Development of a Wearable Reflection-Type Pulse Oximeter System to Acquire Clean PPG Signals and Measure Pulse Rate and SpO2 with and without Finger Motion
Abstract
:1. Introduction
2. Related Works
3. Our Contribution
- We propose an electronic circuit using an analog filter that contributes to acquire clean PPG signals.
- To measure SpO2, our proposed system interfaces with an optocoupler, which serves to separate the red and green LED signals.
- Generally, it is known that a single cycle of the PPG signal can be used to measure PR. However, our experiments showed that the pulse period for each PPG cycle was not the same. Hence, we propose an algorithm that can detect similar periods of PPG cycles, which we call “true” PPG signals. In this manuscript, our proposed PR measurement algorithm also helps in distinguishing the true PPG signals from the sequential PPG signals.
- We also consider three kinds of finger motions while measuring PR. By increasing the moving average window for processing the PPG signals, we mitigate the finger motion artifact noise. This feature can be used for monitoring seriously ill patients.
- We show possible applications of our proposed wearable PO device as a wearable, hand-held device, and clean PPG signal acquisition system through USB to serial communication.
- To use our proposed wearable PO device as a hand-held PO device, we design a smartphone app that can be used to monitor PR and SpO2 through a Bluetooth connection between the smartphone and device.
4. Proposed Method
4.1. Proposed Electronic Circuit for PPG Signal Acquisition
4.2. Proposed PR and SpO2 Measurement Algorithm
4.3. Analyzing and Removing Finger Motion Artifact
5. Hardware Implementation
6. Results and Discussion
6.1. MAPE
6.2. MAE
6.3. RCF
6.4. Evaluation of the Proposed Electronic Circuit
7. Possible Application of Our Proposed Wearable PO Device
8. Conclusions
Author Contributions
Funding
Conflicts of Interest
References
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Serial No. | Component Name | Characteristics | Manufacturer |
---|---|---|---|
01 | Red LED, 5730 SMD LED | Operating voltage: 1.9–2.1 V, wavelength: 620–625 nm, maximum power dissipation: 0.5 W, light intensity: 14–16 lumen. | Cam Farm |
02 | Green LED, 5730 SMD LED | Operating voltage: 3.1–3.2 V, wavelength: 520–525 nm, maximum power dissipation: 0.5 W, light intensity: 20–25 lumen. | Cam Farm |
03 | PD, VEMD5510 C | Operating maximum reverse voltage: 20 V, dark current: 0.2–10 nA, maximum power dissipation: 215 mW, peak sensitivity: 550 nm, spectral bandwidth: 440–700 nm. | Vishay Semiconductor Opto Division |
04 | Op-amp, AD623 AN | Operating voltage: 2.7–12 V, power dissipation: 650 mW, slew rate: 0.3 V/µs, gain: 1–1000. | Analog Devices Inc. |
05 | Optocoupler, ILQ1, quad channel | Maximum forward current: 60 mA, LED forward voltage: 1.25–1.65 V, collector-emitter saturation voltage: 0.25–0.4 V, current transfer ratio: 20–300%, power dissipation: 250 mW, propagation delay high to low: 0.7 µs, propagation delay low to high: 1.4 µs. | Vishay Semiconductor Opto Division |
06 | Battery charging IC, TP4056 | Operating voltage: 4–8 V, regulated output voltage: 4.137–4.263 V, charging current up to 1000 mA, charge threshold 2.9 V. | NanJing Top Power ASIC Corp. |
