# Failure mode analysis of silicon-based intracortical microelectrode arrays in non-human primates

###### tags: `論文摘要` `穩定性` `電極介紹`

- Link: https://doi.org/10.1088/1741-2560/10/6/066014
- MLA: Barrese, James C., et al. "Failure mode analysis of silicon-based intracortical microelectrode arrays in non-human primates." Journal of neural engineering 10.6 (2013): 066014.
- 年分: 2013
- 期刊: Journal of neural engineering

## 整理造成micro electrode array (MEA)失效的原因

1. 生物
發炎、免疫反應
2. 材料性
針腳斷裂、絕緣材料破損等
不一定會導致訊號消失，但會導致訊號震幅下降
3. 機械
受到外力導致位移，或針腳被拉出


## 判斷電擊失效的依據

1. waveform的SNR
2. waveform的Peak to Peak voltage

## 統計


## 詳細判斷作法

For each channel on each array on each day, all spike waveforms were aggregated to compute SNR and PTP amplitude for that channel. Signals were first filtered with a single-pole analogue anti-aliasing filter with a 7.5 kHz cut-off frequency. The signal was then filtered using a fourth order Butterworth digital high-pass filter to extract spiking waveforms. This signal was sampled at 30 kHz. A neural spike was determined by this signal crossing a threshold typically set at −4.5 dB of the distribution of signal values, but this was not always the case (sometimes set manually). A spike waveform spans 1.6 ms or 48 samples. Ten of these samples were before the threshold crossing and 38 samples were after the threshold crossing. Any channel that had >150 threshold crossings over a recording session was considered active and was further analyzed. SNR was calculated in two parts. The noise amplitude for a channel was determined by finding the maximum and minimum values of each of the first five samples of the 48-sample window for all threshold crossings (typically tens of thousands). Recall that the first five samples precede the threshold crossing and should be uncontaminated by the actual spike waveform, although occasional pretrigger inflections in the waveform may be included and could increase noise estimate. The noise amplitude is the max–min difference of the mean over five points for all threshold crossings. We calculated the signal amplitude (PTP) by taking the median (across threshold crossings) of all samples and then finding the difference between the maximum and minimum of the median waveforms. The median was chosen in order to prevent large amplitude noise signals from artificially inflating the PTP. The ratio of the signal amplitude to the noise
amplitude was the SNR.