Force-Sensitive Resistors

One property of the sea ice that I’m interested in measuring is its hardness. Similarly to the way materials like diamond and steel are given a “hardness rating,” I would like to try to quantify the hardness of ice. In particular, I want to look at how the hardness of ice changes as the absorbance of light on the surface changes. To measure ice’s hardness, I will be using a force-sensitive resistor to measure changes in voltage as applied force varies. In addition to measuring the force, I will also use a square-pyramid shaped tip to create an indentation in the ice. By comparing the area of the indentation with the force required to create it, I will be able to quantify the hardness of ice using the Vicker’s hardness test. This week I have been working on creating a calibration curve that I will use as a standard to equate voltage readings with force. To do this, I measured the voltage increase that resulted from placing a variety of masses on the sensor. When I am in Alaska, I will use the force from a clamp to create the indentation, and the voltage at that force will be recorded. By comparing the voltage reading to my calibration curve, I will be able to approximate the amount of force it took to create the indentation.

As I said before, I want to compare these force readings to the absorbance (or reflectivity) of the surface ice. I want to measure the albedo, or the percentage of light that is reflected by a surface, for the ice. I originally guessed that light with higher reflectivity would have higher structural integrity and thus a higher hardness level. To measure properties of ice related to light, we will be using a variety of light sensors that will quantify light interactions across the majority of the EM spectrum. We have sensors that will measure IR, UV, and visible light. More information of the specifics of the light sensors will come later. For now, here is a picture of a small circuit that includes two of the light sensors that we will use.