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 µWatt 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.

We have measured the interaction between superfluid 3 He-B and a micromachined goalpost-shaped device at temperatures below 0.2 T c . The measured damping follows well the theory developed for vibrating wires, in which the Andreev reflection of quasiparticles in the flow field around the moving structure leads to a nonlinear frictional force. At low velocities the damping force is proportional to velocity while it tends to saturate for larger excitations. Above a velocity of 2.6 mms −1 the damping abruptly increases, which is interpreted in terms of Cooper-pair breaking. Interestingly, this critical velocity is significantly lower than reported with other mechanical probes immersed in superfluid 3 He. Furthermore, we report on a nonlinear resonance shape for large motion amplitudes that we interpret as an inertial effect due to quasiparticle friction, but other mechanisms could possibly be invoked as well.