| 1. |
Droplet-based microfluidic sensing system for rapid fish freshness determination
A microfluidic device was constructed for on-site determination of fish freshness by using adenosine-5′-triphosphate (ATP) concentration as an indicator of freshness. In the device, extracts from fish and reagent solutions were processed in the form of droplets separated by air. The volumes of the droplets of the extract solution, a solution containing enzyme substrates, and a washing buffer solution were measured in branched flow channels. To simplify the structure and procedure for mixing solutions, a wider portion was formed in one flow channel to merge the droplets. A row of droplets was ejected from each of three branched flow channels, merged in the wider portion, and transported to a sensing region located downstream. ATP was detected using two enzymatic reactions involving glycerol kinase (GK) and glycerol-3-phosphate oxidase (G3PO). A linear relationship between the generated current and ATP concentration was confirmed, and ATP detection from jack mackerel extracts was carried out. A distinct change in the current was observed with the fresh extracts as in the case of standard solutions. The obtained data correlated well with those obtained by high-performance liquid chromatography (HPLC). © 2012 Elsevier B.V. All rights reserved.. |
| 2. |
Odorants measurement using hyperspectral imaging and PVC film including multi fluorescent probes
Odor imaging sensor was developed with odorants sensing mechanism based on the complicated fluorescence interactions between the multi-fluorescent-probes and odorants. In this research, poly vinyl chloride (PVC) films including various fluorescent probe were developed, and fluorescence properties of the film were investigated. Using the multi fluorescent probe film, fluorescence intensity change spectrum to various odorants was measured, and odorants could be clustered by their chemical structure by multi-variate analyses of hyper spectra images.. |
| 3. |
Probe gas sensing system based on reflected light detection from localized surface plasmon resonance
The present study explored a probe type gas detection system which can be used to detect the gas conveniently. The gas sensing mechanism is utilizing Localized Surface Plasmon Resonance (LSPR) sensor which based on the reflected light change caused by the refractive index changes of gas where exposing to the metal nanoparticles layer. The LSPR layer was prepared by vacuum sputtering of AuNPs on a glass substrate, growing in silver growth solution and consequently thermal annealing. An optical system which composed of fiber probe, light source and spectrometer was developed to detect the change of reflected light. It was found that compared with incident light irradiating from metal nanoparticles side, glass side could obtain clearer spectra peak. In addition, a LSPR sensor which had 5 hours silver growth time has the best response to acetic acid gas. This work demonstrated that the reflection detection system has a great potential in gas detecting area.. |
| 4. |
Odor Trace Visualization by Mobile Robot Equipped with Two-Dimensional LSPR Gas Sensor
This paper presents a Localized Surface Plasmon Resonance (LSPR) based high speed gas sensor module for gas sensing applications, including visualization of invisible odor trail. Innovative claims include: (1) the use of a double layer film with Au/Ag nanoparticles for gas detection; (2) high speed response characteristic; and (3) visualization of odor trail pattern with high spatial resolution. The results show a significant change in reflection light with ethanol vapor; response speed of 1 second; and a clear image of visualized odor trail of letter "Q" of a 3 mm line width.. |
| 5. |
Invisible Odor Trace Tracking with LSPR based High Speed Gas Sensor Robot System
Various odor robots have been developed for finding gas sources. However, the response speed of sensors is now a major limit for the promotion of odor robot using chemical substances information. In this research, we have developed a robot equipped with two LSPR (Localized Surface Plasmon Resonance) gas sensor module that can quickly respond to gas molecules at a high speed of above 25 Hz and set a specific algorithm for tracking the invisible odor line on the ground.. |
| 6. |
Gas Visualization with Photo-Induced 2D Pixel Patterned Au/Ag Core-Shell LSPR Imaging Device by Mask-Less Exposure System
