3 ms·

It uses Coulomb's law, a principle of attraction between electrical charges: http://senseg.com/technology/senseg-technology http://senseg.com/technology/senseg

by maeon3 15y ago

It uses Coulomb's law, a principle of attraction between electrical charges: http://senseg.com/technology/senseg-technology http://senseg.com/technology/senseg-technology Physics behind it: http://en.wikipedia.org/wiki/Coulomb%27s_law http://en.wikipedia.org/wiki/Coulomb%27s_law

deleted 15y ago
[deleted]
tocomment 15y ago
I still don't understand. How does running a current through an electrode produce an attractive force to a finger? The finger isn't going to have positively charged particles in it.
- icegreentea 15y ago
  A net neutral finger is still composed of negative and positive particles. Remember that the negatively charged particle (electrons) are relatively mobile. If you apply an external electrostatic gradient across a region, you end up with those electrons moving.
  - tocomment 15y ago
    So is this a repulsive or attractive force? Can you control that?
    - a-priori 15y ago
      Attractive only. If I remember my electrostatics, the rationale is that if the surface becomes positively charged, the positive charges in your finger will move away from the surface, leaving only the negative charges near the surface. Those particles will be attracted to the screen. If you reverse the charge so the surface is negatively charged, then the negative charges in your finger will be repulsed, leaving positive charges which will be attracted to the screen. Either way, your finger gets attracted to the screen.
      - tocomment 15y ago
        This is amazing. I've never heard of this before. I can think of millions of potential applications; make car tires stick to the road when cornering, replace seatbelts with a electric car seat, glasses that stick to your face, a phone that sticks to your ear, shoes without laces. I'm sure I could come up with a lot more ideas too.
      - icegreentea 15y ago
        For more detail (and to correct my previous post a bit), in materials with low electron mobility (aka insulators), what happens isn't so much the movement of charge carriers, but rather the orientation of each atom's electron field. Basically, by imposing a strong gradient, it will cause each individual atom's electron cloud to reorient/shift, which causes each atom to set up it's own little gradient which points in the opposite direction. You sum up those little reorientations amongst all particles in the material, and you end up with a net electric field that points in the opposite direction, which then becomes attractive. The above is a bit more accurate description of what happens in insulators (which accurately models some parts of our skin), while a-priori's description fits the conductor parts (most of the wet bits) of the human finger better. And obviously, this is just an approximation/model of what's going on.
        tocomment 15y ago
        So is this an effect I can create on my Arduino? How do I go about setting it up?

by maeon3 15y ago

deleted 15y ago

[deleted]

tocomment 15y ago

I still don't understand. How does running a current through an electrode produce an attractive force to a finger? The finger isn't going to have positively charged particles in it.

icegreentea 15y ago
A net neutral finger is still composed of negative and positive particles. Remember that the negatively charged particle (electrons) are relatively mobile. If you apply an external electrostatic gradient across a region, you end up with those electrons moving.
- tocomment 15y ago
  So is this a repulsive or attractive force? Can you control that?
  - a-priori 15y ago
    Attractive only. If I remember my electrostatics, the rationale is that if the surface becomes positively charged, the positive charges in your finger will move away from the surface, leaving only the negative charges near the surface. Those particles will be attracted to the screen. If you reverse the charge so the surface is negatively charged, then the negative charges in your finger will be repulsed, leaving positive charges which will be attracted to the screen. Either way, your finger gets attracted to the screen.
    - tocomment 15y ago
      This is amazing. I've never heard of this before. I can think of millions of potential applications; make car tires stick to the road when cornering, replace seatbelts with a electric car seat, glasses that stick to your face, a phone that sticks to your ear, shoes without laces. I'm sure I could come up with a lot more ideas too.
    - icegreentea 15y ago
      For more detail (and to correct my previous post a bit), in materials with low electron mobility (aka insulators), what happens isn't so much the movement of charge carriers, but rather the orientation of each atom's electron field. Basically, by imposing a strong gradient, it will cause each individual atom's electron cloud to reorient/shift, which causes each atom to set up it's own little gradient which points in the opposite direction. You sum up those little reorientations amongst all particles in the material, and you end up with a net electric field that points in the opposite direction, which then becomes attractive. The above is a bit more accurate description of what happens in insulators (which accurately models some parts of our skin), while a-priori's description fits the conductor parts (most of the wet bits) of the human finger better. And obviously, this is just an approximation/model of what's going on.
      - tocomment 15y ago
        So is this an effect I can create on my Arduino? How do I go about setting it up?