For getting the higher resolution signals the scientists implement electrodes directly into the gray matter of the human brain. Also we can set it on the surface of the brain beneath the skull. This technique helps to get direct reception of electric signals and also allows placing electrode in a specific area in the brain. But this technique has many problems. This requires surgery and it also a cause for the formation of scar tissue. The scar tissue does not allow the flow of signals or it blocks the signals. Neurons voltage difference is measured by the electrodes. After that the signal is amplified. The next step is filtering of the amplified signal. Cochlear implant is the most common and the oldest way for using BCI. In average person the sound waves will enter through the ear and it passes through many small organs. It passes the vibrations into the auditory nerves as an electric signal. If the person loosed his hearing ability then he can’t hear anything.
Different types of electrodes are used for brain computing. The main types are needle electrodes, disposable (gel-less and pre-gelled types), headbands and electrode caps, reusable disc electrodes (gold, silver, stainless steel or tin), saline-based electrodes. The amplifier used for it should not influenced by the physiological process. Measured signal do not distorted. The amplifier must have good interferences and separation of signals. And also it must protect the patient from any type electric shock. It can resist against the high input voltages.