Visualization of the distribution of various gases makes us possible to recognize environmental circumstances, e.g., localization of dangerous chemical sources or human body odorants in the case of disaster scene. Localized surface plasmon resonance (LSPR) can detect various gases with changes of surrounding dielectric constant, and can be used gas sensor with high response / recovery speed and high spatial resolution, i.e., 2 dimensional LSPR gas sensor gas work as a gas image sensor device. The gas image sensor detects the gas distribution occurred on the LSPR substrate by an ordinal image sensor. The general LSPR gas sensor, however, does not have a molecular selectivity, then the identification of gas species is difficult. To overcome such disadvantages, pixelated LSPR substrate based on Au/Ag core-shell structure is fabricated by photo-induced growth by mask-less exposure system using a commercial video projector.. |
| 7. |
2D LSPR multi gas sensor array with 4-segmented subpixel using Au/Ag core shell structure
LSPR (Localized Surface Plasmon Resonance) based 2D (2 Dimensional) gas imaging sensor system which can capture spatial distribution of each constituent of mixed gas have been developed. The gas image sensor detects the gas promoted optical changes occurred on the LSPR substrate by CCD camera. Basically, LSPR gas sensor does not have a molecular selectivity, then the identification of gas species is difficult. To overcome the disadvantage, pixelated LSPR substrate based on Au/Ag core-shell structure which has different gas response properties is fabricated by photo-induced metal growth by mask-less exposure system using a commercial video projector.. |
| 8. |
Lin Chen, Hao Guo, Fumihiro Sassa, Bin Chen, Kenshi Hayashi, Sers gas sensors based on multiple polymer films with high design flexibility for gas recognition, Sensors, 10.3390/s21165546, 21, 16, 2021.08, The Surface-Enhanced Raman Scattering (SERS) technique is utilized to fabricate sensors for gas detection due to its rapid detection speed and high sensitivity. However, gases with similar molecular structures are difficult to directly discriminate using SERS gas sensors because there are characteristic peak overlaps in the Raman spectra. Here, we proposed a multiple SERS gas sensor matrix via a spin-coating functional polymer to enhance the gas recognition capability. Poly (acrylic acid) (PAA), Poly (methyl methacrylate) (PMMA) and Polydimethylsiloxane (PDMS) were employed to fabricate the polymer film. The high design flexibility of the two-layer film was realized by the layer-by-layer method with 2 one-layer films. The SERS gas sensor coated by different polymer films showed a distinct affinity to target gases. The principle component analysis (PCA) algorithm was used for the further clustering of gas molecules. Three target gases, phenethyl alcohol, acetophenone and anethole, were perfectly discriminated, as the characteristic variables in the response matrix constructed by the combination of gas responses obtained 3 one-layer and 3 two-layer film-coated sensors. This research provides a new SERS sensing approach for recognizing gases with similar molecular structures.. |
| 9. |
C. Duran, S. Zhang, C. Yang, M. L. Falco, C. Cravo-Laureau, C. Suzuki-Minakuchi, H. Nojiri, R. Duran, F. Sassa, Low-cost gel-filled microwell array device for screening marine microbial consortium, Frontiers in Microbiology, vol.13, 1031439, 2022.12. |
| 10. |
Shiyi Zhang, Joseph Wang, Kenshi Hayashi, Fumihiro Sassa, Monolithic processing of a layered flexible robotic actuator film for kinetic electronics, SCIENTIFIC REPORTS, 10.1038/s41598-021-99500-9, 11, 1, 20015-20015, 2021.10, Low-invasive soft robotic techniques can potentially be used for developing next-generation body-machine interfaces. Most soft robots require complicated fabrication processes involving 3D printing and bonding/assembling. In this letter, we describe a monolithic soft microrobot fabrication process for the mass production of soft film robots with a complex structure by simple 2D processing of a robotic actuator film. The 45 mu g/mm(2) lightweight film robot can be driven at a voltage of CMOS compatible 5 V with 0.15 mm(-1) large curvature changes; it can generate a force 5.7 times greater than its self-weight. In a durability test, actuation could be carried out over 8000 times without degradation. To further demonstrate this technique, three types of film robots with multiple degrees of freedom and a moving illuminator robot were fabricated. This technique can easily integrate various electrical circuits developed in the past to robotic systems and can be used for developing advanced wearable sensing devices; it can be called "Kinetic electronics".. |
| 11. |
Ryosuke Nakai, Hiroyuki Kusada, Fumihiro Sassa, Susumu Morigasaki, Hisayoshi Hayashi, Naoki Takaya, Hideyuki Tamaki, Draft genome sequence of novel filterable rhodospirillales bacterium strain tmpk1, isolated from soil, Microbiology Resource Announcements, 10.1128/MRA.00393-21, 10, 28, e0039321, 2021.07, We report the draft genome sequence of novel Rhodospirillales bacterium strain TMPK1, isolated from a micropore-filtered soil suspension. This strain has a genome of 4,249,070 bp, comprising 4,151 protein-coding sequences. The genome sequence data further suggest that strain TMPK1 is an alphaproteobacterium capable of carotenoid production.. |
