You must carefully choose insulation and apply guarding potentials, and you must use an amplifier with picoampere input-bias currents. 必须谨慎选择绝缘方法和使用保护电位,必须使用输入偏置电流为微微安级的放大器。
Study on Techniques for Current Measuring in the Picoampere Range pA级微电流测量技术研究