Summary

COVID-19 can remain contagious on surfaces like door handles, and redesigning public facility doors is necessary to limit transmission. One solution is a door with an automatic UV light device that disinfects the handle. A motion sensor detects door movement and turns on a 222 nanometer UV light for 20 seconds, killing 99.9% of SARS-CoV-2. The design uses internal, replaceable batteries and meets health standards.

Overview: The Product

1.1 The Problem

Coronavirus disease (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) became a global pandemic in early 2019 and still is an ongoing problem now for most countries, including the United States. The airborne virus is transmitted human-to-human via "droplets, contaminated hands, or surfaces of various materials (Chen et al., 2020)." Thus, people in crowded places are especially prone to the disease. FDA research has shown that "a person can get COVID-19 by touching a surface or object that has the virus on it and then touching their mouth, nose, or possibly their eyes". Additionally, it is proven that the virus on surfaces like stainless steel and plastic can stay contagious for 2 – 3 days ("COVID-19 Frequently Asked Questions", 2022). In indoor places with high foot traffic, the door handle is one of the most common victims of bacteria and viruses since people must push or pull the door to enter or exit the building. Research has also shown that "fourteen different colonies of bacteria were living on the knob" of a public building, and these germs could spread throughout the entire facility within hours ("Why You Should Avoid Door Handle Germs", 2022). With that said, how might we redesign the doors of public facilities to limit COVID-19 transmission by disinfecting door handles?

1.2. The Solution

In order to solve the problem stated above, I propose a redesign of the door with an automatic ultraviolet (UV) light device that disinfected the handle after the door is used. Ultraviolet (UV) rays are naturally present in sunlight. Studies show that "UV light can be used to kill airborne COVID-19 particles and disinfect surfaces." Therefore, it is widely used in health facilities. On the other hand, overexposure to UV light could cause adverse health effects such as skin cancer, corneal damage, and decreased vision ("Additional COVID-19 Questions", 2022). Therefore, the application of this redesign must be carefully considered, which this paper will explain in the following sections. The design comprises a motion sensor that detects whether a person is opening and closing the door. A UV light device at the wavelength of 222 nanometers is mounted at the center on top of the door handle. After the motion sensor detects door movements, the UV light is automatically turned on for 20 seconds. This is proven to be the most efficient UV light wavelength that kills 99.9% of SARS-CoV-2. The 222 nanometers wavelength also meets the health standard required by ACGIH (Ma et al., 2021). Details of the research and standard will be discussed in 2.2.2 and 2.2.3. Internal, replaceable batteries power the sensor and UV light device. The proposed design differs from traditional door handles as it’s capable of detecting door movement and automatic disinfection is performed.

Design Process
2.1. User-group and CLIMBER Analysis

The design of this product utilizes the CLIMBER Analysis. Customer and Life. First, the targeted user group wants to avoid COVID-19 infection and contact the virus as little as possible. They might be prone to infection as they work at crowded places like restaurants, supermarkets, and health facilities. Door handles are especially likely to spread disease in these places. The user’s lifestyle might be busy, or they are essential workers with long working hours and heavy social duties. Insight and Mechanism. An effective design would limit virus transmission by frequently disinfecting door handles. It should be automatic and only sanitize if movement is detected. It should not be noticeable by the user or require users' action. It should not degrade user experience with liquid sanitation, leaving the handle wet and sticky. With that said, I developed the idea of a door-mounted UV light device that disinfects the door handles. This redesign is marketed to places with high foot traffic. The maintenance is easy, and it does not require changes in existing user behavior.

2.2. Research and Supporting Ideas

Patent 1: Self-Powered Sanitizing Door Handle (Patent Number: US20100140499A1) Pub. Date: Jun. 10, 9 2010 Inventor: Joseph N. Casale, Cary, NC (US) This product is a door handle that incorporates a UV light source (figure 1.) It explains how the movement of the door handle can rotate the gear train and activate the generator, which produces the electrical energy that powers the UV light source. The UV light is "directed to an outer surface of the actuator, thereby deactivating microorganisms on the outer surface (Casale, 2010)." However, in my proposed design, this mechanism could not work for door handles of different types. For example, most doors in public facilities have metal plates or bars that cannot be rotated. Changing the style would result in changes in users' behaviors and routines. On the other hand, I could utilize the electro engineering perspective to use a sensor and power the UV light source (figure 2.)

Proposed Human Factors Requirements

1. The UV light should only be activated when no user passes through the door.

2. The activation time of the UV light should be limited to 20 seconds.

3. The UV light disinfection device should only be installed at places with no or few additional sources of UV light.

4. Ensure the total UV light exposure does not exceed the exposure limit of one hour and 20 minutes.

5. Inform users who could potentially contact the device about the risk of UV light with supporting scientific evidence.

6. The self-sanitizing device above the door handle does not interfere with the efficiency of the door operation.

7. The door with the self-sanitizing device does not require additional tasks performed by users.