Pulse

脉冲
  • 文章类型: Journal Article
    秘鲁蚕豆(PFB)作为营养丰富的传统美食,美味,和质地成分;然而,人们对它们的工业特性知之甚少。这项研究评估了物理化学,营养,PFB品种的技术功能特征:Verde,奎尔考,还有Peruanita.PFB表现出明显的物理特征,质量参数,和形态学。种皮的颜色图案和硬度是区分它们的主要参数。营养,所有三个样品均显示出高蛋白(23.88-24.88g/100g),具有高比例的必需氨基酸,高膳食纤维(21.74-25.28克/100克),矿物质含量。它们还含有多酚(0.79-1.25mgGAE/g)和类黄酮(0.91-1.06mgCE/g),具有抗氧化潜力(用于ABTS和DPPH测定的16.60-21.01和4.68-5.17µmolTE/g,分别)。通过XRD测量,鉴定了样品的半结晶性质,属于C型结晶形态。关于技术功能,PFB粉显示出很大的发泡能力,佛得角品种是最稳定的。样品之间的乳化能力相似,虽然Peruanita在加热过程中更稳定。用水加热后,PFB粉达到175至272cP之间的峰值粘度,和最终粘度在242和384cP之间。Quelcao和Verde在冷藏后形成了更坚固的凝胶。基于这些结果,PFB将有助于开发创新,营养丰富,和满足市场需求的健康产品。
    Peruvian fava beans (PFB) are used in traditional cuisine as a nutrient-rich, flavorful, and textural ingredient; however, little is known about their industrial properties. This study evaluated the physicochemical, nutritional, and techno-functional characteristics of PFB varieties: Verde, Quelcao, and Peruanita. PFB exhibited distinct physical characteristics, quality parameters, and morphology. The color patterns of the seed coat and the hardness were the main parameters for distinguishing them. Nutritionally, all three samples exhibited high protein (23.88-24.88 g/100 g), with high proportion of essential amino acids, high dietary fiber (21.74-25.28 g/100 g), and mineral content. They also contain polyphenols (0.79-1.25 mg GAE/g) and flavonoids (0.91-1.06 mg CE/g) with antioxidant potential (16.60-21.01 and 4.68-5.17 µmol TE/g for ABTS and DPPH assays, respectively). Through XRD measurements, the semi-crystalline nature of samples was identified, belonging to the C-type crystalline form. Regarding techno-functionality, PFB flours displayed great foaming capacity, with Verde variety being the most stable. Emulsifying capacity was similar among samples, although Peruanita was more stable during heating. Upon heating with water, PFB flours reached peak viscosities between 175 and 272 cP, and final viscosities between 242 and 384 cP. Quelcao and Verde formed firmer gels after refrigeration. Based on these results, PFB would be useful to developing innovative, nutritious, and healthy products that meet market needs.
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  • 文章类型: Journal Article
    提出了一种用于指尖信号检测和人体脉搏监测的柔性弧形微光纤布拉格光栅(mFBG)阵列三维触觉传感器。它基于三个mFBG阵列,该阵列嵌入弧形聚(二甲基硅氧烷)(PDMS)弹性体中,可以有效区分法向力,左力,通过监测三个mFBG的反射强度变化来获得正确的力。与传统的FBG传感器不同,该传感器通过检测光强度的变化来测量力,有效避免了温度变化对传感器性能的波长交叉敏感影响。这种设计策略简化了传感器结构,降低了系统复杂度和信号询问成本,增强了可靠性和实用性。通过系统的实验,我们成功地验证了传感器的优越性能,达到0.01N的最小检测力,为实际应用提供可靠的数据支持。此外,该传感器已用于准确监测人体脉搏。该传感器的成功制作和实验验证为其在机器人感知和人体生命信号检测等领域的广泛应用奠定了基础。
    A flexible arc-shaped micro-Fiber Bragg Grating (mFBG) array three-dimensional tactile sensor for fingertip signal detection and human pulse monitoring is presented. It is based on a three mFBGs array which is embedded in an arc-shaped poly (dimethylsiloxane) (PDMS) elastomer, which can effectively discriminate the normal force, left force, and right force by monitoring the reflected intensity variation of the three mFBGs. Different from the traditional FBG sensors, this sensor measures force by detecting changes in light intensity, effectively avoiding the wavelength cross-sensitivity impact of temperature variations on the sensor performance. This design strategy simplifies the sensor structure, reduces the system complexity and signal interrogation cost, and enhances reliability and practicality. Through systematic experiments, we successfully validated the sensor\'s superior performance, achieving a minimum detection force of 0.01 N and providing robust data support for practical applications. In addition, the sensor has been used to monitor human pulse accurately. The successful fabrication and experimental validation of this sensor lay a foundation for its widespread application in fields such as robot perception and human vital signal detection.