07 | MCU, ESP-WROOM-32 | Two CPU cores, CPU clock frequency: 80–240 MHz, operating voltage: 2.7–3.6 V, operating average current: 80 mA, Bluetooth protocols: v4.2, and Wi-Fi protocols: 802.11 n up to 150 Mbps. | Espressif Systems |
08 | Resistors | 55 Ω, 82 Ω, 1 KΩ, 100 KΩ, 330 KΩ. | Cheil Electronics |
09 | Capacitors | 3.3 µF (electrolytic), 0.1 µF (ceramic). | SAMWON |
10 | Lithium Polymer Battery, TW451635 | Voltage supply: 3.7 V, capacity: 200 mAh, power rating: 0.74 W. | The Han Co., Ltd. |
11 | Adafruit 1.3 inch TFT display, ST7789, 240 × 240 | Operating voltage: 3.3–5 V, 16-bit full-color pixels, pixel density: 260 ppi. | ADAFRUIT |
Subject | MAPE (%) | MAE (bpm) | RCF | SpO2 (%) (Our) | SpO2 (%) (Reference) |
---|---|---|---|---|---|
1 | 5.60 | 3.94 | 0.96 | 97.33 | 99 |
2 | 4.14 | 3.61 | 0.96 | 99.25 | 98 |
3 | 4.16 | 3.12 | 0.97 | 97.63 | 97 |
4 | 2.80 | 2.13 | 0.97 | 95.27 | 96 |
5 | 3.87 | 3.06 | 0.96 | 96.00 | 96 |
6 | 3.15 | 2.18 | 0.97 | 96.59 | 95 |
7 | 0.27 | 0.22 | 0.99 | 95.97 | 97 |
8 | 2.44 | 1.93 | 0.98 | 98.13 | 97 |
9 | 1.70 | 1.36 | 0.98 | 98.24 | 96 |
10 | 1.75 | 1.14 | 0.98 | 99.00 | 99 |
11 | 3.22 | 2.14 | 0.97 | 98.09 | 98 |
12 | 0.02 | 0.01 | 0.99 | 99.03 | 97 |
13 | 3.57 | 2.77 | 0.97 | 94.87 | 95 |
14 | 2.18 | 1.19 | 0.98 | 96.11 | 94 |
15 | 3.37 | 2.48 | 0.97 | 97.34 | 97 |
Subject | MAPE (%) | MAE (bpm) | RCF | SpO2 (%) (Our) | SpO2 (%) (Reference) |
---|---|---|---|---|---|
1 | 7.89 | 6.46 | 0.95 | 92.12 | 98 |
2 | 8.85 | 7.82 | 0.92 | 91.55 | 97 |
3 | 6.78 | 5.59 | 0.94 | 94.18 | 99 |
4 | 4.13 | 3.22 | 0.96 | 98.57 | 96 |
5 | 1.23 | 0.96 | 0.99 | 95.89 | 96 |
6 | 7.43 | 6.16 | 0.93 | 92.44 | 96 |
7 | 3.36 | 2.65 | 0.97 | 97.54 | 99 |
8 | 1.82 | 1.67 | 0.98 | 98.88 | 98 |
9 | 7.64 | 6.80 | 0.93 | 93.12 | 98 |
10 | 5.85 | 3.69 | 0.96 | 96.19 | 99 |
11 | 2.96 | 2.18 | 0.97 | 96.45 | 98 |
12 | 0.56 | 0.40 | 0.99 | 94.96 | 97 |
13 | 7.13 | 8.94 | 0.94 | 92.59 | 97 |
14 | 3.31 | 1.88 | 0.98 | 95.45 | 97 |
15 | 5.39 | 4.07 | 0.96 | 94.55 | 97 |
Subject | MAPE (%) | MAE (bpm) | RCF | SpO2 (%) (Our) | SpO2 (%) (Reference) |
---|---|---|---|---|---|
1 | 7.89 | 6.46 | 0.95 | 92.12 | 98 |
2 | 8.85 | 7.82 | 0.92 | 91.55 | 97 |
3 | 6.78 | 5.59 | 0.94 | 94.18 | 99 |
4 | 4.13 | 3.22 | 0.96 | 98.57 | 96 |
5 | 1.23 | 0.96 | 0.99 | 95.89 | 96 |
6 | 7.43 | 6.16 | 0.93 | 92.44 | 96 |
7 | 3.36 | 2.65 | 0.97 | 97.54 | 99 |
8 | 1.82 | 1.67 | 0.98 | 98.88 | 98 |
9 | 7.64 | 6.80 | 0.93 | 93.12 | 98 |
10 | 5.85 | 3.69 | 0.96 | 96.19 | 99 |
11 | 2.96 | 2.18 | 0.97 | 96.45 | 98 |
12 | 0.56 | 0.40 | 0.99 | 94.96 | 97 |
13 | 7.13 | 8.94 | 0.94 | 92.59 | 97 |
14 | 3.31 | 1.88 | 0.98 | 95.45 | 97 |
15 | 5.39 | 4.07 | 0.96 | 94.55 | 97 |
Subject | MAPE (%) | MAE (bpm) | RCF | SpO2 (%) (Our) | SpO2 (%) (Reference) |
---|---|---|---|---|---|
1 | 7.13 | 6.22 | 0.92 | 90.06 | 97 |
2 | 5.61 | 5.45 | 0.93 | 92.79 | 96 |
3 | 5.91 | 4.42 | 0.96 | 95.63 | 99 |
4 | 0.10 | 0.07 | 0.99 | 95.39 | 95 |
5 | 0.49 | 0.36 | 0.99 | 96.11 | 96 |
6 | 2.16 | 1.53 | 0.98 | 94.85 | 96 |
7 | 6.41 | 5.19 | 0.99 | 90.31 | 96 |
8 | 7.67 | 7.16 | 0.96 | 89.72 | 97 |
9 | 8.47 | 6.85 | 0.96 | 88.89 | 97 |
10 | 1.93 | 1.31 | 0.98 | 98.93 | 99 |
