Utah-Stanford Ventilator (Vent4US): Developing a rapidly scalable ventilator for COVID-19 patients with ARDS

Hongquan Li; Ethan Li; Deepak Krishnamurthy; Patrick Kolbay; Beca Chacin; Soeren Hoehne; Jim Cybulski; Lara Brewer; Tomasz Petelenz; Joseph Orr; Derek Sakata; Thomas Clardy; Kai Kuck; Manu Prakash

respiratory rate, as well as assist control where a breath of set tidal volume can be triggered by the patient. The linear actuator ( Figure 4A ) compresses a segment of 1/4" OD, 1/8" ID silicone tubing (hardness: Shore A45) by variable amounts to achieve flow control. At an inlet pressure of 15 psi, we found that a 3 mm actuation is sufficient for valve flow to transition from a completely closed state to a completely open state ( Figure 4B and 4C), with the completely open state allowing the maximum flow rate of 50 L/min. We also demonstrated both slow and fast actuation cycles of the valve ( Figure 4D and 4E, at actuation rates for fully-closed to fully-open cycles up to 5 Hz). We measured the valve's response time (time it takes for flow to reach 95% of its maximum value) to be 48˘8 ms ( Figure 4F ). Finally we tested the repeatability of the valve's proportional flow control by measuring the flow rate as a function of valve state ( Figure 4G ). The valve was found to be fairly repeatable, with the flow rate at a given valve state having a maximum variability of around 5% at the highest flow rates. Repeatability can be further improved by incorporating an encoder or a Hall effect limit switch.