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  • 文章类型: Journal Article
    许多临床前结果已经得到证实,和临床结果验证了调制电热疗(mEHT)的优势。该方法除了利用热能吸收之外还利用电场的非热效应。调节有助于精确靶向和免疫原性破坏恶性细胞,这可能会产生类似疫苗接种的副作用。新的附加调制(高功率脉冲)进一步发展了mEHT的能力。我的目标是介绍脉冲治疗的优势以及它如何适应mEHT治疗。脉冲治疗增加了破坏选定肿瘤细胞的功效;它在体内更深处活跃,至少是能量传递的三倍。由于脉冲幅度恒定,吸收能量的剂量是更可控的。用于复氧和药物递送的诱导血流足够高,但没有增加恶性细胞扩散的风险那么高。短脉冲减少了表面吸收,使治疗更安全,并且脉冲中增加的功率允许减少提供必要剂量所需的治疗时间。
    Numerous preclinical results have been verified, and clinical results have validated the advantages of modulated electro-hyperthermia (mEHT). This method uses the nonthermal effects of the electric field in addition to thermal energy absorption. Modulation helps with precisely targeting and immunogenically destroying malignant cells, which could have a vaccination-like abscopal effect. A new additional modulation (high-power pulsing) further develops the abilities of the mEHT. My objective is to present the advantages of pulsed treatment and how it fits into the mEHT therapy. Pulsed treatment increases the efficacy of destroying the selected tumor cells; it is active deeper in the body, at least tripling the penetration of the energy delivery. Due to the constant pulse amplitude, the dosing of the absorbed energy is more controllable. The induced blood flow for reoxygenation and drug delivery is high enough but not as high as increasing the risk of the dissemination of malignant cells. The short pulses have reduced surface absorption, making the treatment safer, and the increased power in the pulses allows the reduction of the treatment time needed to provide the necessary dose.
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  • 文章类型: Journal Article
    电化学高级氧化是一种有吸引力的使用点地下水处理选择,用于去除污染物,如1,4-二恶烷,这是难以通过使用传统的基于分离的技术去除。这项研究解决了在实际地下水处理中采用电化学电池的关键挑战-长期运行的电极稳定性。本研究旨在通过显着延长实验时间尺度来模拟现实的环境情景。除了间歇式反应器之外,还测试一个流通池,并使用电导率相当于地下水的电解质。我们首先构建了一个坚固的钛低价氧化物纳米管网状电极,该电极既用作阳极又用作阴极。然后,我们实施了脉冲电解策略,其中在阳极循环期间产生活性氧。并且电极在阴极循环期间再生。在优化条件下,通过电池的单程处理(有效面积:2cm2)在5mAcm-2的低电流密度下连续运行100h以上,对合成地下水中的1,4-二恶烷的去除效率达到了显着的65-70%。水通量为6Lm-2h-1。在这项研究中开发的电化学电池和脉冲处理方案向实用的地下水处理技术提出了关键的进步。
    Electrochemical advanced oxidation is an appealing point-of-use groundwater treatment option for removing pollutants such as 1,4-dioxane, which is difficult to remove by using conventional separation-based techniques. This study addresses a critical challenge in employing electrochemical cells in practical groundwater treatment─electrode stability over long-term operation. This study aims to simulate realistic environmental scenarios by significantly extending the experimental time scale, testing a flow-through cell in addition to a batch reactor, and employing an electrolyte with a conductivity equivalent to that of groundwater. We first constructed a robust titanium suboxide nanotube mesh electrode that is utilized as both anode and cathode. We then implemented a pulsed electrolysis strategy in which reactive oxygen species are generated during the anodic cycle, and the electrode is regenerated during the cathodic cycle. Under optimized conditions, single-pass treatment through the cell (effective area: 2 cm2) achieved a remarkable 65-70% removal efficiency for 1,4-dioxane in the synthetic groundwater for over 100 h continuous operation at a low current density of 5 mA cm-2 and a water flux of 6 L m-2 h-1. The electrochemical cell and pulse treatment scheme developed in this study presents a critical advancement toward practical groundwater treatment technology.
