Question 1
a. In detail, elucidate how your device is representative of/different from the physiological environment. Indicate how these variables may affect neural functionality.
In order to record neuronal signals, my device, specifically the electrode, will be inserted into the rat sciatic nerve to record extracellularly the action potential generated by the neurons. There are several differences between the electrodes and the medium into which they will be inserted. Depending on these differences, there may be an effect on the neural functionality. The first difference to consider is the Young’s modulus of the nerve and the electrode. The electrode, which is made from polysilicon, has a Young’s modulus of around 155 GPa1 while the nerve itself has a Young’s modulus of around 580 kPa2. A large mismatch in Young’s modulus can lead to the electrode being encapsulated by non-neuronal cells as the body attempts to minimize the damage caused by having something stiff inserted into soft tissue. The difference in Young’s modulus interferes with the
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Current research is making progress on addressing several issues but there is no ideal device. In the following, I will describe what I believe an ideal device would be.
One of the first issues that needs to be addressed is the mismatch between the Young’s modulus of the electrode and the tissue into which it is inserted. An electrode needs to be stiff enough to puncture into the tissue and be able to move within the tissue without simply bending and not going deeper. As such, the issue of the mismatch can be addressed by coating the electrode in a soft conducting polymer that has a Young’s modulus as close to the tissue as possible. This way, the electrode remains stiff enough to easily move through the tissue while having a soft barrier to minimize the damage of the