Week 3 HRV Iteration

Iteration 3:

For this week we went about improving the HRV sensor by making it easier to take readings of our heartrate. A large problem with the previous design was the constant changing of the range between the peaks of our values; one person's peaks and lows could be 800 and 500 on a certain spot on their finger while being 900 and 600 between another, making a change in the code necessary for the HRV to work. We were supplied with code which let us scale the peak values at will with the press of the A button, partially fixing the issue of the hassle involved in getting proper readings off of the HRV sensor.

New Code:

On start the HRV declares all of its variables and connects to the pulse sensor via pin P2 on our breadboards.


 

The forever loop turns a light on and off at the 2,2 coordinate at every heartbeat recorded, giving us a visual indication of if the HRV is properly calibrated with its peaks and valleys and remains unlit if uncalibrated.


 

The code for pressing button A is responsible for the calibration, setting the values for peaks and valleys of our pulse to ones recorded by the HRV sensor in the moment of pressing the button, in the common cases of the HRV not being calibrated properly during testing.


 

The main code responsible for the entire application working properly. It calculates the time between peaks (delta t), visualizes the heart rate on the microbit in the fashion of a bar chart and detects the peaks/valleys using if statements which compare their values to the observed maximum and minimum ones (the ones we can tweak using button A).



And finally, code below is responsible for data gathering and visualizing said data on graphs, giving us proper feedback during testing.


 

Reflection on HRV tests:

A good sign of the HRV working is it not flatlining while connected to us. From the testing done and in the video below, a stable heartrate is one which forms a sinewave, regardless of if you're doing breathing exercises holding your breath etc, a stable heartrate should always be moving up and down slightly.

Youtube Recording of Text

 Issues Pertaining to Taking Measurements:

A persisting issue and one which we are working on now that we have manual calibration working with the help of the new code, is that of actually using the sensor with ease without having to constantly find good spots to attach it to your finger and doing your best not to move. A 3d printed clip for your finger was proposed, and I myself tried to work on attaching a small layer transluscent material between the sensor and your finger, so that the tightness of the HRV would become a non issue, as from my understanding the sensor works using light, but I couldn't get it to work properly and I think the clip will work much better as that seems to be the standard for devices like this in hospitals.

Comments

Post a Comment

Popular posts from this blog

Iteration 2 | Jack | HRV Micro:bit Research

Image
Iteration #2 - Micro: Bit Research & HRV Jack Duggan | 20094010 | IOT Apps For the second iteration sprint of the module, I got hands-on with the Micro:bit. I had previously used these devices way back in secondary school for Leaving Certificate Computer Science, so the basics came back to me fairly quickly. We were sent home to 'research' the Micro:bit, and become familiar with it's basic functionality, before class on Friday the 2nd of February. In the class, I worked alone (as we had an odd number of students present) with a Micro:bit V2, an expansion board for the Microbit, and a heart rate sensor. Above is the physical setup Below is the device output screen with my finger on the sensor. The top graph shows my pulse as analogue input as identified by the sensor. Some mathematics is performed (as shown under the below graph) that converts these pulse values to HRV (delta_t). This HRV value is then displayed on the 'boxier looking' graph underneath. The way t...
Read more

Iteration 5.2 | Lock In | Jack

Image
Iteration 5.2 | The Lock-In 🔒 Jack Duggan | 20094010 | 10/05/2024 The "lock-in" was something initially devised months ago, an idea that involved taking a couple of days towards the end of the semester to commit fully to this module. As the semester began to wind up in terms of general workload, it became increasingly apparent that this "lock-in" would be necessary. In week 10/11 when we finally set it in stone, it was a great relief off all of all shoulders, knowing it was one less module to stress about, especially with already rampant workload due in week 12/13. With the lock-in pencilled in for the second week of May, it allowed myself and the others to put increased focus on other modules, and helped reduce the stresses we faced at this time. Eventually, the lock-in week did come around, and I and the others arrived in the room on Tuesday 7th May at 10am sharp. We had split into two teams, one team consisting of Emma, Conor and Eric that would look at adding H...
Read more

Week 1: HRV Review

Image
  What is it? Heart rate variability (HRV) is the measure of the variation between heartbeats. It is controlled by your autonomic nervous system (ANS). This system operates automatically and regulate process such as the heart rate and other bodily functions that are are not under conscious control. This system is broken into two branches the flight or fight (which preparing the body for action and stress) and the rest + digest (which promotes relaxation + recovery). HRV is influenced by the ability to smoothly shift between these two branches.  High HRV: Larger difference between successive heartbeats - Indicates a more flexible and adaptable autonomic nervous system.  Low HRV: Smaller differences between successive heartbeats - Indicates a less flexible autonomic nervous system.                                                ...
Read more