This PDF file contains the front matter associated with SPIE Proceedings Volume 11477, including the Title Page, Copyright information, and Table of Contents.

Flexible electronics and soft robotics have been drawing much attention. However, prevention of fracture of materials and devices in three-dimensional deformation remains a challenge. Design of strain in the materials and devices enables durable high-performance materials and devices. In this study, surface strain analysis of bending polymer films by a novel method called a surface labeled grating method is introduced.

In chiral-liquid-crystal (LC*) phased, LC molecules are aligned helically; hence, the refractive indices of the LC* materials are altered periodically along the helical axis. The LC* materials have unique optical properties, such as selective reflection, that arise from the periodic structure of the refractive index. The wavelength of the selective reflection depends on the helical pitch as it is a Bragg reflection; therefore, we can control the reflective wavelength by controlling the helical pitch. In this study, we observed the mechano-optical behaviors of LC* elastomers, and discussed the relationship between the chemical structures of elastomers and mechano-responsive optical properties. When tensile strain was applied to the films, reversible hypsochromic shift in the reflection wavelength was induced. The results of the mechano-optical behavior observed for the LC* elastomers suggest that LC* materials have potential for application in mechanical sensors for soft robots.

Photoactive materials hold great promise for a variety of applications. We present a finite element model of light-controlled flexible magnetic composite structure composed of 33.3% Chromium dioxide (CrO₂) and 66.7% Polydimethylsiloxane (PDMS) by weight. The structure has a dimension of 8 mm × 2 mm × 100 μm and has been previously experimentally studied. Due to the low Curie temperature, the structure acts as an actuator, shows significant deflection under the external magnetic field and relaxation due to laser heating. Thermal and magnetic deflection analysis has been performed using the FEM model. The simulation results show a maximum structural deflection of 6.08 mm (76% of the length of the structure) when subjected to 30 mT magnetic flux density and 160 mW laser power at 303 K (room temperature). We will present the results of the simulation model and comparison to experimental data reproducing the previously observed motion of the (CrO₂+PDMS). This model will enable future fracture and fatigue analysis as well as extension to new photoactive geometries.

We study two photon absorption (TPA) induced surface relief formation in an azo-polymer thin film by illumination of picosecond near-infrared optical vortex pulses with the corresponding intensity of >5 GW/cm2 at the focal plane. We discover, for the first time, that the optical vortex creates an unexpected flower-shaped surface relief with 3-8 petals along an azimuthal direction, corresponding to the topological charge of the incident optical vortex. This surface relief manifests the modulational instability associated with nonlinear light-matter interaction in the azo-polymer film.

Synthetic molecules mimicking the structure and function of proteins gain increasing importance for development of molecular devices and medicines. Membrane proteins are important targets due to their unique functions such as ion transportation and stimuli responsiveness, and give good models for development of synthetic molecular machines. We have been involved in development of amphiphilic multiblock molecules, consisting of linearly connected hydrophilic oligo(ethylene glycol) units and hydrophobic aromatic units, as simple structural mimics of transmembrane proteins. We found that the hydrophobic units of these molecules tend to form face-to-face stacking in a lipid bilayer membrane, to give folded structures as transmembrane proteins, thereby allowing transport of ions across the membrane. This molecular design has an advantage in that the molecules could easily gain stimuli- responsiveness by introducing functional units at the hydrophobic units.

In 1995, we succeeded in observing a single molecule in an aqueous solution (Nature). In addition, we incorporated the technology of observing with precision of one nanometer and one ms, and measured the movement of molecular motor, myosin working in muscles in detail. We found that the myosin molecular motor moves by utilizing thermal fluctuation (Brownian motion). Computer simulation showed that the motion of myosin molecular motors utilizing thermal fluctuation successfully explains the flexible and adaptive mechanical properties of the muscle that they assemble.

Advances in molecular design and synthetic chemistry enable the development of novel molecular therapeutic treatments of diverse diseases. A strategy proposed nearly 25 years ago for the treatment of metastatic cancer, but never realized, entails the following general processes: (i) Accumulation of an insoluble scaffold in the tumor extracellular space upon native enzyme (E_nat) cleavage of a soluble precursor, and (ii) covalent attachment to the scaffold of a non-native (heterologous) enzyme (E_het), which catalytically converts an abundance of aqueous-soluble radionuclide-bearing prodrug to an aqueous-insoluble drug; the latter precipitates in the tumor extracellular space. Here, the design and chemical synthesis of a molecular entity (1) for formation of the scaffold are described. Compound 1 is an “A₂BC”-type lysine-based architecture that contains two chromogenic indoxyl-glucoside units (A), which upon cleavage by a glucosidase (E_nat) undergo oxidative dimerization to provide a water-insoluble indigoid polymer; a maleimide (B) for attachment to a cancer-targeting agent; and the binding motif Loracarbef (C), a carbacephem antibiotic that forms a covalent adduct with a mutant β-lactamase (a proposed tether to, and/or possible fusion protein with, E_het). Studies here also include maleimide–thiol conjugation of I to transferrin (a cell uptake carrier) and the covalent attachment of a mutant b-lactamase to Loracarbef. Together, the work supports an approach for molecular brachytherapy (or endoradiotherapy), where radionuclide seeds are self-assembled directly in the region of therapeutic need.

