Figure 2.

Cala ONE device and study design. a. Electrode placement on subject's wrist to target median and radial nerves, with counter‐electrode positioned on posterior surface of the wrist. b. Subject tremor frequency is captured during a 20 seconds postural hold (middle 10 seconds recorded by the device). The peak tremor frequency is determined on‐board the device and is input into the stimulation waveform to deliver a subject‐specific stimulation. c. Waveform consists of a series of charge balanced biphasic pulses delivered at a frequency of 150 Hz, 300 μs pulse width, and 50 μs interpulse period alternating between the median and radial nerve at a frequency equal to the tremor frequency. d. TETRAS and ADL scores were collected before and after treatment or sham stimulation sessions, and CGI was collected after the session. Both groups underwent the same frequency calibration and stimulation amplitude setting. Treatment consisted of a ramp up of stimulation (typically 1‐2 minutes) followed by a 40‐minute stimulation, whereas sham included a ramp up of 1 minute followed by a rapid ramp down of the stimulation. [Color figure can be viewed at wileyonlinelibrary.com]