Background

Prior gecko electrostatics was based on the premise that dust nanoparticles (NPs) are ubiquitous and attach in large numbers to walls and ceilings. NP detachment by spatula located at the tip of toe-hairs was shown to produce electromagnetic (EM) radiation that by the photoelectric effect produced charge, thereby allowing the gecko to walk on room surfaces by electrostatic attraction. About 45 million <100 nm dust NPs were shown necessary to support the gecko weight. However, surface concentrations inferred from typical volumetric air concentrations suggest the necessary number of NPs may not be available to support the gecko on diverse room surfaces. Because of this, the limited number of dust NPs is shown compensated by the induced electrostatic attraction by as many as 6 billion spatulae.

Electrostatic Spatulae Mechanism

The EM confinement of the spatulae atoms differs from that of the dust NPs. Confinement of the spatulae as a thin annular disk centrally suported on the stalk is based on an extension of a principle first proposed by John Tyndall in the 1870’s. Tyndall’s principle of EM confinement relies on the properties of a dielectric (non-conducting) medium surrounded by another dielectric material of lower refractive index (RI). The spatulae is surrounded by air except at the spatulae interface with the stalk which is shown to act like a mirror to provide the EM confinement of the kT energy of spatulae atoms. See www.nanoqed.org at link “Gecko Update”

Thermal kT energy is recovered as the spatulae attach to room surfaces while detachment induces the emission of VUV radiation that charges the spatulae. Only contact is necessary to recover kT energy of spatulae atoms following VUV emission provided the surface is macroscopic that by quantum mechanics is allowed to have kT > 0. Thermal response is prompt because of the nanoscale thickness of the annular disk. Upon detachment, the EM confinement requires the kT energy to vanish with conservation proceeding by the spatulae emitting VUV radiation. By the photoelectric effect, the VUV induces the surface to lose electrons to charge positive with the electrons charging the spatulae negative. The gecko is therefore held to the room surface by the spatulae induced electrostatic force to significantly supplement that induced from dust NPs.

Conclusions

Gecko charging by detaching dust NPs with toe-hairs is limited by the availability of NPs on diverse wall and ceiling surfaes. However, the more than 600 million spatulae attached to the gecko toe-hairs that induce electrostatic attraction upon contact with the room surfaces more than compensate for the limited number of dust NPs to allow the gecko weight to easily be supported.

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