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AD8232 for EMG Signal Conditioning

Question asked by Yamahonda450 on Sep 17, 2012
Latest reply on Mar 25, 2013 by Eliton



I'm a ME student but I'm interested in EE and I have some circuits knowledge so please feel free to take the time to educate or correct me throughout the discussion.  My grandma recently suffered a stroke and I wasn't happy with the passive rehabilitation she was getting so I set out to design a more active solution.  I designed a myoelectric controlled orthosis.  It’s a motorized arm brace that assists through the range of motion and it senses and uses the muscle contractions as the trigger.  I designed the EMG amp/filter/rectifier circuit with components from texas instruments and it works fine but it requires a +/- supply which is currently two 9 volt batteries in series with ground between them.  The microcontroller (arduino nano) requires a 7-12V supply and the motor requires 12V.  Everything is done and everything works except the integration of the power supply for these three components is too confusing and TI isn’t much help.  Everything needs to be compact and fit into the orthosis so I want a single battery solution. 

In doing research on power supply circuits I came across the AD8232 and it seemed like an easy way to solve the power issue since it was designed to be powered directly from a 3v coin battery or I can use the arduino nano’s built in 3.3v LDO which can source up to 50mA.  I also decided to go with two 6v servo motors instead of one 12v.  That said, the power supply issues have been resolved… but only if the AD8232 will work for EMG signal conditioning.  EMG signals are around 1.5mV and from 10Hz-1000Hz with most of the signal power around 150Hz.  It seems like it would work just fine but I want to make sure.  If it will work, I have a list of specific questions pulled from the data sheet that I’d like to discuss.


Thank you,

Chad K