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  • 文章类型: Journal Article
    目的:心脏指数(CI)是确保儿科重症监护病房(PICU)最终器官灌注的关键生理参数。CI的确定需要进行有创心脏测量,并且通常不在PICU床边进行。迄今为止,没有黄金标准的非侵入性手段来确定CI。这项研究旨在使用一种新的非侵入性方法,基于常规的连续生理数据,称为脉搏到达时间(PAT)作为正常射血分数患者的替代指标。 方法:以每秒250个样本的采样频率从监视器旁边收集心电图(ECG)和光电血管容积图(PPG)信号。连续PAT,根据ECG和PPG波形对每位患者进行平均.计算PAT和CI、PAT和心率(HR)之间的Pearson相关系数,和PAT和射血分数(EF)。主要结果:20例患者接受了右心导管检查。患者平均年龄为11.7±5.4岁,从11个月到19岁不等,中位年龄为13.4岁.该队列中的HR为每分钟93.8±17.0次。平均EF为54.4±9.6%。平均CI为3.51±0.72L/min/m2,范围为2.6至4.77L/min/m2。平均PAT为0.31±0.12秒。Pearson相关分析显示PAT与CI呈正相关(0.57,p<0.01)。HR和CI之间的Pearson相关性以及EF和CI之间的相关性分别为0.22(p=0.35)和0.03(p=0.23)。PAT之间的相关性,当按HR(即PAT×HR)索引时,和CI最低改善至0.58(p<0.01)。&#xD;意义:这项初步研究表明,PAT可以作为床边CI的有价值的替代标记,作为PICU中的非侵入性和连续模式。PAT在临床实践中的使用仍有待彻底研究。 .
    Objective.Cardiac Index (CI) is a key physiologic parameter to ensure end organ perfusion in the pediatric intensive care unit (PICU). Determination of CI requires invasive cardiac measurements and is not routinely done at the PICU bedside. To date, there is no gold standard non-invasive means to determine CI. This study aims to use a novel non-invasive methodology, based on routine continuous physiologic data, called Pulse Arrival Time (PAT) as a surrogate for CI in patients with normal Ejection Fraction (EF).Approach.Electrocardiogram (ECG) and photoplethysmogram (PPG) signals were collected from beside monitors at a sampling frequency of 250 samples per second. Continuous PAT, derived from the ECG and PPG waveforms was averaged per patient. Pearson\'s correlation coefficient was calculated between PAT and CI, PAT and heart rate (HR), and PAT and EF.Main Results.Twenty patients underwent right heart cardiac catheterization. The mean age of patients was 11.7 ± 5.4 years old, ranging from 11 months old to 19 years old, the median age was 13.4 years old. HR in this cohort was 93.8 ± 17.0 beats per minute. The average EF was 54.4 ± 9.6%. The average CI was 3.51 ± 0.72 l min-1m-2, with ranging from 2.6 to 4.77 l min-1m-2. The average PAT was 0.31 ± 0.12 s. Pearson correlation analysis showed a positive correlation between PAT and CI (0.57,p< 0.01). Pearson correlation between HR and CI, and correlation between EF and CI was 0.22 (p= 0.35) and 0.03 (p= 0.23) respectively. The correlation between PAT, when indexed by HR (i.e. PAT × HR), and CI minimally improved to 0.58 (p< 0.01).Significance.This pilot study demonstrates that PAT may serve as a valuable surrogate marker for CI at the bedside, as a non-invasive and continuous modality in the PICU. The use of PAT in clinical practice remains to be thoroughly investigated.
