Commit 75239c4f authored by Zach Fredin's avatar Zach Fredin

add'l diagram

parent 230dd080
......@@ -16,7 +16,11 @@ The apparatus also records raw analog sensor data from the commercial pulse oxim
![rawdata_sensors_zoomed_more](../img/rawdata_sensors_zoomed_more.png)
The blue plot, representing the commercial (Zacurate-brand) device uses more of the A/D converter's 0-3.3 VDC range, and doesn't have the slow rise time of the fabricated sensor (orange plot). In both lines, the fast pair of pulses show the photodiode response to the IR and red LED signal. See the Background section for more information on how these sensors work, the Apparatus section for more information and code related to the first prototype, and [my NMM page](file:///home/zach/Documents/NMM/site/people/zach/final.html) for a look at data processing.
The blue plot, representing the commercial (Zacurate-brand) device uses more of the A/D converter's 0-3.3 VDC range, and doesn't have the slow rise time of the fabricated sensor (orange plot). In both lines, the fast pair of pulses show the photodiode response to the IR and red LED signal. Here is an early pass at an algorithm to calculate SpO<sub>2</sub> from the commercial device's signal (blue) compared to its displayed output (orange); the fabricated sensor is still a work-in-progress:
![zacurate_r_vs_spo2](../img/zacurate_r_vs_spo2.png)
See the Background section for more information on how these sensors work, the Apparatus section for more information and code related to the first prototype, and [my NMM page](file:///home/zach/Documents/NMM/site/people/zach/final.html) for a look at data processing.
### Next Steps
- iterate the sensor prototype
......@@ -26,7 +30,7 @@ The blue plot, representing the commercial (Zacurate-brand) device uses more of
- filtering, curve fitting, etc
### Questions
Is there a need for a crude, distributed-fab coronavirus early warning device? Something that, rather than giving an absolute SpO<sub>2</sub> reading, provides a go/no-go indication relative to an initial condition. The standard for commercial pulse-ox devices is master calibration in a clinical trial using human subjects that deliberately enter a hypoxic state. Instead, what about a cheap indicator that simply indicates the change in SpO<sub>2</sub> since its first measurement, using a green-yellow-red indication rather than a digital display? Such a device could be provided to patients to wear continuously upon hospital discharge (or an asymptomatic positive covid-19 test result), and would give them an indication when they need to call their doctor due to plunging blood oxygen content. Crucially, the device would be cheap and would not require specialized components, so it could be made easily anywhere.
Is there a need for a crude, distributed-fab coronavirus early warning device? Something that, rather than giving an absolute SpO<sub>2</sub> reading, provides a go/no-go indication relative to an initial condition. The standard for commercial pulse-ox devices is master calibration in a clinical trial using human subjects that deliberately enter a hypoxic state. Instead, what about a cheap indicator that simply indicates the change in SpO<sub>2</sub> since its first measurement, using a green-yellow-red indication rather than a digital display? Such a device could be provided to patients to wear continuously upon hospital discharge (or an asymptomatic positive covid-19 test result), and would give them an indication when they need to call their doctor due to plunging blood oxygen content. Crucially, the device would be cheap and would not require specialized components, so it could be made easily anywhere.
### References
- overview of pulse oximetry physics and engineering challenges from 1989: Tremper, Kevin K., and Steven J. Barker. "Pulse oximetry." Anesthesiology: The Journal of the American Society of Anesthesiologists 70.1 (1989): 98-108.
......
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment