Panescu D, Webster J G, Stratbucker R A
E P Technologies, Incorporated, Sunnyvale, CA 94086.
IEEE Trans Biomed Eng. 1994 Jul;41(7):672-80. doi: 10.1109/10.301734.
This work presents a model for the skin which accounts for both the nonlinearities and the asymmetries in its voltage-current characteristic. This model consists of an electrical submodel and a heat transfer submodel. The electrical submodel uses nonlinear devices in which some parameters depend on skin temperature. The heat transfer submodel models the heat exchange between the skin, the surrounding tissues, and the ambient medium and calculates the temperature of the skin to update the necessary parameters of the electrical submodel. The model is based on experiments designed to determine: 1) the dry skin voltage-current characteristic; 2) the changes in the skin breakdown voltage with location; 3) the moist skin voltage-current characteristic; 4) the changes in the voltage-current characteristic of the skin with duration after the onset of stimulation; and 5) the effect of skin temperature on its voltage-current characteristic. During these experiments we used 84-mm2 square Ag-AgCl electrodes to apply sinusoidal voltage of 0.2 and 20 Hz. The simulations were performed using the Advanced Continuous Simulation Language (ACSL), capable of solving differential and integral equations with variable coefficients. The model predicted the skin behavior satisfactorily for a large range of amplitudes and frequencies. We found that the breakdown occurred when the energy delivered to the skin exceeded a threshold. Above this threshold the voltage-current characteristic of the skin became nonlinear and asymmetric and, in a real situation, the subject would experience an uncomfortable sensation which could rapidly develop into pain.
这项工作提出了一种皮肤模型，该模型考虑了其电压 - 电流特性中的非线性和不对称性。该模型由一个电气子模型和一个热传递子模型组成。电气子模型使用了一些参数取决于皮肤温度的非线性器件。热传递子模型对皮肤、周围组织和周围介质之间的热交换进行建模，并计算皮肤温度以更新电气子模型的必要参数。该模型基于旨在确定以下内容的实验：1）干性皮肤的电压 - 电流特性；2）皮肤击穿电压随位置的变化；3）湿性皮肤的电压 - 电流特性；4）刺激开始后皮肤电压 - 电流特性随持续时间的变化；以及5）皮肤温度对其电压 - 电流特性的影响。在这些实验中，我们使用84平方毫米的方形银 - 氯化银电极施加0.2赫兹和20赫兹的正弦电压。模拟使用高级连续模拟语言（ACSL）进行，该语言能够求解具有可变系数的微分和积分方程。该模型在很大的幅度和频率范围内令人满意地预测了皮肤行为。我们发现，当传递到皮肤的能量超过阈值时就会发生击穿。高于此阈值，皮肤的电压 - 电流特性变得非线性且不对称，并且在实际情况下，受试者会感到不舒服，这种感觉可能会迅速发展为疼痛。
