Folhas Artificiais

Artificial leaves, made from semiconductors, might one day help to remove excess airborne carbon dioxide and maybe even turn it into fuel. Real leaves, the green ones deployed by plants, perform many valuable tasks, not the least being the removal of CO₂ from air and its replacement with breathable O₂. Artificial CO₂ fixation needs several ingredients: light, a catalyst (such as CdS), and organic molecules.

A new study by a Oak Ridge-Vanderbilt team of physicists suggests how this process can be made more efficient, a necessary step if artificial fixation is ever to practical on a large scale. Contrary to previous ideas, the study shows, fixation does not take place directly on the catalyst surface. Rather it's a two step process: ionization of the CO₂ occurs at the surface, creating a highly reactive radical which can later combine with other CO₂ molecules or organic molecules in the vicinity.

Stephen Pennycook (pennycooksj@ornl.gov, 865-574-5504) says that his study looks at the role of catalyst surface roughness (flat planes of CdSe don't work as photocatalysts, but nanocrystals of the same material do) and at the possibility that nanocrystal doping might obviate the need for light, which would allow some fixation to take place in dark smokestacks. (Wang et al., Physical Review Letters, upcoming.)

(ler original aqui)

Moscas Como Combustível

Wikipedia

EcoBot is short for Ecological Robot and it refers to a class of energetically autonomous robots that can remain self-sustainable by collecting their energy from (mostly) waste in the environment. The only by-product from this process is carbon dioxide, which would have been produced from biodegradation in the first place. This carbon dioxide production belongs to the immediate carbon cycle of our planet and does not impose to the already increasing problem of the greenhouse effect.

So far autonomy in robotics has been directly linked with the ability of agents to compute and execute tasks, i.e. follow a set of rules given in an algorithm, with minimum human intervention. This is classified as computational autonomy, however it does not necessarily take into account the problem of energy collection and management. Energetic autonomy, therefore, refers to the ability of artificial agents to remain self-sustainable, with minimum human intervention.

EcoBot-I

EcoBot-I, developed in 2002, by the same group of workers at BRL, UK, utilised sugar as the fuel and ferricyanide in the cathode, to perform phototaxis (i.e. move towards the light) [Ieropoulos et al. 2003a, b; 2004].

The two EcoBots do not employ any other form of conventional power supply and do not require any form of initial charging from an external source. Instead, they are powered directly by the onboard microbial fuel cells (MFCs). This is in contrast with Gastrobot, which although it was the first example of a practical application that employed MFCs, it used onboard conventional batteries and required initial charging from the mains.

EcoBot-II

EcoBot-II, developed in 2004, by Melhuish, Greenman, Ieropoulos and Horsfield at the Bristol Robotics Laboratory (BRL) UK, was the first robot in the world to perform sensing, information processing, communication and actuation phototaxis, by utilising unrefined biomass. In fact, it consumed dead flies, rotten fruits and crustacean shells as the fuel and oxygen from free air as the cathode. EcoBot-II operated continuously for 12 days after having been fed with 8 houseflies of the species Musca domestica [Ieropoulos et al. 2005a, b; Melhuish et al. 2006].

EcoBot-II is the first practical example of a Symbot (symbiotic robot) that exhibited artificial symbiosis – the beneficial integration between the live microbial part and the artificial mechatronic part.

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