| 12. |
Chemiresistor sensor matrix prepared by full-printing processes
Herein, we report a novel full printing process for fabricating chemiresistor gas sensor matrixes on photographic paper with an inkjet printer. Sensor matrices, which can increase a number of sensors significantly compared to a serial sensor array, were printed on one piece of A4 photographic paper. Each sensor matrix contains 36 interdigital electrodes in an area of less than 11 mm2, which greatly improves the density of the sensor. The basic architecture of the sensor matrix is electrodes that row and column intersecting. In order to insulate the row and column electrodes from meeting each other, an insulating layer needs to be fabricated at the point of intersection between the row and column electrodes. The insulation layer was produced by adjusting the number of printing passes and shape of the printing pattern of color pigment ink. Carbon black (CB) was used to form a chemosensitive composite by changing its resistivity with a specific polymer for the preparation of sensing material. In order to make the sensing material can be printed, it is necessary to disperse CB first. CB was dispersed in aqueous solution with sodium dodecyl sulfate added as a surfactant to lower the surface tension, which enabled printing of CB using an inkjet printer. Some polymers have certain adsorption characteristics for gases. According to the different gas properties, the adsorption characteristics are also different. By adding polyethylene glycol polymer to the CB layer, the response to four gases with different properties is improved. Compared with the drop coating, the full-printing sensors not only reduces the production time significantly, but also improves the gas response magnitude to ethanol by about three times. The results demonstrate that the developed sensor can be used as a low cost, disposable, and easily printable chemical sensor.. |
| 13. |
2D LSPR gas sensor with Au/Ag core-shell structure coated by fluorescent dyes
LSPR (Localized Surface Plasmon Resonance) based 2D (Two-dimensional) gas sensor system which can measure and identify multi-gases with high spatial resolution have been developed. The gas sensor detects optical changes promoted by the gas on the LSPR substrate with hyperspectral camera. Basically, LSPR gas sensor does not have a molecular selectivity, then the identification of gas species is difficult. To overcome the disadvantage, LSPR substrates based on Au/Ag core-shell structure with spectral gas-discriminating ability through optical interaction were fabricated by spin coating fluorescent dyes. Using the LSPR coupled with fluorescent dyes, this sensor provides rich spectral information about the detecting molecules and can discriminates gas species.. |
| 14. |
Fumihiro Sassa, Gokul Chandra Biswas, Hiroaki Suzuki, Microfabricated electrochemical sensing devices, Lab on a Chip, 10.1039/c9lc01112a, 20, 8, 1358-1389, 2020.04, Electrochemistry provides possibilities to realize smart microdevices of the next generation with high functionalities.. |
| 15. |
Zhongyuan Yang, Fumihiro Sassa, Kenshi Hayashi, A Robot Equipped with a High-Speed LSPR Gas Sensor Module for Collecting Spatial Odor Information from On-Ground Invisible Odor Sources, ACS Sensors, 10.1021/acssensors.8b00214, 3, 6, 1174-1181, 2018.06. |
| 16. |
Review of Microfluidic Devices for On-Chip Chemical Sensing
Microfluidic techniques can be a basis to realize user-friendly microanalytical devices of high performance. Required operations include injection of solutions to reaction chambers, volume measurement, and mixing of solutions. For this purpose, the use of surface tension is attractive. In hydrophobic flow channels, solutions can be moved stably in the form of plugs. Otherwise, solutions can be transported by capillary action in a hydrophilic flow channel and stopped at a hydrophobic valve. The valve can be opened autonomously by switching the mixed potential by wetting a zinc electrode formed in a controlling flow channel. In this review paper, we introduce some of our microfluidic devices particularly focusing on devices that work based on surface tension.. |
| 17. |
