3D-printed electronic electrostatic machines

By 2015, I started some experiments with electrostatic generators made with 3D-printing techniques, with the objective of developing generators that could be used for energy harvesting applications. The generators were based on variable capacitors, with their structures printed with conductive ABS filament. These generators operate at very high impedance level, and so are insensitive to the resistivity of the material.

The first experiment was with a device comprising two pairs of complementary variable capacitors, that could be interconnected in several ways along with four high-voltage diodes and extra capacitors to create different generators [1], [2]. It was moved by a small motor in a back-and-forth movement. It worked very well, but with a low maximum speed, of about 10 Hz.

Pair of complementary variable capacitors with back-and-forth movement.

The second experimental device used a pair of multiple comb capacitors, with a movable part suspended from springs and driven at the mechanical resonance, 18 Hz, by a solenoid acting on a magnet. The structure was designed to be compatible with construction as microelectromechanical systems (MEMS). A complex demonstration system was built around the device, extracting energy using a low-power DC/DC converter and using the energy to power a digital wireless link, exchanging data with a remote transceiver [3], [4]. The system also worked well, and could generate enough energy for the demonstration.

Complementary multiple comb machine with resonant movement, DC/DC converter and load devices.

In the experiments related in the references, the devices were limited to operate at 300 V at the input of the DC/DC converter, when it was used. The small distances between the capacitor plates (~1 mm) limited the maximum voltage over the variable capacitors to about 1 kV.

Video of the resonant generators. Demonstration, at the ISCAS 2017.

References

[1] A. C. M. de Queiroz and L. C. M. de Oliveira Filho, Energy harvesting with 3D-printed electrostatic generators, LASCAS 2016, Florianópolis, Brazil, pp. 127-130, February 2016.
[2] A. C. M. de Queiroz and N. Telles de Menezes, Energy harvesting with pairs of variable capacitors without control systems, Analog Integrated Circuits and Signal Processing, June 2018. Direct link.
[3] A. C. M. de Queiroz and L. C. M. de Oliveira Filho, Live demonstration: Unipolar symmetrical variable-capacitance generators for energy harvesting, ISCAS 2017, Baltimore, USA, p. 1739, May 2017.
[4] A. C. M. de Queiroz and L. C. M. de Oliveira Filho, Unipolar symmetrical variable-capacitance generators for energy harvesting, 60th MWSCAS, Boston, USA, August 2017.