More than ever, rapid and precise methods for detection of bacterial and viral pathogens are requested by our crowded society. In this study, we have detected label-free NASBA RNA amplicons of human pathogens using two sensing systems: binary (split) peroxidase-like deoxyribozyme (Dz) and a cascade of RNA-cleaving and peroxidase-like Dz. We accomplished detection of Escherichia coli and Streptococcus pneumoniae, as well as the DNA virus from Herpes group, HSV1. The sensitivity of the system was as low as 10 bacterial or 10 virus infected cells. The method requires regular boiling-water bath, 1.5 h of total time and 30 min hands-on time for split technology and around 3 h total time with 1 h 30 min hands-on time for cascade sensor with obvious benefits and binary sensor usability. The total cost of reagents and disposables is no more than 1 $ per test. This study demonstrates that both methods can be used for selective and costefficient detection of human pathogens with naked eye. The study lays a foundation for point-of-care diagnostics of infectious diseases with instrument-free visual output signal.

We shall describe our work on the development of an optical control method based on the destabilization of biological membranes. As a destabilization agent, we explore the use of an azobenzene molecule that has both hydrophobic and hydrophilic ends. Our working hypothesis is based on the photo induced microscopic volume changes that can be obtained as a result of photo isomerization of azobenzene molecules inside the membrane. The current results, challenges and possible avenues will be presented and discussed.

We have demonstrated a linear nanomotor employing lateral optical force exerted on a plasmonic nanoparticle, in which the force direction is determined by the orientation of the nanoparticle rather than a field gradient or propagation direction of the incident light beam. The arrangements of the nanoparticles provide the lateral force distributions with nanoscale precision and resolution, resulting in not only linear but also rotational movement of a micrometer-sized object. Our nanomotors would provide a paradigm shift in optical manipulation as it removes the need for oblique incidence, focusing and steering of the light beam.

In the present study, we propose a combined (hybrid) approach of optical manipulation and photochemical reactions for achieving nano-photomechanical motions with small particles. Aa photochemical reactions, we have employed P-type and T-type photochromic reactions of diarylethene (DAE) and pyranoquinazoline (PQ) derivatives, respectively. Single polymer particle containing each of the photochromic compounds was optically trapped in water with a CW visible laser. At this stage, the particle experienced mainly gradient force and was trapped at the focal point of the CW laser. The absorption force was negligible because most of the photochromic molecules in the particle were in the colorless form. UV exposure induced the photoisomerization of the photochromic molecules, resulting in the increase in the number of colored forms. As a result, the absorption force acting on the particle increased and, the position of the particle shifted towards the light propagation direction depending on experimental condition. After turning the UV light off, the particle went back to the original position. The trapped particle thus underwent reciprocal motion synchronizing with the change of photo-response due to the photochromic reactions.

An optical vortex, possessing an orbital angular momentum, induces helical mass transfer of the irradiated materials, manifesting the helical trajectory of the optical vortex. Here, we propose an entirely novel patterning technology, termed optical vortex laser induced forward transfer (OV-LIFT), based on optical vortex induced helical mass transfer. Going beyond the conventional laser induced forward transfer, this technique allows the formation of a micrometer-scale spinning jet, so-called ’spin-jet’, made of a variety of ultrahigh viscosity donor materials, with extremely long flight distance.

Two-color light was irradiated to azo-polymer films to investigate the mechanism of light-induced polymer movement. A collimated green light was used for inducing softening of the polymer, while a focused red light was used for inducing optical gradient force. We found from the topology change of the film that polymer movement was induced only when both green and red light were simultaneously irradiated. This finding indicated that the polymer movement was induced by optical gradient force generated by the red light under the condition that the polymer was softened by repeatable photoisomerization by the green light.

We designed, developed and tested a series of benzalkylsilane molecules in self-assembled monolayers (SAMs) to investigate their degree of order and electrical properties when anchored to silicon substrates. The molecules consist of a silane anchoring group and a nitrogen-substituted benzene ring, separated by a propyl group and imine linkage. By varying fabrication procedures and the ring substituents, we obtained a vast range of rectification ratios, between 10-3100. The highest value was obtained for the molecule (E)-1-(4-cyanophenyl)-N-(3-(triethoxysilyl) propyl)methanimine. We assign the efficient rectification behavior to a highly ordered SAM and coupling between the delocalized lone pair of electrons from the nitrogen termination and the device electrode. These devices were employed for sensing applications allowing for sensitive detection of humidity. Overall, the utilization of these molecular devices will allow for functionable, cost efficient, and easily integrable devices.

In order to realize a simple and small sized tunable laser with biomaterial based thin films, azo molecule Disperse Red 1 (DR1) was incorporated into DNA-surfactant complex with several fashions. Large photoinduced response with was observed under cw green laser excitation. With introducing a laser dye into blend films composed of DR1-copolymer and DNA complex by immersing them into dye solutions, we succeeded in the demonstration of laser oscillation with low pumping energy and quick tuning with a simple mechanical operation. For improvement of the film quality, a new surfactant including azocarbazole dye was synthesized, showing comparable laser induced birefringence.