Sample Design Input and Output for a Neuromuscular Stimulator

Originally Published MDDI April 2003

Design Control

Design Input:

Requirements (each of the following items could reference a source, such as market analysis of competing products, consulting clinicians, or patient focus groups)
• Patients require electrical activation of various limb muscles without stimulation of cutaneous nerves.
• Patients need a portable system that is easily worn on the body and that will operate continuously for at least 4 hours without recharging.
• Muscle activation needs to span range from threshold to maximal contraction with at least 10 approximately logarithmically spaced levels.
• Clinicians desire graphical selection of stimulus parameters based on intensity relative to threshold without need to consider individual stimulus parameters. Constraints (each of the following items could be a separate, brief review of the most relevant literature)
• Patterns of neuromuscular architecture and innervation
• Influence of implantation technique on electrode design
• Contributions of stimulus pulse current and duration to effective intensity
• Effects of motor unit firing rates on contractile force
• Effects of electrode geometry and impedance on power dissipation and battery life

Design Output:
Specifications 
Electrode 
• Configuration
• Materials
• Contact size
• Impedance
Stimulus pulse 
• Waveform
• Current
(min, max, step size)
• Duration
(min, max, step size)
• Repetition Rate
(min, max, step size)
Implementation
Electrode
• Bill of materials
• Component drawings and
suppliers
• Assembly procedures
• Testing procedures
• Jigs and fixtures
Stimulator
• (Similar to above)

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