• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 춘계종합학술대회 A
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• pp.495-498
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• 2008

본 논문은 유비쿼터스 헬스케어 시스템을 위한 웨어러블 센서의 한 종류로서, 손목 착용형 $SpO_2$ 모듈을 구현하였으며 사용자의 산소포화도를 모니터링 할 수 있도록 제안하였다. $SpO_2$ 계측 보드는 고성능, 저전력 특징을 가지고 있는 MCU (ATmega128L, Atmel Co., USA)를 활용하여 모든 측정된 신호의 처리 및 제어를 담당하도록 하였으며, 일차적인 신호의 증폭과 필터를 위한 아날로그 회로도 구성하였다. 또한, 특정부위에서의 측정을 위해 제작된 반사형 프로브와도 연결되어 측정된 신호의 수집 및 처리를 담당하도록 하였다. IEEE 802.15.4 표준 프로토콜과 연동이 가능한 무선 센서 노드는 $SpO_2$ 계측 보드와 함께 연결되어 수집된 데이터를 서버측 PC로 전송하는 역할을 담당한다. 제안된 시스템의 활용으로 관리자가 서버측에서 모니터링 프로그램을 통해 사용자의 건강상태에 대한 정보를 확보할 수 있도록 하였다.

• Journal of Electrical Engineering and Technology
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• 제9권5호
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• pp.1780-1787
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• 2014

Arterial oxygen saturation ($SpO_2$) monitoring for newborns requires special attention in neonatal intensive care units (NICUs). Newborns have very low photo-plethysmogram (PPG) amplitudes and their body movements are difficult to contain. Hardware design and its associated signal processing algorithms should be robust enough so that faulty measurements can be avoided. In this study, improved designs were implemented to deal with low perfusion, motion artifact, and the influence of ambient light. Dynamic range was increased by using different LED intensities and a feedback system. To minimize the effects of motion artifact and to discard other unqualified data, four additional algorithms were used, which were based on dual-trace detection, continuity of DC level, morphology of PPG, and simultaneity check of $SpO_2$. Our $SpO_2$ system was tested with newborns with normal respiration in the NICU. Our system provided fast, real-time responses and 100% artifact detection was accomplished under 84% of $SpO_2$.

• 전기전자학회논문지
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• 제18권1호
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• pp.172-178
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• 2014

이 논문은 산소 포화도 측정을 위하여 설계되는 아날로그 프런트 엔드의 설계 기술 및 디자인 방법에 관한 것이다. 센서로부터 출력되는 데이터를 이용하여 산소포화도를 계산하기 위해서는 센서의 포토다이오드에서 흘려주는 전류 데이터를 전압 데이터로 바꿔주는 것이 필요하다. 설계된 아날로그 프런트 엔드는 센서로부터 출력되는 전류 데이터를 여러 가지 전압 이득을 가지는 형태로 후방의 아날로그 디지털 변환기에 전압을 전달하는 역할을 한다. 설계된 회로는 $0.11{\mu}m$ CMOS공정을 이용하여 설계되었으며, $0.174mm^2$의 면적을 차지한다.

• IEIE Transactions on Smart Processing and Computing
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• 제6권2호
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• pp.129-132
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• 2017

A conventional pulse oximeter has high power consumption; thus, its mobility is severely limited. In this paper, we discuss the drawbacks of the existing pulse oximeters and propose a new ultra-low-power pulse oximeter that supports wireless data transmission for remotely monitoring vital signs, such as peripheral capillary oxygen saturation (SpO2) and beats per minute (BPM). We could notably reduce power consumption by using a low-frequency single clock in all well-customized modules. Also, our device is publicly certified, and thus, possibly engaged in clinical trials for commercial use.

• Journal of Oral Medicine and Pain
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• 제48권3호
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• pp.96-105
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• 2023

Purpose: Mandibular advancement devices (MAD) are known to be insufficiently effective in all patients with obstructive sleep apnea (OSA). This study aimed to compare the treatment outcomes of MAD therapy according to OSA severity and to investigate the risk factors for the lack of response to MAD therapy. Methods: A total of 29 patients diagnosed with OSA received an adjustable two-piece MAD treatment. Sleep parameters measured with the home sleep apnea test device, including apnea-hypopnea index (AHI) and oxygen saturation (SpO₂), and daytime sleepiness using the Epworth Sleepiness Scale (ESS) were retrospectively assessed both before and after the MAD treatment. Results: The patients were classified into three groups according to AHI severity: mild (n=16, AHI<15), moderate (n=6, 15≤AHI<30), and severe OSA (n=7, AHI≥30). MAD therapy significantly improved the sleep parameters (p<0.001 for AHI and p=0.004 for minimum SpO₂) and daytime sleepiness (p<0.001 for ESS). Furthermore, successful outcomes (reduction in AHI>50% and AHI<10 events/h) were achieved in 83.3% and 71.4% of moderate and severe OSA cases, respectively. Of 13 patients with moderate and severe OSA, 10 were classified as responders and 3 as non-responders. The non-responders had significantly lower baseline value of SpO₂ (p=0.049 for average SpO₂ and p=0.007 for minimum SpO₂) and higher baseline AHI (p=0.049) than the responders. Conclusions: The results of the present study suggest that MAD is effective in the majority of patients with OSA of varying severities. The success of MAD therapy does not seem to depend solely on AHI severity. In addition to AHI, minimum SpO₂ may be a prognostic measure of the efficacy of MAD treatment in clinical dental practice.

