1.4 Current status of technologies for autonomous microsystems 9 Table 1.1 Examples of mass, size, and power consumption of the cell, averaged within different taxonomic groups Cell average within different taxonomic groups Prokaryote Cyanobacteria Eukariotic microalgae Protozoa Human cells (Source: [12]) Wet mass, kg 2 Â 10 ­15 7 Â 10 ­14 6 Â 10 ­12 3 Â 10 ­11 10 ­12 Volume, m m 3 2 70 6000 3 Â 10 4 1000 Size, m m 1.3 4 18 32 ~10 Power, W 10 ­14 2.5 Â 10 ­13 5 Â 10 ­11 2.5 Â 10 ­10 4 Â 10 ­12 subject to spontaneous degradation. Therefore living organisms must spend some energy to fight accu- mulating disorder, for example to repair damage by replacing some `broken' macromolecules, etc. [17]. A characteristic measure of the rate of energy consumption, or power, by living organisms is their metabolic heat rate. Studies across a broad spectrum of the organisms have revealed a striking