KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Search Results

Now showing 1 - 5 of 5

Some of the metrics are blocked by your
consent settings
Pulse Oximetry Based on Quadrature Multiplexing of the Amplitude Modulated Photoplethysmographic Signals
(2023-07-01)
Koseeyaporn, Jeerasuda
;
Wardkein, Paramote
;
Sinchai, Ananta
;
Kainan, Pattana
;
Tuwanut, Panwit
In this research, a pulse oximeter based on quadrature multiplexing of AM-PPG signals is proposed. The oximeter is operated by a microcontroller and employs a simple amplitude modulation technique to mitigate noise interference during SpO<inf>2</inf> measurement. The two AM-PPG signals (RED and IR) are quadrature multiplexed using carrier signals with equal frequencies but a 90-degree phase difference. The study focused on noise interference caused by light intensity and hand movement. The experiment was conducted under three different levels of light intensity: 200 Lux, 950 Lux, and 2200 Lux. For each light intensity level, the SpO<inf>2</inf> level was measured under three scenarios: hand still, shadow movement over the hand, and hand shaking. A comparison between the proposed technique and the conventional method reveals that the proposed technique offers a superior performance. The relative error of the measured SpO<inf>2</inf> level using the proposed technique was less than 3.1% overall. Based on the study, the proposed technique is less affected by noise interference caused by light intensity and hand movement compared to the conventional method. In addition, the proposed technique has an advantage over contemporary methods in terms of computational complexity. Consequently, the proposed technique can be applied to wearable devices that include SpO<inf>2</inf> measurement functionality.
Some of the metrics are blocked by your
consent settings
New pulse oximetry detection based on the light absorbance ratio as determined from amplitude modulation indexes in the time and frequency domains
(2022-05-01)
Kainan, Pattana
;
Sinchai, Ananta
;
Tuwanut, Panwit
;
Wardkein, Paramote
The Pandemic COVID-19 situation, a pulse Oximetry is significant to detect a varying blood oxygen saturation of a patient who needed the device to operate with continuous, rapid, high accuracy, and immune of moving artifacts. In this article, three main schemes for low-complexity pulse oximetry detection are proposed. In the first scheme, the light absorbance ratio (R) is obtained by separating the red and infrared photoplethysmography (PPG) amplitude modulation (AM) signals from the frequency-division multiplexing (FDM) signal with two different bandpass filters (BPFs), determining the ratio of modulation index of red and infrared PPG AM signals. In the second scheme, the output PPG AM signals for the red and infrared light wavelengths from the BPFs are transformed into the frequency domain such that the AC components of both PPG AM signals are the magnitudes of the highest peaks in their respective sidebands, while the DC components are the magnitude of their carrier frequencies; then, the AC/DC ratio of the red PPG AM signal is divided by the AC/DC ratio of the infrared PPG AM signal is R. In the last scheme, the FDM signal is transformed into the frequency domain without being passed through any BPF, and R is obtained in the same way as in the same second scheme. Experimental results obtained by using the first scheme have an average error of about 0.7138%, for the second and the last scheme have an average error of about 1%, and all the methods agree with the corresponding mathematical model.
Some of the metrics are blocked by your
consent settings
Fully Digital Cosine Signal Driven Pulse Oximeter Without Bandpass Filter Based on Microcontroller
(2022-04-20)
Kainan, Pattana
;
Wiriyatanachit, Supatsara
;
Rungkrae, Manussawee
;
Wardkein, Paramote
;
Maneerat, Noppadol
In this research, almost fully digital microcontroller pulse oximeter processing by two frequencies of cosine wave-driven red and infrared light sources as well as direct recovering photoplethysmography (PPG) signals from FDM signal without bandpass filter with coherent amplitude demodulation is proposed. An ESP32 microcontroller is employed to generate two cosine waves with two difference equation algorithms instead of using the function of cosine from Arduino or C library language. Two frequency digital cosine wave signals are generated and converted to analog signals with D/A to drive two light sources while two digital cosine signals as mentioned above are recognized in order to use to be as two local oscillator cosine wave signals for recovery of two PPG signals with synchronous demodulation. The RED and IR PPG signals are later used to estimate blood oxygen saturation (SpO2). The experimental result shows that it works well with accuracy and precision of 99.4448% and 0.5551, respectively.
Some of the metrics are blocked by your
consent settings
Fully Digital Pulse Oximeter Cosine Wave Driven Generate two PPG AMs and AM Synchronous Detector with Single Microcontroller
(2022-01-01)
Kainan, Pattana
;
Rungkrae, Manussawee
;
Wiriyatanachit, Supatsara
;
Wardkein, Paramote
;
Lertterada, Krittapas
In this article, an embedded microcontroller ESP32 implement to be a pulse oximeter is proposed. The almost overall system operates on a microcontroller except for the analog front-end trans-impedance amplifier. The system works by generating two different frequency cosines with cosine function and converting them to be analog cosine signals to drive IR and Red-light sources. The two PPG AM signals are summed in FDM form at the output of the light detector, and it is amplified and converted to be digital signal by the microcontroller after that the digital signal as mentioned above is selected by two digital BPFs with different center frequencies and two PPG AMs are obtained. Two PPG AMs have been demodulated with AM synchronous detector therefore the PPG IR and PPG RED are obtained. They are employed to estimate oxygen saturated and display on OLED along with mobile devices android OS by Bluetooth communication channel. The experiment results show that the proposed system can well operate and have accuracy and precision are 98.1261% and 0.9031, respectively.
Some of the metrics are blocked by your
consent settings
A Photoplethysmographic Signal Isolated from an Additive Motion Artifact by Frequency Translation
(2018-08-01)
Sinchai, Sakkarin
;
Kainan, Pattana
;
Wardkein, Paramote
;
Koseeyaporn, Jeerasuda
Acquiring a precise percentage of oxygen saturation (SpO2) from a finger-probe pulse oximeter is dependent on both artifact-free red and infrared photoplethysmoghaphic (PPG) signals. Nonetheless, in real-life situations, these PPG signals are corrupted by a motion artifact (MA) signal that is generated from either finger or hand movement. To resolve this MA interference, the cause of the adulteration of PPG signals by the MA signal is examined. The MA signal is found to behave like an additive noise. Additionally, the frequency responses of the MA and PPG signals show that these signals are in the same frequency band. Hence, instead of direct current, a sinusoidal wave alternating current is proposed to drive an LED source in order to shift the PPG frequency band away from the MA frequency band. Experimentally, a commercial finger-probe pulse oximeter is employed. To determine the performance of the presented scheme, the resulting PPG signals are compared with those from employing the old-fashioned LED-driving method. In addition, the accuracy is verified by computing the SpO2 value. The results reveal that the proposed approach successfully retains the fundamental morphologies of the PPG structures when motion occurs. Moreover, the calculated SpO2 values from the proposed technique provide an average error of approximately 1.4%, whereas the conventional method yields a mean error approximately 4.2%.

KMITL

Browse

Filters

Settings

Sort By

Results per page

Search Results