Improved assemblies, systems, and methods provide an MES processor for acquisition and processing of myoelectric signals from muscles, nerves, or central nervous system tissue, or any combination. The MES processor is sized and configured to be implanted subcutaneous a tissue region. The MES processor includes an electrically conductive case of a laser welded titanium material. Control circuitry is located within the case, the control circuitry including a rechargeable power source, a receive coil for receiving an RF magnetic field to recharge the power source, and a microcontroller for control of the MES processor. Improved assemblies, systems, and methods also provide an acquisition and processing system for sensing myoelectric signals from muscles, nerves, or central nervous system tissue, or any combination. The acquisition and processing system provides at least one electrically conductive surface, a lead connected to the electrically conductive surface, and an MES processor electrically connected to the lead.