Abstract: Objective To design and implement a low-power and portable transcranial direct current stimulator controlled by mobile phones. Methods The constant current stimulation circuit was realized by a field effect transistor, which could output stable and adjustable low-intensity direct current, and the impedance detection circuit and the over-current protection circuit increased the effectiveness and safety of the stimulator. The control and real-time detection of the stimulation circuit was realized through a microcontroller, and the parameters' settings of the stimulator and the display and preservation of the actual stimulus information were realized through the Android software on the smartphone. Results The output current strength and accuracy, maximum load, as well as the timing, device connection, stimulus information collection and display all achieved the expected goals. Conclusion The design realized the mobile control of the stimulator, with portability, low cost and low power consumption, providing a new solution for wider applications.

Key words: transcranial direct current stimulation, microcontroller unit, Android system, stimulus circuit