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Do there exist materials that:
- React to electrical pulses having frequency in the band 2-10Hz with a very low frequency response (near to DC), - Have a measurable reaction, where measurable means that I can directly transduce the signal into an electrical one by connecting in some way the material to an electronic circuit,
- The reaction is easy to measure, easy means that the measurement circuit is very elementary,
- Dissipates very low power (microWatts (or orders about 10^2 microWatt ) if possible).

I actually don't care about the way these materials react, they can also emit some light whose spectrum varies with the pulses frequency.

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  • \$\begingroup\$ Liquid crystals can do this, but they are not very easy to use. \$\endgroup\$ – venny Sep 20 '14 at 12:40
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    \$\begingroup\$ Your "do not dissipate power ... do not allow any current to flow through them" requirement makes this difficult. To have a reaction, work is going to get done at some physical level, and that requires power to be used in some way. Otherwise you are asking for something with 'perpetual motion machine' properties (which is impossible). If you loosened that restriction, and indicated what level of power use you'd be willing to accept, then there may be answers. What are you trying to achieve? Is this a lab experiment, or a machine your trying to build? \$\endgroup\$ – gbulmer Sep 20 '14 at 12:50
  • \$\begingroup\$ There are many, of which the first which springs to mind is an inductor. What are you trying to do? \$\endgroup\$ – EM Fields Sep 20 '14 at 12:50
  • \$\begingroup\$ The OP says "do not dissipate power ... do not allow any current to flow through them" \$\endgroup\$ – gbulmer Sep 20 '14 at 12:51
  • \$\begingroup\$ Indeed; an inductor exposed to an externally applied electromagnetic pulse will have a voltage induced across its winding, but if it's not connected to anything no current will flow in it. \$\endgroup\$ – EM Fields Sep 20 '14 at 12:59
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One example would be a chamber containing pure nitrobenzene with electrodes on either side. Applying an electric field causes a rotation of the polarization of light passing through the chamber. Here's a reference to the original paper.

Since nitrobenzene is a dielectric, little current flows, and only a tiny amount of power is dissipated in the Kerr cell when the switching happens (due to losses in the dielectric). However the driving circuitry may well dissipate a fair bit of power if the switching occurs at a highly frequency.

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  • \$\begingroup\$ Thanks, but an alternating electric field will cause an alternating polarization? (and therefore another oscillatory measurable phenomena?) Because if it is I obtain an oscillatory signal from an oscillatory signal and this is useless. Unless there's a very simple way to detect whether the light is changing its polarity, in this case I can recognize that there are oscillations in the original electri signal and the goal is reached \$\endgroup\$ – LJSilver Sep 20 '14 at 15:24
  • \$\begingroup\$ Yes, response is DC to high frequency. It's easy to detect by interposing polarizing filters which results in amplitude modulation of the transmitted light. There are crystals such as KTP which are more practical than liquids. \$\endgroup\$ – Spehro Pefhany Sep 20 '14 at 15:33
  • \$\begingroup\$ and what about signals at low frequency (1 to 5 Hz) ? \$\endgroup\$ – LJSilver Sep 20 '14 at 19:57
  • \$\begingroup\$ Yes, 1-5Hz is between DC and HF, so KTP etc will respond. \$\endgroup\$ – Spehro Pefhany Sep 20 '14 at 20:02

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