UCSD_MED Stethoscope Disinfection

Stethoscope Cover Dispenser

 Spring 2019 MAE 156B Project

Sponsor: Dr. Heather Hofflich

hhofflich@ucsd.edu

Final Design

Promotional Video

Background and Motivation

Today, more and more doctors are trained to wash their hands in between patient visits. However, few doctors disinfect their stethoscopes in between patients. Indeed, stethoscopes have many bacteria on the     diaphragm, the piece in contact with sick patients. Our sponsor, Dr Hofflich helped us to conduct a survey amongst physicians at her clinic. In the targeted clinic with a sample size of 36 doctors, about 60% of the doctors wiped their stethoscopes with Isopropyl-Alcohol (IPA) as show in the survey result below.  Therefore, we are motivated to design and build a device that can disinfect the stethoscope diaphragm or that can prevent bacteria growth on the stethoscope diaphragm.

Survey Result

Objectives

The primary objective of this project is to design and build a device that can disinfect the stethoscope diaphragm or that can prevent bacterial growth on the stethoscope diaphragm. The device should be easy to operate and accessible in an examination room. It should also be quick to operate. We have proposed many possible designs including a spraying device, a UV disinfection device and a auto-wiping device. In the end, we have decided to use the barrier method and to design and build a stethoscope cover dispensing device that dispenses stethoscope cover quickly. Ideally, the device should be fully mechanical with a handle to be turned by doctors. It should take one turn at the handle to dispense one stethoscope cover.

Sterilization Methods

Design

As the figure shown below, our device consists of a handle, gears, a bullnose, a spool, a ratchet and pawl mechanism and hubs. A tape of stethoscope covers go through the hubs, the bullnose and the top spool. When the handle is turned, it will drive the gears and spool so that stickers are dispensed at the bullnose. The dispensed covers are than held on a receiving platform, which is attached to the body of the device. The gear ratios and spool radius are specified such that it takes one turn at the handle to dispense one sticker. The tape of stickers are also shown below.

Final Prototype

Stethoscope covers

Performance

As the video below shows, it takes around one turn at the handle to dispense one stethoscope cover. The device is relative small so that it can be placed on doctor's desk easily. To save space, it can also be placed on walls. In our previous design, the initial separation of cover stickers from the base tape was successful but at the end of the separation process the cover bounced back and re-stuck to the base tape, which is undesired. Therefore, a second iteration of design was performed to design and build the final prototype as shown on this webpage. In this final prototype, the device is more compact and the resticking problem is solved by tightening the screws on the bullnose to make it and its metal bottom plate squeeze the covers harder.

Prototype Performance