• 전기전자학회논문지
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• 제20권1호
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• pp.115-118
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• 2016

본 논문은 고령자 고독사를 방지하기 위한 알람 시스템 개발에 대한 논문이다. 최근 고령자 인구는 급속도로 증가되고 있다. 이에 따라 고령자의 고독사에 대한 문제가 사회적으로 대두되고 있다. 이에 본 논문에서는 독거노인의 상태를 알려주는 알람 시스템을 개발한다. 이 시스템은 고령자의 산소포화도와 맥박을 연속적으로 측정하며, 고령자의 위급한 상황에 대해 가족과 이웃에게 알려 줄 수 있는 시스템이다. 이러한 시스템을 검증하기 위해 본 논문에서는 SpO2 시뮬레이터를 이용하였다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2015년도 추계학술발표대회
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• pp.578-579
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• 2015

Transmission and reflectance are two non-invasive techniques to perform pulse oximetry. This paper presents a design of reflectance-based pulse oximetry for watch-type wearable device, in which sensor and detector are located on the same surface of the body part. The basic principle of a pulse oximeter is based on the measurement of the red and infrared (IR) light absorption. Oxygenated blood has significant differences of light absorption characteristics than deoxygenated blood under red (660 nm) and infrared (940 nm) wavelength. Infrared is absorbed more by oxygenated hemoglobin than red. So the hardware implementation is included placing of the two LEDs (red and IR) with single photo-detector in the middle on the patient's wrist to get the corresponding pulsatile signals which are used to estimate the $SpO_2$.

• 센서학회지
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• 제27권3호
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• pp.192-198
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• 2018

Pulse oximetry is a non-invasive method for monitoring how much oxygenated hemoglobin is present in the blood. The principle of pulse oximetry is based on the red infrared light adsorption characteristics of oxygenated and deoxygenated hemoglobin. Even through the convenience of a pulse oximeter, its weak signal-to-noise ratio against motion artifacts and low perfusion makes it difficult to be accepted by execs devices. Several researchers have suggested the use of an adaptive noise cancellation (ANC) algorithm. They have demonstrated that ANC is feasible for reducing the effects of motion artifacts. Masimo Corporation developed a discrete saturation transformation (DST) algorithm that uses a reference signal and ANC. In commercial devices, it is very hard to escape it because Masimo's patents are very powerful and a better method is yet to be developed. This study proposes a new method that can measure noise saturation as well as accurate oxygen saturation from signals with high motion artifacts without using ANC and DST. The proposed algorithm can extract a normal signal without noise from a signal with motion artifacts. The reference signal from a pulse oximeter simulator was used for the evaluation of our proposed algorithm and achieved good results.

• 대한임상검사과학회지
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• 제43권4호
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• pp.188-193
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• 2011

Obstructive sleep apnea (OSA) is the most common type of sleep apnea and is caused by obstruction of the upper airway. Since it is closely related to sleep parameter and body indices, the study was focused on the relationship with them. The results of polysomnography (PSG) in obstructive sleep apnea was done at ENT department of Ewha women university Mokdong hospital from March to September 2010 with 52 subjects (male 35, female 17). The leads were placed to measure electroencephalogram (EEG), electrooculogram (EOG), mandibular and anterior tibialis electromyogram (EMG), airflow in nasal and oral cavity, chest and abdominal breathing pattern, snoring sound and arterial oxygen saturation ($SpO_2$) level. From sleep parameter and body indices of adult obstructive sleep apnea compared to normal adult revealed that age (p<0.01) and snoring sound (p<0.05) were increased, stage 1 sleep (p<0.01) was increased, the deeper stages (3&4) of sleep (p<0.05) were reduced. Respiratory disturbance index (RDI) (p<0.01), mean $SpO_2$ (p<0.05) and lowest $SpO_2$ (p<0.01) were also decreased. The correlation analysis from sleep parameter and body indices of OSA showed the positive correlation with age (r=0.463, p<0.001), snoring sound (r=0.278, p<0.05), stage 1 sleep (r=0.391, p<0.01) and RDI (r=0.409, p<0.01), but showed the negative correlation with the deeper stages (3&4) of sleep (r=-0.307, p<0.05), mean $SpO_2$=(r=-0.274, p<0.05) and lowest $SpO_2$ (r=-0.392, p<0.01). This study proves that obstructive sleep apnea and indices have closed related.

• 대한의용생체공학회:의공학회지
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• 제22권5호
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• pp.431-438
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• 2001

동맥혈액의 총 혈색소 농도와 산화 혈색소 농도의 비율로 정의되는 산소포화도를 비관혈적으로 측정하는 펄스 옥시메터는 주위환경 요인과 피측정자의 호흡 및 움직임에 의한 영향을 받는다. 특히 환자가 움직였을 때 동잡음 신호는 주파수영역에서 정상적인 수신광 신호와 중첩 또는 인접하게 나타나 잡음제거가 어렵다 이러한 문제점을 개선하기 위해 본 논문에서는 필터뱅크와 정합필터를 이용하여 동잡음을 제거하기 위한 방법을 제안한다. 그리고 제안된 방법으로 실험한 결과. ratio의 평균 변화율이 이동평균필터(11.2%)와 적응필터(39.7%)를 이용하였을 때 보다 변화 폭이 4.1%로 나타나 환자의 움직임에서도 보다 안정적인 산소포화도를 측정이 가능할 것으로 사료된다.