Vacuum Insulated Membrane

Image from Steve Bowers
A typical VIM including over-lapping diamondoid scales filled with vacuum, and extra insulation layers separating the diamond scales

A vacuum insulated membrane[1] is a form of thermal insulation technology. A typical membrane is around five micrometers thick and is composed of at least two layers of overlapping, hollow, thin-walled diamondoid[2] scales. The interior of the scales is a near perfect[3] vacuum, and the inside surfaces of the vacuum cavities are mirrored, typically with aluminum, which is 95% reflective of thermal infrared.

Layering membranes allows the creation of materials with an extraordinarily high insulative property. Each membrane has, minimally, four reflective layers, and each layer reflects 95% of incident thermal radiation. If an uninsulated mass losses 1,000 joules per second via radiative transfer, then if it was insulated by a single membrane it would lose only 0.00625 joules/s. Three membranes would result in a loss of only 2.44140625 x 10-13 joules per second, or 385.22 joules every 5 x 107 years. This extreme performance makes VIMs the preferred thermal insulation technology in most applications, in which the membrane materials can withstand the heat flux and mechanical stresses without failing.

A few of the numerous common applications are:
  • VIMs that are equipped with microscale heat pumps can form a diaphanous thermal regulation suit that can allow endothermic bionts to maintain homeostasis within environmental conditions that range from cryogenic to several hundred degrees Kelvin.
  • Aerostatic steam balloons that are small enough to loft synsects and similar-sized bots.
  • Beverage and food containers that maintain their contents hot or cold.
  • Long term thermal energy and cryogenic material storage.
  • Camouflage against thermal infrared imaging. In the case of camouflaged entities that generate waste heat, the camouflage ability is time-limited to onboard reserves of cryogenic mass to dump the heat into.

[1]Also known as a Hall-membrane, after the Information Age theorist J. Storrs Hall, who originated the idea.
[2] Diamond is an excellent conductor of heat, so insulative buffer layers separate diamond from diamond.
[3] In the femto- to attopascal regime.

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Development Notes
Text by John Edds
Initially published on 17 December 2015.