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  • 文章类型: Journal Article
    界面电场在确定电催化过程中的极性分子构型和表面覆盖率方面具有重要意义。本研究介绍了一种在不同的界面电场强度下利用SO2变化的电偶极矩来增强SO2电还原过程的选择性的方法。这种方法首次尝试利用向Au/PTFE膜电极施加脉冲电压来控制电极表面上SO2的分子构型和覆盖率。值得注意的是,在毫秒脉冲条件下(ta=10ms,tc=300ms,Ea=-0.8V(相对于Hg/Hg2SO4),Ec=-1.8V(相对于Hg/Hg2SO4),伴随着H2S选择性的显著提高(FEH2S>97%)。综合分析,结合原位拉曼光谱,电化学石英晶体微天平,COMSOL模拟,和DFT计算,证实了H2S产物选择性的增加主要与SO2分子固有的大偶极矩有关。毫秒脉冲引起的界面电场的增强有助于放大SO2覆盖率,活化SO2,促进关键中间产物*SOH的形成,有效降低SO2还原过程中的反应能障。这些发现为离子和分子传输动力学的影响提供了新的见解,以及SO2电还原过程中竞争途径的时间复杂性。此外,它强调了电偶极矩与催化剂的表面-分子相互作用之间的内在相关性。
    Interfacial electric field holds significant importance in determining both the polar molecular configuration and surface coverage during electrocatalysis. This study introduces a methodology leveraging the varying electric dipole moment of SO2 under distinct interfacial electric field strengths to enhance the selectivity of the SO2 electroreduction process. This approach presented the first attempt to utilize pulsed voltage application to the Au/PTFE membrane electrode for the control of the molecular configuration and coverage of SO2 on the electrode surface. Remarkably, the modulation of pulse duration resulted in a substantial inhibition of the hydrogen evolution reaction (HER) (FEH2 < 3%) under millisecond pulse conditions (ta = 10 ms, tc = 300 ms, Ea = -0.8 V (vs Hg/Hg2SO4), Ec = -1.8 V (vs Hg/Hg2SO4)), concomitant with a noteworthy enhancement in H2S selectivity (FEH2S > 97%). A comprehensive analysis, incorporating in situ Raman spectroscopy, electrochemical quartz crystal microbalance, COMSOL simulations, and DFT calculations, corroborated the increased selectivity of H2S products was primarily associated with the inherently large dipole moment of the SO2 molecule. The enhancement of the interfacial electric field induced by millisecond pulses was instrumental in amplifying SO2 coverage, activating SO2, facilitating the formation of the pivotal intermediate product *SOH, and effectively reducing the reaction energy barrier in the SO2 reduction process. These findings provide novel insights into the influences of ion and molecular transport dynamics, as well as the temporal intricacies of competitive pathways during the SO2 electroreduction process. Moreover, it underscores the intrinsic correlation between the electric dipole moment and surface-molecule interaction of the catalyst.
