Materials List: Lab Experiment:
Build Simple Coulter Counters to Count Particles

For Part 1, each group needs:

  • plastic bottle with 1.5 mm hole drilled into cap
  • 2 plastic cable ties
  • ring stand with clamp holder and ~10 cm rod
  • scissors
  • Simple Coulter Counter Lab Handout, one per person

For Part 2, each group needs:

  • 1 kΩ resistor
  • 9V battery
  • insulated wire
  • 9V battery snap connector

For Part 3, each group needs:

  • computer with data-acquisition and Microsoft Excel® software applications
  • data-acquisition equipment (see note below; also see Troubleshooting Tips section)
  • voltage probes

For Part 4, each group needs:

  • 600 ml beaker
  • stirrer

For Part 5, each group needs:

  • a second 600 ml beaker

For Part 6, each group needs:

  • Vial of "paint sample" with 1 mm diameter particles to be counted. (Make sample as described in Procedure section, by putting ~0.5 ml of grinding media plastic particles in a vial and filling with salt water solution [the same solution used elsewhere in the lab].) One source for plastic particles is Grinding Media Depot® at; the grinding media come in a range of sizes; we suggest ~1mm-sized particles of PMMA, which has the density closest to water. Note: When we ordered the grinding media, a minimum order of $50 was required, which was far more than you would use for multiple years worth of classes.

For Part 1, to share with the entire class:

  • hole punch

For Part 2, to share with the entire class:

  • electrical tape
  • wire strippers

For Part 4, to share with the entire class:

  • liquid soap (enough for 2-3 drops per group)
  • NaCl salt (enough for 0.3 g per group)
  • scale (to measure salt in grams)
  • water

For Part 5, to share with the entire class:

  • printer

For teacher:

  • drill and bit (to create 1.5 mm holes in plastic bottle caps)

A note on data acquisition equipment: The sample data provided for this lab was obtained using the following two different pieces of equipment.

  • The Vernier LabQuest® Mini ($149) comes with the LoggerPro Lite® software and has a maximum sampling rate around 1000 samples/second when taking data for 30 seconds. A separate voltage probe ($12) must also be purchased for this lab.
  • The DATAQ® DI-148U ($50) has a sampling rate of 240 samples/second when using the software provided and does not require a separate probe.