Example: The Biomedical Benefit
The diagram on the right illustrates that wrist-worn optical heart rate monitors (OHRMs) are generally considered less accurate than the basic chest strap HR monitors, notwithstanding that OHRMs are built with multiple LEDs and Photodetectors running with advanced algorithms.
Such shortcomings of the wrist-worn OHRMs can be attributed to its lower signal-to-noise ratio (SNR), a result of the OHRMs having a noisy power supply bias that causes significant interference toward the LEDs and Photodetectors
A traditional approach is to add more LEDs and Photodetectors to the OHRMs, and pump more current to increase the SNR. But in real-world conditions, it is evident that multiple LEDs (and Photodetectors) and the highest input current (or highest SNR) are not necessarily the most optimal performance. It is ineffective while detrimentally on power consumption.
In weak signal conditions, the significance of SNR varies depending on the quality of the dynamic range, especially when the required signal is near to or overlaps with the background noise. OHRM is an excellent example in this scenario.
On the contrary, TransSiP PI Enhanced OHRMs offer accuracy equivalent to the chest straps, even with a single LED and Photodetector. Using a Harmony PI filter is essential to clean out all noise in the supply bias to the LED, AFE, Photodetector, and Current ADC as illustrated in the following diagram.
Furthermore, the following illustrates OHRMs are considered clinically acceptable, and TransSiP PI Enhanced OHRMs achieved all that.
Percentage of time the OHRM provides a heart rate deviation not more than ±10 bpm:
§ 98% for sedentary activities
§ 95% during the most intense activity (i.e., running)
§ 92% of the time in the least periodic activity (i.e., gym)
Limits of agreement (LoA):
§ the difference between the OHRM and the chest strap HR: ±15 bpm.
The overall errors,
§ the mean absolute error (MAE) ≤ 3bpm
§ The standard error of the estimate (SEE) ≤ 10bpm
To Summarize:
TransSiP PI targets the other side of the OHRM problem: the noisy power supply bias
By removing a considerable amount of the interfering noise, TransSiP PI is able to enhance the accuracy of wrist-worn OHRMs to match powerful chest strap HR monitors while also improving overall power consumption and system performance.
TransSiP PI Enhanced Optical Biosensor could be equivalent and, therefore, a valid alternative to chest strap HR.
TransSiP PI empowers a broad range of optical-based biomedical monitoring.