Sho Shinohara, You Chiyomaru, Fumihiro Sassa, Chuanjun Liu, Kenshi Hayashi, Molecularly imprinted filtering adsorbents for odor sensing, Sensors (Switzerland), 10.3390/s16111974, 16, 11, 1974-1974, 2016.11, Versatile odor sensors that can discriminate among huge numbers of environmental odorants are desired in many fields, including robotics, environmental monitoring, and food production. However, odor sensors comparable to an animal’s nose have not yet been developed. An animal’s olfactory system recognizes odor clusters with specific molecular properties and uses this combinatorial information in odor discrimination. This suggests that measurement and clustering of odor molecular properties (e.g., polarity, size) using an artificial sensor is a promising approach to odor sensing. Here, adsorbents composed of composite materials with molecular recognition properties were developed for odor sensing. The selectivity of the sensor depends on the adsorbent materials, so specific polymeric materials with particular solubility parameters were chosen to adsorb odorants with various properties. The adsorption properties of the adsorbents could be modified by mixing adsorbent materials. Moreover, a novel molecularly imprinted filtering adsorbent (MIFA), composed of an adsorbent substrate covered with a molecularly imprinted polymer (MIP) layer, was developed to improve the odor molecular recognition ability. The combination of the adsorbent and MIP layer provided a higher specificity toward target molecules. The MIFA thus provides a useful technique for the design and control of adsorbents with adsorption properties specific to particular odor molecules.. |
| 18. |
Kazuhiro Ikemoto, Takafumi Seki, Shohei Kimura, Yui Nakaoka, Shinnosuke Tsuchiya, Fumihiro Sassa, Masatoshi Yokokawa, Hiroaki Suzuki, Microfluidic Separation of Redox Reactions for Coulometry Based on Metallization at the Mixed Potential, Analytical Chemistry, 10.1021/acs.analchem.6b01234, 88, 19, 9427-9434, 2016.10. |
| 19. |
Electrochemical Bubble-Based Bidirectional Microfluidic Transport
With the aim of application to biochemical analyses, efficient bidirectional microfluidic transport was achieved through the reversible electrochemical production and shrinkage of hydrogen bubbles. A three-electrode system with a platinum black working electrode, a Ag/AgCl reference electrode, and a platinum auxiliary electrode was incorporated into a poly(dimethylsiloxane) structure containing the necessary flow channels and compartments. The influence of the electrode and flow channel structures on the operation of the system was investigated. The production and shrinkage of bubbles was achieved by applying appropriate potentials to the working electrode, which minimized the influence of spontaneous shrinkage resulting from the oxidizing effect of dissolved oxygen. Device performance depended on the structure of the working electrode, meaning that further optimization will be necessary. The device was shown to withdraw solution through a minimally invasive needle and to process liquid plugs in a microfluidic system.. |
| 20. |
Miniaturized shape memory alloy pumps for stepping microfluidic transport
A shape memory alloy (SMA) actuator and a polydimethylsiloxane (PDMS) elastic tube were used to realize a simple pump. A liquid plug in a flow channel could be moved forward and backward reversibly by exploiting the shape memory properties of the actuator. Two SMA sheets were used to create a peristaltic pump capable of moving a solution forward and backward over a long distance. The stepping transport caused by applying pulses of electric power facilitated the adjustment of the plug's position. Manipulations such as volume measurement and the merging of two plugs were demonstrated using a microfluidic device with a T-junction. © 2012 Elsevier B.V. All rights reserved.. |
| 21. |
Fumihiro Sassa, Hind Laghzali, Junji Fukuda, Hiroaki Suzuki, Coulometric Detection of Components in Liquid Plugs by Microfabricated Flow Channel and Electrode Structures, Analytical Chemistry, 10.1021/ac102289a, 82, 20, 8725-8732, 2010.10. |
| 22. |
Yuki Seto, Rina Inaba, Tomoaki Okuyama, Fumihiro Sassa, Hiroaki Suzuki, Junji Fukuda, Engineering of capillary-like structures in tissue constructs by electrochemical detachment of cells, Biomaterials, 10.1016/j.biomaterials.2009.11.104, 31, 8, 2209-2215, 2010.03. |
| 23. |
