  We report the design, elaboration and measurements of an innovative planar
thermoelectric (TE) devices made of a large array of small mechanically
suspended nanogenerators (nanoTEG). The miniaturized TE generators based on SiN
membranes are arranged in series and/or in parallel depending on the expected
final resistance adapted to the one of the load. The microstructuration allows,
at the same time, a high thermal insulation of the membrane from the silicon
frame and high thermal coupling to its environment (surrounding air,
radiations). We show a ratio of 60% between the measured effective temperature
of the membrane, (and hence of the TE junctions), and the available temperature
of the heat source (air). The thermal gradient generated across the TE junction
reaches a value as high as 60 kelvin per mm. Energy harvesting with this planar
TE module is demonstrated through the collected voltage on the TE junctions
when a temperature gradient is applied, showing a harvested power on the order
of 0.3 $\mu$Watt for a 1 cm 2 chip for an effective temperature gradient of 10
K. The optimization of nanoTEGs performances will increase the power harvested
significantly and permit to send a signal by a regular communication protocol
and feed basic functions like temperature measurement or airflow sensing.
