The aim of this work was to measure the lifetime of neural implant test samples at two different temperatures, using a method that allows the precise measurement of the sample lifetime, further analysis with the use of Weibull statistics, and examination of the applicability of the Van’t Hoff rule. The correct estimation of the lifetime of neural implants is important to avoid preliminary failures, when used in humans. The novelty lies in the precise data due to the measurement approach, the application of the Weibull statistics to neural test samples, and the examination of the Van’t Hoff rule’s applicability to the longevity of polyimide-based neural implant samples. Several samples that consisted of interdigitated gold strands, encapsulated in polyimide were soaked in ringer solution. One batch was soaked at a temperature of 37 °C, and another was soaked at a temperature of 57 °C. Voltage was applied and measured to identify the occurrence of failures. The long-term experiment was stopped after 458 days for the samples at 37 °C and 423 days for the samples at 57 °C, with several samples still being intact at both temperature levels. The time to failure was measured and used to identify the Weibull parameters that would describe the behavior of the samples. The median lifetime of the samples changed from 363 days at 37 °C to 138 days at 57 °C. The scale and shape factor changed from 396 and 3.7 at 37 °C to 138 and 2 at 57 °C, respectively. The measured mean, median times, and Weibull scale factors were lower than expected from the Van’t Hoff rule. The use of the Van’t hoff rule with 2ΔT/10°C for accelerated lifetime tests would lead to an estimation of longer lifetimes than realistic. A reaction rate constant around 1.47 appears more appropriate. While a fourfold difference in lifetime would be expected, only a 2.65-fold difference in the median lifetime and a roughly 2.2-fold difference in the mean and Weibull scale factor were observed. The shift of the Weibull shape parameter from 3.7 at 37 °C to 2 at 57 °C with rising temperatures was observed, indicating differences in failure reasons and stronger aging at lower temperatures. The used method is simple to apply and interpret and allows for a precise anticipation of sample lifetimes.

中文翻译：

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使用体外测试结构分析神经植入物的寿命

这项工作的目的是测量神经植入测试样品在两种不同温度下的寿命，使用一种可以精确测量样品寿命的方法，使用威布尔统计进行进一步分析，并检查 Van 的适用性不是霍夫规则。正确估计神经植入物的寿命对于避免在人体使用时出现初步故障非常重要。新颖之处在于测量方法带来的精确数据、威布尔统计在神经测试样本中的应用，以及范特霍夫规则对基于聚酰亚胺的神经植入样本寿命的适用性的检查。将由封装在聚酰亚胺中的叉指金线组成的几个样品浸泡在林格溶液中。一批在37℃的温度下浸泡，另一批在57℃的温度下浸泡。施加并测量电压以识别故障的发生。37℃样品458天和57℃样品423天后长期实验停止，有几个样品在两个温度水平下仍然完好无损。测量失效时间并用于确定描述样品行为的威布尔参数。样品的中位寿命从 37°C 时的 363 天变为 57°C 时的 138 天。比例因子和形状因子分别从 37 °C 时的 396 和 3.7 变为 57 °C 时的 138 和 2。测量的平均值、中位时间和威布尔比例因子低于范特霍夫规则的预期。使用范特霍夫规则和 2ΔT/10°C 进行加速寿命测试将导致估计的寿命比实际寿命更长。1.47 左右的反应速率常数似乎更合适。虽然预期寿命会有四倍的差异，但观察到中位寿命仅存在 2.65 倍的差异，平均寿命和威布尔比例因子仅存在约 2.2 倍的差异。随着温度的升高，观察到威布尔形状参数从 37 °C 时的 3.7 变为 57 °C 时的 2，这表明失效原因存在差异，并且在较低温度下老化程度更强。所使用的方法易于应用和解释，并且可以精确预测样品寿命。