Biological surface electromyographic switch and necklace-type button switch control as an augmentative and alternative communication input device: a feasibility study.

Augmentative and alternative communication (AAC) is an approach used to supplement, improve, and support the communication of those with speech or language impairments. We developed an AAC device for diverse approaches, using an electromyographic (EMG) switch and a necklace-type button switch. The EMG switch comprised an EMG signal processor and a switch interface processor. EMG signals were processed using an electrode through the stages of signal acquisition, amplification, filtering, rectification, and smoothing. In the switch interface processor, the microprocessor determined the switch as ON or OFF in response to an input EMG signal and then converted the EMG signal into a keyboard signal, which was transmitted to a smart device via Bluetooth communication. A similar transmission process was used for the necklace-type button switch, and switch signals were input and processed with general-purpose input/output. The first and second feasibility tests for the EMG switch and button switch were conducted in a total of three test sessions. The result of the feasibility test indicated that the major inconvenience and desired improvement associated with the EMG switch were the intricacy of the AAC device settings. The major inconveniences and desired improvements for the necklace-type button switch involved device shifting, volume and weight, and inconvenience in fixing the switch in various directions. Thus, based on the first and second feasibility tests, we developed an additional device. Finally, the EMG switch and necklace-type button switch developed to remedy the inconveniencies had high feasibility.