Related Experiment Videos
Stimulus induced pH changes in cochlear implants: an in vitro and in vivo study
C Q Huang1, P M Carter, R K Shepherd
1CRC for Cochlear Implant & Hearing Aid Innovation, Lane Cove, NSW, Australia.
Annals of Biomedical Engineering
|October 16, 2001
Summary
High-intensity electrical stimulation can alter tissue pH, potentially harming neural prostheses. This study found that clinical stimulation levels cause minimal pH changes, but higher intensities do, influenced by rate, intensity, and direct current levels.
Area of Science:
- Biomedical Engineering
- Neuroscience
- Electrophysiology
Background:
- Tissue pH changes can negatively impact neural prostheses.
- Understanding pH shifts during electrical stimulation is crucial for safe device design.
Purpose of the Study:
- To investigate stimulus-induced pH changes in neural prostheses.
- To determine safe stimulation parameters for neural implants.
Main Methods:
- Electrical stimulation (biphasic pulses) applied to platinum electrodes in vitro and in vivo.
- Varying stimulus intensity (0.025-0.68 µC/phase) and rate (62.5-14,500 pps).
- pH monitoring using indicators and microelectrodes in various solutions and biological tissues.
Main Results:
- Clinical stimulation levels showed no significant pH shift.
- Intensities above clinical levels induced pH changes, correlated with stimulus rate, intensity, and direct current (dc).
- Capacitive coupling and alternating leading phase pulse trains minimized pH shifts.
Conclusions:
- Stimulation parameters significantly influence pH changes in neural prostheses.
- Safe stimulation strategies require careful consideration of intensity, rate, and dc levels.
- Buffered solutions and in vivo conditions reduce pH shifts compared to unbuffered saline.