Liquid Crystal Sensor

This is a classroom activity to explain liquid crystal sensors for middle school students. A list of activity materials and .pdf handouts are included. The objectives of the activity are to "understand how liquid crystals (LCs) relate to other phases of matter (liquid, solid, gas); observe that liquid crystals reflect many different colors (wavelengths) of light; learn that thermally sensitive LCs twist and turn (change pitch & orientation) at different temperatures, which changes the particular color of light that they reflect; learn that just like some LCs can measure temperature, others can 'sense' particular chemicals and biological agents; explore how LC sensors can be used to detect changes that cannot be seen with the naked eye; and brainstorm particular applications of LC sensors."