Hand Sanitizer Dispenser

Objective: Design a hands-free hand sanitizer dispenser that works with both squeeze bottles and small pump bottles. Problem: The pump arm couldn't fully push down the pump head and would lock up; the nozzle wasn't far enough out of the box to dispense onto the user's hand. Solution: Use a stronger motor and redesign the wall to fit the dimensions needed to dispense outside the box correctly. Built for my mechanical design class final project, during COVID-19 — many tools and measurement devices weren't at our disposal. A force meter would have helped me design around the required pump-bottle forces; without one I had to make assumptions and design around incorrect forces. The dispenser uses a LEGO NXT Mindstorm control box, ultrasonic sensor, and a motor turning one revolution every 2 seconds an object is detected. A squeeze arm pushes 8mm into the bottle when a hand is sensed, dispensing the right amount. The push-bottle version locked up because the spring was too stiff for the linkage / motor design — replacing with a softer spring helped but still didn't allow full motor rotation.