서울 대학교 동적 로봇 시스템 연구실 Tutorial of surface electromyography Part 1 : Making circuit and choosing muscle | 
 As I mention before surface electromygraphy ( sEMG ) is bio - electric signal which is come from human muscle unit . This time I ’ m going to introduce making a circuit to extract sEMG from human body and how to find muscle location for sensors . 
 1 . Muscle location 
 Actually , It is very hard to find muscle location to general persons . Most of people don ’ t know much about muscle structure and mechnism . So I suggest this site which constructed by google ( yeah it is free ! ) http : / / www . zygotebody . com / 
 this site shows anatomy of human body . you can estimate location of muscle by using this for example if you want to know muscle which is connected to knee , you can click and see just like this picture . 
 you can find the name of muscle and it ’ s attached bone . after that you should attach sensors to your body . Usually bone area is ground . 
 the picture shows how to attach sensors to bicep muscle . 
 2 . Circuit for EMG signals extraction 
 Circuit of EMG signal extraction is very simple . There are three step for circuit . 
 Instrument amplifier is for amplify the EMG voltages . I usually use AD 620 for this but you can use INA series else . The gain is modified from data sheet of your device . 
 I made three EMG circuit and this is for forearm muscle ’ s EMG signals . You can change cutting frequency as you wish . It is quite diffrent cutting frequency for purpose 
 Next time I ’ m going to go introduce ADC of EMG signals usually used method for preprocessing .