“…Then, more sturdily constructed biofuel cell prototype was partially (anode compartment only) implanted in rabbit ear (Miyake et al, 2011), which was reflected in the maximum cell current (1.50 μA), whereas the power of this cell reached 0.42 μW at 0.56 V and in brain of a living rat with a maximum power of 2 μW cm −2 at a cell voltage of 0.4 V (Andoralov et al, 2013). Later, with the recent improvements in terms of carbon nanotube (CNT) compression and direct electron transfer, researchers were successful to increase the power (38.7 μW) obtained from the implanted biofuel cell in a rat, using a specially designed electronic circuit to charge a capacitor, to run a LED, or a digital thermometer (Zebda et al, 2013). Recently, researchers reported a glucose/oxygen biofuel cell using FAD-dependent glucose dehydrogenase enzyme at the anode side operating in human serum, which produces maximum power densities of 39.5 ± 1.3 and 57.5 ± 5.4 μW cm −2 for EFCs at 21 and 37°C, respectively (Milton et al, 2015).…”