Variable spacing four-point probe pin device and method

A continuous variable spacing probe pin device, comprising:

• a first probe pin including a first outer surface;
• a second probe pin including a second outer surface;
• and,
• an actuator, wherein:
• the first and second probe pins are configured to measure a property of a conductive layer;
• the actuator is arranged to roll the first and second outer surfaces along the conductive layer, while maintaining contact of the first and second probe pins with the conductive layer, between first and second configurations of the device;
• in the first configuration of the device, respective first portions of the first and second outer surfaces in contact with the conductive layer are separated by a first distance;
• in the second configuration of the device, respective second portions of the first and second outer surfaces in contact with the conductive layer are separated by a second distance different from the first distance;
• and
• each respective first portion has a first area that differs in size from a second area of each respective second portion.

A method of measuring a property of a conductive layer using a continuous variable spacing probe pin device including a first probe pin and a second probe pin, the first and second probe pins configured to measure the property, the method comprising:

• contacting the conductive layer with the first and second probe pins such that first respective equal areas of the first and second probes are in contact with the conductive layer;
• and,
• rolling the first and second probe pins along the conductive layer such that second respective equal areas of the first and second probes are in contact with the conductive layer, wherein:
• the first respective equal areas are different in size from the second respective equal areas.