Biological channels produce the signals of the nervous system, and coordinate the contraction of muscle, including the heart, by responding to voltage. Biological channels are proteins with a specific piece of machinery that responds to voltage, called the voltage sensor. The voltage sensor moves charges through an electric field creating a polarization (i.e., dielectric) current that can be measured in the far field some $10^{23}$ atoms away from the channel because Maxwell's equations enforce the perfect conservation of current, as Maxwell defined it. Maxwell's current includes the polarization of the vacuum, independent of the properties of matter (including proteins!) no matter how complex. We have built a precise electromechanical model of the voltage sensor based on its atomic scale structure that fits a wide range of experimental data.