!divAbstract
2020 Myoblast adhesion and proliferation on biodegradable polymer films with fs laser-fabricated micro through-holes
Acceleration of myoblast adhesion and proliferation were demonstrated by using micro through-holes fabricated by femtosecond laser processing. Cell differentiation was also accelerated along with the structures consisting of micro
through-holes. The fabrication of micro through-holes is a promising technique to control cell functions which is necessary for tissue engineering.
The paper has been published in Journal of Biophotonics.
https://doi.org/10.1002/jbio.202000037
2019 Laser direct writing of multi-metal microstructures inside a soft material
The spatially-targeted fabrication of bimetallic microstructure coexisting in the hydrogel is demonstrated by multi-photon photoreduction. The fabrication of dissimilar metal structures, that exhibit different optical properties, is a
promising technique for optically driven actuators in soft robotics and sensing applications. Formation of core-shell nanoparticles is also observed.
The paper has been published in Optics Express.
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-27-10-14657
2018 Femtosecond laser-based modification of PDMS to electrically conductive silicon carbide
We demonstrated the fabrication of conductive structures on the surface of polydimethylsiloxane (PDMS) by femtosecond laser direct modification of PDMS. Experimental results shown that the black structures were composed of SiC, which can
be attributed to the pyrolysis of the PDMS.
This research has been published in Nanomaterials.
http://www.mdpi.com/2079-4991/8/7/558
2018 Fabrication of stretchable wire grating inside hydrogel
We have demonstrated the fabrication of metal gratings inside a hydrogel by using femtosecond laser.
The grating period changed when the hydrogel shrank owing to the loss of water, which provides tunable optical properties of the metal structures.
The results show the potential of the present method for realizing novel sensors and optical devices.
The paper has been published in Scientific Reports.
https://www.nature.com/articles/s41598-017-17636-z
2017 Fabrication of PDMS/metal composite line structures for mechanical sensing
We fabricated composite line structures composed of PDMS and metal by femtosecond-laser-induced photopolymerization and photoreduction.
And, we demonstrated highly sensitive mechanical sensing by using the fabricated line structures.
The paper has been published in Optical Material Express.
https://www.osapublishing.org/ome/abstract.cfm?URI=ome-7-11-4203
The work appeared and was highlighted in following news release and websites.
http://www.osa.org/en-us/about_osa/newsroom/news_releases/2017/metal-silicone_microstructures_could_enable_new_ty
https://www.sciencedaily.com/releases/2017/11/171101122438.htm
http://www.sciencenewsline.com/news/2017110115590085.html
https://phys.org/news/2017-11-metal-silicone-microstructures-enable-flexible-optical.html
2017 Gold grating structures on fused silica substrate
We demonstrated the fabrication of GOLD periodic nanowire gratings by femtosecond laser irradiation to a gold thin film on a glass substrate.
Fabrication of the gold periodic nanostructures, which had been difficult to be formed, would contribute for development of various applications as well as elucidating the formation mechanism.
This paper has been published in Journal of Applied Physics.
http://aip.scitation.org/doi/full/10.1063/1.4982759
2017 Intracellular localization and delivery of plasmid DNA
We have demonstrated plasmid DNA/liposome complexes into cells by utilizing dielectric microspheres and a femtosecond laser.
The localization of Plasmid DNA in a cell was investigated with discussion on perforations of cell membrane as well as nuclear membrane.
The paper has been published in Journal of Biomedical Optics.
http://onlinelibrary.wiley.com/doi/10.1002/jbio.201600323/abstract;jsessionid=A9576960AC3F80AFD26272D7FAED80D9.f03t01
2016 Laser-triggered release of encapsulated molecules from biodegradable microcapsules
We demonstrated the release of encapsulated molecules from biodegradable polymer-based microcapsules using near-infrared femtosecond laser pulses.
The laser-induced modification of the surface of the shell of the microcapsules indicated the potential for sustained release as well as burst release.
The paper has been published in Journal of Biomedical Optics.
http://biomedicaloptics.spiedigitallibrary.org/article.aspx?articleid=2546591
2016 Modification of biodegradability of biodegradable polymer by femtosecond laser irradiation
The degradation rate of biodegradable polymer irradiated with UV laser wavelength was faster than that of the sample irradiated
with IR laser wavelength, suggesting the controllability of degradation rate after laser processing.
This method can be applicable to the fields of tissue scaffolding and drug delivery system.
This paper has been published in Scientific Reports.
http://www.nature.com/articles/srep27884
2016 Molecular delivery to flowing cells in microfluidic platform
The delivery of molecules into suspended-flowing cells in a microfluidic channel is demonstrated by using biodegradable polymer microspheres and a near-infrared femtosecond laser pulse.
In case of flowing cells, the number of fluorescence molecules observed in not only cytoplasm but also nucleus was higher compared to the case adhered cells.
In the future, our results show the potential of gene transfection to bone marrow transplantation and immune cells therapy.
The paper has been published in Journal of Biomedical Optics.
http://biomedicaloptics.spiedigitallibrary.org/article.aspx?articleid=2522081
2016 Fabrication of metal microstructure inside hydrogel
We have demonstrated the fabrication of metal microstructures in a synthetic polymer-based hydrogel by using femtosecond laser.
Shrinking and swelling of the fabricated structure is also demonstrated,
which shows the potential of the present method for realizing 3D flexible/optical devices.
The paper has been published in Optics Letters.
https://www.osapublishing.org/ol/abstract.cfm?uri=ol-41-7-1392
