Two electrodes that measure changes in the body's surface moisture are attached to the palms of your hands.
测量体表湿度变化的两个电极被连接到你的双掌上。
《柯林斯英汉双解大词典》
2
It's a bit like if you're pushing a boat through a river and measuring something about the surface - you don't want to measure the ripples from the boat.
The US space agency on Friday launched a satellite to observe levels of salt on the surface of the world's oceans and measure how changes in salinity may be linked to future climate.