Shintaro Takahashi, Hironori Yamazoe, Fumihiro Sassa, Hiroaki Suzuki, Junji Fukuda, Preparation of coculture system with three extracellular matrices using capillary force lithography and layer-by-layer deposition, Journal of Bioscience and Bioengineering, 10.1016/j.jbiosc.2009.06.013, 108, 6, 544-550, 2009.12, Micropatterned cocultures were fabricated with 3 extracellular matrices, hyaluronic acid (HA), fibronectin, and collagen. The feature of the fabrication processes is to avoid the use of potentially cytotoxic materials and utilize capillary force of the solution and interactions between the extracellular matrix components. The coculture system can be used to investigate the effects of heterocellular interactions on cellular fate. Direct heterocellular connections between hepatocytes and fibroblasts were visualized by the transcellular diffusion of fluorescein in this coculture system. The interactions between hepatocytes and fibroblasts were crucial for the maintenance of albumin synthesis by hepatocytes. The coculture system was also beneficial for investigating the effects of cell-cell interactions on the induction of embryonic stem (ES) cell differentiation. In cocultures grown in a sea-island pattern, ES cells formed isolated colonies surrounded by PA6 cells and differentiated into neurons with branched neurites that extended from the colonies. This versatile and biocompatible coculture system could potentially be a powerful tool for investigating cell-cell interaction and for tissue engineering applications. © 2009 The Society for Biotechnology, Japan.. |
| 24. |
Biochip with integrated pumps for plug-based sequential exchange of solutions
A novel method for exchanging solutions used in biochemical analyses and a device to carry out the exchange are proposed. An array of plugs formed using six injectors was transported in a microflow channel using a main pump located at one end of the main flow channel. The injectors and main pump were operated on the basis of the change in volume caused by the electrolysis of water. Bubbles were produced from working electrodes; these bubbles caused a diaphragm placed below the injectors to inflate and occlude the inlet of the solution reservoir. Increase in the number of bubbles caused the reservoir to inject the solution into the main flow channel in the form of a plug. Each plug was individually transported downstream to the sensing area by the main pump, which was operated in a similar manner to the injector. The device was used for the detection of a tumor marker, α-fetoprotein (AFP). Plugs of necessary solutions were individually transported to the sensing area with immobilized primary antibodies to allow antigen-antibody binding, cleaning, and detection. The fluorescence intensity from the antibodies showed clear dependence on the concentration of AFP. The immobilization of antibodies could also be carried out on-chip. © 2009 Elsevier B.V. All rights reserved.. |
| 25. |
Fumihiro Sassa, Junji Fukuda, Hiroaki Suzuki, Microprocessing of liquid plugs for bio/chemical analyses, Analytical Chemistry, 10.1021/ac800492v, 80, 16, 6206-6213, 2008.08, A microfluidic device and operation to handle liquid plugs for biochemical analyses were developed for efficient handling of plugs of many solutions. A major part of the device was a T-junction consisting of a main flow channel and a handling flow channel. Unit operations including attachment of plugs, division of a plug, sorting of plugs, and formation of plugs of various lengths enabled controlled sequential reactions in a microflow channel. Rapid mixing could easily be achieved by moving a plug formed by merging two plugs back and forth. The device could be used for efficient characterization of performance in bio/chemical sensing. In experiments using L-glutamate oxidase, plugs containing an enzyme or a substrate were formed, mixed sequentially, and the intensity of fluorescence from plugs of different concentrations of L-glutamate or pHs could be measured simultaneously. Cross-contamination of plugs by neighboring plugs poses a problem in using the same flow channel repeatedly. However, the influence could be minimized by using a cleansing plug placed between them in a sufficiently hydrophobic flow channel and by processing the plugs at a low velocity. The device can be a critical component for microprocessing in various bio/chemical analyses. © 2008 American Chemical Society.. |
| 26. |
Fumihiro Sassa, Katsuya Morimoto, Wataru Satoh, Hiroaki Suzuki, Electrochemical techniques for microfluidic applications, Electrophoresis, 10.1002/elps.200700581, 29, 9, 1787-1800, 2008.05, Eletrochemical principles provide key techniques to promote the construction of bio/chemical microsystems of the next generation. There is a wealth of technology for the microfabrication of bio/chemical sensors. In addition, microfluidic transport in a network of flow channels, pH regulation, and automatic switching can be realized by electro-chemical principles. Since the basic components of the devices are electrode patterns, the integration of different components is easily achieved. With these techniques, bio/chemical assays that require the exchange of solutions can be conducted on a chip. Furthermore, autonomous microanalysis systems that can carry out necessary procedures are beginning to be realized. In this article, techniques developed in our group will be comprehensively introduced. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.. |
