Cranial Electrotherapy Stimulation (CES) is Transcranial Alternating Current Stimulation (tACS)
Don’t mistakenly think that tACS is something altogether different than CES.
All CES devices deliver transcranial alternating current stimulation - none employ direct current. To become a CES device, a tACS device needs to demonstrate (to the FDA) “substantial equivalence” to previous CES devices and market the intention to treat depression, anxiety and insomnia.
CES is a regulated class of tACS devices.
CES devices as a class are not defined by a single electrode montage, set of frequencies or amperage output - these may differ from device to device. But CES devices never employ direct current, known as tDCS, or integrate other forms of neurostimulation with tACS.
The definition of “substantial equivalence” allows for a limited range of electrode placement, frequency and output possibilities for CES - at the Agency's discretion. The Fisher Wallace Stimulator uses electrodes above the temples and delivers 1-4 mA of alternating current using three frequencies. Other CES devices use ear-clip electrodes, deliver less than 2 mA of output, and use different, lower frequencies.
Based on the difference in website traffic as measured by Alexa, its likely that more Fisher Wallace devices were sold in the US in 2017 than all other CES devices combined. As a result, the Fisher Wallace electrode, frequency and amperage settings help define CES as a regulated class of tACS devices.