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The chemical mechanism for formation of electronically excited-state molecules from the thermal reaction of dimethyldioxetanone was studied. Light production in the presence of certain easily oxidized aromatic hydrocarbons was found not to conform to the classical mechanistic schemes for chemiexcitation. Detailed investigation of the dioxetanone s stem revealed light formation by the recently discovered, chemically initiated electron-exchange process. This result is extrapolated to bioluminescent systems. In particular, the key high-energy molecule involved in firefly luminescence, which has been identified as a dioxetanone, is postulated to form excited states as a result of intramolecular electron transfer from the phenoxythiazole moiety to the dioxetanone. Subsequent rapid decarboxylation results in direct formation of an excited singlet state of the emitting amide. Bioluminescent organisms are widely distributed throughout terrestrial and aquatic environments. Although the biological purpose of luminescence varies from species to species, the chemical mechanism for generation of the electronically excited state, which subsequently emits light, appears to be general in a wide variety of organisms. In nearly all of the bioluminescent processes that have been investigated, high-energy cyclic peroxide molecules are implicated as providing the energy necessary for excited state generation (1). In the study of bioluminescent mechanisms the central concerns have been: (i) identification of the molecule capable of undergoing a reaction with a free energy change sufficient to permit excited state generation, (ii) characterization of the emitting species, and (iii) identification of the molecular process that converts the high-energy reactant to an electronically excited product molecule.Our recent investigations (2) of chemiluminescence have led to the discovery of a general mechanism of excited state formation identified as chemically initiated electron exchange luminescence. Studies of exergonic chemical reactions that model bioluminescent systems now permit us to suggest that this mechanism is operative in the formation of electronically excited states in living organisms. The light-forming reaction of the North American firefly (Photinus pyralis) will serve as the prototypical case. The conclusions reached from this system are readily extended to other bioluminescent reactions.Many excellent studies of bioluminescence from the firefly have led to the characterization of the enzyme/substrate system involved in the light generation step (3). In summary, the substrate luciferin has been identified as 1 and independently synthesized. Reaction of 1 with oxygen in the presence of the enzyme luciferase generates a high-energy content molecule that has been identified as the dioxetanone (2) by 180 labeling studies (4, 5). In order to produce bioluminescence, 2 loses the The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "adv...

Among ElectroActive Polymers(EAPs) the dielectric elastomer actuator is regarded as one of the most practically applicable in the near future. So far, its effect on the actuation phenomena has not been discussed sufficiently, although its strong dependency on prestrain is a significant drawback as an actuator. Recent observations clarifies that prestrain has the following pros and cons: prestrain plays an important role in generating large strain, whereas it rather contributes to the reduction of the strain. Prestrain provides the advantages of improving the response speed, increase of the breakdown voltage, and removing the boundary constraint caused by the inactive actuation area of the actuator. On the contrary, the elastic forces by prestrain makes the deformation smaller and the induced stress relaxation is severely detrimental as an actuator. Also, the permittivity decreases as prestrain goes up, which adds an adverse effect because the strain is proportional to the permittivity. In the present work, a comprehensive study on the effects of prestrain is performed. The key parameters affecting the overall performances are extracted and it is experimentally validated how they work on the actuation performance.

A kind of dielectric elastomer (DE) material, called 'synthetic elastomer', has been developed based on acrylonitrile butadiene rubber (NBR) to be used as a dielectric elastomer actuator (DEA). By stacking single layers of synthetic elastomer, a linear actuator, called a multistacked actuator, is produced, and used by mechatronic and robotic systems to generate linear motion. In this paper, we demonstrate the application of the multistacked dielectric elastomer actuator in a biomimetic legged robot. A miniature robot driven by a biomimetic actuation system with four 2-DOF (two-degree-of-freedom) legged mechanisms is realized. Based on the experimental results, we evaluate the performance of the proposed robot and validate the feasibility of the multistacked actuator in a locomotion system as a replacement for conventional actuators.