@@ -16,7 +16,11 @@ It is based on a discrete electrostatics solver (shown below), and also document
## Magnetic
Another proximity measurement uses the magnetic field instead of the electric field. Integrated circuits are available with extremely sensitive magnetostrictive, magnetorestive, and hall effect sensors. Using differential pairs of these elements, very low-cost, non-contact rotary and linear encoders can be made. A great resource for designing such magnetic devices is the <ahref='https://sensing.honeywell.com/hallbook.pdf'>Honeywell Hall Effect Handbook</a>.
Another position measurement uses the magnetic field instead of the electric field. Among magnetic field sensing technologies, hall effect sensors are the most ubiquitous. Integrated circuits with arrays of hall effect sensors are available at extremely low cost in very dense packages. Using differential pairs of these elements, non-contact rotary and linear encoders can be made. A great resource for designing such magnetic devices is the <ahref='https://sensing.honeywell.com/hallbook.pdf'>Honeywell Hall Effect Handbook</a>. Austrian Microsystems makes a variety of these devices for sensing position or rotation of a magnet.
For more sensitive, low field devices magnetoresistive sensing elements are often used. David Pappas of NIST compares noise floors of these technologies, noting hall effect sensors register around 300,000 ```pT/\sqrt{Hz}```, while magnetoresistive 200
Integrated circuits are available with extremely sensitive magnetoresistive and hall effect sensors.
