Hand-Sensing Dryer

Introduction

Public restrooms are havens for bacterial infections. Users generally touch flush valves for toilets and urinals, door pulls and locks, handles for hot and cold water faucets, soap dispensers, trash containers, and sometimes diaper-changing stations. Washing your hands before leaving the restroom is the most effective way to prevent the spread of infectious diseases, but the method of drying your hands often results in recontamination. Scientific research has proven that warm air hand dryers are more hygienic for drying hands than paper towel drying; however, a dryer with hands-free operation improves sanitation even more by eliminating contaminated push buttons. Touchless hand dryers have the added benefit of reducing maintenance and utility costs. As a STEM extension to the “Graphing Your Motion” experiment, you will create your own automatic hand dryer using a Vernier Digital Control Unit (DCU) to turn on a small DC fan when the Motion Detector senses the presence of your hands.

Objectives

• Turn on a fan when the Motion Detector senses the presence of your hands.
• Control a sensor-based system with the DCU.

Reference Experiment

• “Graphing Your Motion” – Experiment 33 from Middle School Science with Vernier
• “Graphing Your Motion” – Experiment 35 from Physical Science with Vernier
• “Graph Matching” – Experiment 1 from Physics with Vernier