11 | 4.24 | 3.10 | 0.96 | 96.50 | 98 |
12 | 1.53 | 1.12 | 0.98 | 98.84 | 98 |
13 | 5.86 | 4.56 | 0.95 | 92.41 | 96 |
14 | 2.99 | 1.78 | 0.98 | 96.41 | 98 |
15 | 6.51 | 5.53 | 0.97 | 90.26 | 97 |
Condition | Subject | MAPE (%) | MAE (bpm) | RCF | SpO2 Accuracy (%) | ||||
---|---|---|---|---|---|---|---|---|---|
Our | FPO | Our | FPO | Our | FPO | Our | FPO | ||
Without motion | 1 | 3.60 | 3.45 | 2.73 | 2.39 | 0.97 | 0.98 | 99.51 | 99.89 |
2 | 6.28 | 5.77 | 4.96 | 4.33 | 0.95 | 0.97 | 99.60 | 99.12 | |
3 | 3.26 | 3.44 | 2.25 | 2.39 | 0.97 | 0.96 | 98.73 | 98.86 | |
4 | 0.39 | 1.27 | 0.31 | 1.35 | 0.99 | 0.98 | 96.90 | 95.73 | |
5 | 2.44 | 3.13 | 1.92 | 2.66 | 0.98 | 0.97 | 96.90 | 96.22 | |
6 | 2.20 | 1.77 | 1.76 | 1.34 | 0.98 | 0.99 | 95.83 | 97.41 | |
Left–right finger motion | 1 | 9.63 | 9.22 | 5.31 | 4.9 | 0.92 | 0.94 | 95.55 | 96.39 |
2 | 3.27 | 8.36 | 2.55 | 8.11 | 0.97 | 0.93 | 96.44 | 91.32 | |
3 | 6.73 | 8.12 | 4.40 | 7.22 | 0.95 | 0.92 | 96.17 | 92.57 | |
4 | 4.12 | 9.67 | 3.25 | 9.13 | 0.96 | 0.91 | 98.98 | 94.73 | |
5 | 8.78 | 10.15 | 7.20 | 9.68 | 0.93 | 0.9 | 97.95 | 94.19 | |
6 | 7.28 | 11.37 | 5.60 | 10.55 | 0.94 | 0.87 | 98.04 | 93.89 | |
Up-down finger motion | 1 | 4.88 | 5.62 | 3.56 | 4.78 | 0.96 | 0.94 | 95.83 | 91.73 |
2 | 1.95 | 2.32 | 1.41 | 1.98 | 0.98 | 0.96 | 96.77 | 90.56 | |
3 | 3.81 | 8.77 | 2.70 | 7.97 | 0.97 | 0.94 | 96.25 | 93.78 | |
4 | 7.59 | 10.11 | 5.52 | 8.91 | 0.94 | 0.89 | 97.95 | 91.33 | |
5 | 3.59 | 9.65 | 2.84 | 8.74 | 0.97 | 0.91 | 95.83 | 88.48 | |
6 | 8.94 | 13.55 | 7.69 | 11.29 | 0.92 | 0.84 | 98.37 | 89.77 | |
Round-up finger motion | 1 | 0.33 | 5.48 | 0.25 | 4.67 | 0.99 | 0.93 | 94.73 | 87.71 |
2 | 9.61 | 13.12 | 7.21 | 12.42 | 0.92 | 0.88 | 96.90 | 93.05 | |
3 | 5.49 | 10.16 | 3.90 | 8.78 | 0.96 | 0.9 | 95.83 | 89.09 | |
4 | 8.81 | 11.58 | 7.09 | 10.37 | 0.92 | 0.88 | 97.57 | 91.88 | |
5 | 8.67 | 16.62 | 8.16 | 15.22 | 0.91 | 0.85 | 96.90 | 84.43 | |
6 | 7.98 | 19.11 | 6.70 | 18.61 | 0.94 | 0.81 | 95.75 | 85.67 |
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Banik, P.P.; Hossain, S.; Kwon, T.-H.; Kim, H.; Kim, K.-D. Development of a Wearable Reflection-Type Pulse Oximeter System to Acquire Clean PPG Signals and Measure Pulse Rate and SpO2 with and without Finger Motion. Electronics 2020, 9, 1905. https://doi.org/10.3390/electronics9111905
Banik PP, Hossain S, Kwon T-H, Kim H, Kim K-D. Development of a Wearable Reflection-Type Pulse Oximeter System to Acquire Clean PPG Signals and Measure Pulse Rate and SpO2 with and without Finger Motion. Electronics. 2020; 9(11):1905. https://doi.org/10.3390/electronics9111905
Chicago/Turabian StyleBanik, Partha Pratim, Shifat Hossain, Tae-Ho Kwon, Hyoungkeun Kim, and Ki-Doo Kim. 2020. "Development of a Wearable Reflection-Type Pulse Oximeter System to Acquire Clean PPG Signals and Measure Pulse Rate and SpO2 with and without Finger Motion" Electronics 9, no. 11: 1905. https://doi.org/10.3390/electronics9111905
APA StyleBanik, P. P., Hossain, S., Kwon, T.-H., Kim, H., & Kim, K.-D. (2020). Development of a Wearable Reflection-Type Pulse Oximeter System to Acquire Clean PPG Signals and Measure Pulse Rate and SpO2 with and without Finger Motion. Electronics, 9(11), 1905. https://doi.org/10.3390/electronics9111905