As it goes, the mechanical design (which I assumed would be a small percentage of my design effort) has become the foremost bottleneck in my quest to automate the spraying of sanitizer. Fortunately, I believe I am on the right track and will hopefully have a fully functional prototype in the coming week. The issue is primarily with the piston, which was originally designed with the thought that at low pressure there would be no overflow or leakage from the cylinder. I have since calculated a cylinder pressure of approximately 387 Pa and while the pressure is quite low, the imperfect surface of the 3D printed parts leads to leakage. My solution is to make a small groove, sized for a common O-ring, in the tip of the piston. The O-ring will act as a seal to eliminate the need for a perfectly smooth cylinder, the only downside I can see so far is the need for a stronger spring. The quest for automated spraying continues!
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In light of the continuing COVID-19 pandemic and based on current research regarding fomite transmission of viruses such as SARS-CoV-2, I am developing a device to combat door-handle to hand viral transmission. The device is designed to mount to a door approximately 5 inches above any common door handle. Using ultrasonic transducers and a specially programmed micro-controller, the device should be able to detect when the handle has been used. After detection, a stepper motor actuates a cam to drive a piston into a low pressure atomizer nozzle (currently being developed) which expels a fine mist of sanitizer onto the door handle.
The current design:
As I make progress, I will make updates to this blog to keep a consolidated record of the project history.
In the wake of the COVID-19 Pandemic, vital medical supplies are more difficult to obtain for healthcare workers. Respirators, like the CDC recommended N95 [1], are in short supply. Therefore, many communities have enlisted the aid of seamstresses and other makers to supply hospitals with alternative masks. At this time it seems appropriate to recruit all available resources to meet these critical supply shortages. As such, many 3D printing hobbyists are developing printable respirators that use common materials for filtering. The OS (Open Source) Respirator is a unique prototype respirator, that utilizes swap-able filters, with a theoretically longer (or easier maintained) lifespan than cloth masks.
Disclaimer: Like cloth masks, the OS Respirator is not intended to replace the CDC recommended N95 respirators [1]; however, the OS Respirator is designed to provide protection that is sufficient in the absence of something similar to an N95. Filtering The OS Respirator utilizes a modular filter design, which simply means it is compatible with any of the filtering materials listed below:
Face mask The seal of the face mask greatly impacts the efficacy of any respirator [3]. Users should make adjustments to get the best fit for their face. Heat gun, hair dryer, or adjusting the CAD model before printing are all effective ways to adjust the OS Respirator. Resources [1] Center for Devices and Radiological Health. (n.d.). N95 Respirators and Surgical Masks (Face Masks). Retrieved from https://www.fda.gov/medical-devices/personal-protective-equipment-infection-control/n95-respirators-and-surgical-masks-face-masks [2] Davies, A., Thompson, K.-A., Giri, K., Kafatos, G., Walker, J., & Bennett, A. (2013). Testing the Efficacy of Homemade Masks: Would They Protect in an Influenza Pandemic? Disaster Medicine and Public Health Preparedness, 7(4), 413–418. doi: 10.1017/dmp.2013.43 [3] Sande, M. V. D., Teunis, P., & Sabel, R. (2008). Professional and Home-Made Face Masks Reduce Exposure to Respiratory Infections among the General Population. PLoS ONE, 3(7). doi: 10.1371/journal.pone.0002618 [4] Tellier, R. (2006). Review of Aerosol Transmission of Influenza A Virus. Emerging Infectious Diseases, 12(11), 1657–1662. doi: 10.3201/eid1211.060426 |
Jacob Nichols
I am a Biomedical Engineering student, STEM-lover, and Maker. I enjoy developing 3D models that can be created with rapid prototyping technologies like 3D printers. |