Graphene Conductivity: Testing the Resistance

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Discussion Overview

The discussion revolves around the conductivity of a graphene sample tested by a participant, specifically focusing on the unexpected observation of negative resistance. The scope includes experimental observations and theoretical implications related to graphene's electrical properties.

Discussion Character

  • Experimental/applied
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant reports testing a graphene sample on polyethylene and observing negative resistance, questioning whether this could be explained by a capacitive effect.
  • Another participant suggests that the negative resistance reading may be due to discharging static charge from the polyethylene.
  • A subsequent reply proposes grounding the sample to eliminate potential faulty readings before measuring again.
  • Further contributions discuss the phenomenon of negative differential resistance in graphene, noting its potential applications in high-speed transistors and the lack of significant electrostatic charge detected with a sensitive electric field meter.

Areas of Agreement / Disagreement

Participants express differing views on the cause of the negative resistance readings, with some attributing it to static discharge while others reference inherent properties of graphene. The discussion remains unresolved regarding the exact explanation for the observed phenomenon.

Contextual Notes

There are limitations in the measurements and assumptions about the experimental setup, including the influence of grounding and the nature of the materials used. The discussion does not resolve the mathematical or theoretical implications of negative resistance in graphene.

Who May Find This Useful

This discussion may be of interest to those studying materials science, electrical engineering, or anyone exploring the properties and applications of graphene in electronics.

Matthew Travers
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Hi
I've made what I think is graphene. I first put the solution on cardboard and then I put some on polyethylene.
When they had dried, I tested conductivity with a digital multimeter with the scale set on megaohms.
The cardboard was nonconducting, but the sample on poly to my astonishment showed a negative resistance.
I touched the 2 probes together and they read zero, touched them back to the poly sample and again got anegative resistance. Since I am confident that thermodynamic laws are fully universal on all scales governing all energy interactions from solar concentrators to theoretical maxwell demons involving measuring quantum states, there has to be a conservative explanation. Is it some sort of capacitive effect?
 
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Negative resistance? You're discharging static charge on the polyethylene.
 
Thanks for that. So if I connected the sample to Earth first, that would eliminate the faulty reading?
 
Sample and meter leads (and probably your hands) to the same ground should take care of it.
 
Hang on, just caught up to you...earth everything to discharge and then measure after disconnecting earth.
Will try that and a couple of other ideas like putting foil on the other side of the polyethylene and connecting that to the sample so it acts like a shorted cap. Cheers mate
 
What I found was perhaps not electrostatic discharge. Apparently graphene demonstrates negative resistance or negative differential resistance where an increase of current through the material counter intuitively leads to a drop in voltage. Researchers intographene transistors are seeking to exploit the effect as they predict switching speeds over 400Ghz. It certainly explains why I was unable to detect any significqnt electrstatic charge with the hypersensitive e-field meter I have( its not a DMM). Going to look into this effect more and see if I can come up with anymore uses for it.
I'll keep you posted. Many thanks for the feedback
 

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