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  • 文章类型: Journal Article
    鹰嘴豆和扁豆作物的农民一直在寻找具有更好建筑的精英品种,旨在使他们的机械化种植和收获系统化。因此,目前,与这些植物的分枝和结构调节相关的基因的鉴定已变得非常重要。在这里,这项工作旨在深入了解两个对比鹰嘴豆和扁豆品种在分枝模式方面的转录组变化(小分枝品种与高分枝品种)。此外,我们的目的是确定参与芽分枝调节的候选基因,这些基因可以用作分子育种的未来目标。鹰嘴豆品种Blancolechoso和FLIP07-318C的腋芽和顶芽,和小扁豆品种Castellana和Campisi,被认为是小而高度分支的,分别,被收获了。总共鉴定出1,624和2,512个转录本在鹰嘴豆和小扁豆的不同组织和对比品种之间差异表达,分别。几个基因类别被显著调节,如细胞周期,DNA转录,能量代谢,激素生物合成和信号,蛋白水解,鹰嘴豆和扁豆的顶端和腋窝组织之间的营养发育以及对比品种。基于差异表达和分支相关的生物学功能,十个鹰嘴豆基因和七个扁豆基因被认为是不同品种之间差异调节植物分枝的主要参与者。这些集体数据推测揭示了鹰嘴豆和小扁豆分枝调节的一般机制和高效应基因,它们是通过旨在改善植物结构的基因组编辑和转基因进行操作的潜在目标。
    The search for elite cultivars with better architecture has been a demand by farmers of the chickpea and lentil crops, which aims to systematize their mechanized planting and harvesting on a large scale. Therefore, the identification of genes associated with the regulation of the branching and architecture of these plants has currently gained great importance. Herein, this work aimed to gain insight into transcriptomic changes of two contrasting chickpea and lentil cultivars in terms of branching pattern (little versus highly branched cultivars). In addition, we aimed to identify candidate genes involved in the regulation of shoot branching that could be used as future targets for molecular breeding. The axillary and apical buds of chickpea cultivars Blanco lechoso and FLIP07-318C, and lentil cultivars Castellana and Campisi, considered as little and highly branched, respectively, were harvested. A total of 1,624 and 2,512 transcripts were identified as differentially expressed among different tissues and contrasting cultivars of chickpea and lentil, respectively. Several gene categories were significantly modulated such as cell cycle, DNA transcription, energy metabolism, hormonal biosynthesis and signaling, proteolysis, and vegetative development between apical and axillary tissues and contrasting cultivars of chickpea and lentil. Based on differential expression and branching-associated biological function, ten chickpea genes and seven lentil genes were considered the main players involved in differentially regulating the plant branching between contrasting cultivars. These collective data putatively revealed the general mechanism and high-effect genes associated with the regulation of branching in chickpea and lentil, which are potential targets for manipulation through genome editing and transgenesis aiming to improve plant architecture.
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  • 文章类型: Journal Article
    柔性传感器由于其在智能时代的巨大应用潜力而发展迅速。然而,频繁的弯曲工作要求对柔性传感器的机械可靠性提出了严峻的挑战。在这里,为了提高柔性压阻传感器的可靠性,首次提出了一种基于一个外部信号的多电极布局实现多传感信号的策略。多电极布局由一对叉指电极和底部电极组成。叉指电极用于感测传感器表面电阻的变化,叉指电极和底部电极用于感测传感器体电阻的变化。因此,在不增加传感单元面积的情况下,电极布局允许传感器在感应外部压力时产生三个响应电信号,从而提高了传感器的可靠性。根据电极布局,通过带有模板的微波发泡方法获得了具有多层多孔结构的高度可靠的柔性压阻传感器。在感应表面电阻的工作状态下,传感器具有22.12kPa-1的灵敏度。同时,在感应体电阻的工作状态下,传感器显示55.17kPa-1的灵敏度。此外,该传感器用于监测人体脉搏和语音信号,展示了它的多信号输出特性和在柔性电子中的潜在应用。总之,采用所提出的电极布局提高柔性传感器可靠性的新策略,有望大大促进柔性电子的实际应用。
    Flexible sensors have developed rapidly due to their great application potential in the intelligent era. However, the frequent bending work requirements pose a serious challenge to the mechanical reliability of flexible sensors. Herein, a strategy of using a new multielectrode layout to achieve multiple sensing signals based on one external signal is proposed for the first time to improve the reliability of flexible piezoresistive sensors. The multielectrode layout consists of a pair of interdigital electrodes and a bottom electrode. The interdigitated electrodes are used to sense the change in the surface resistance of the sensor, and the interdigital electrodes and the bottom electrode are used to sense the change in the bulk resistance of the sensor. As a result, without increasing the sensing unit area, the electrode layout allows the sensor to generate three response electrical signals when sensing an external pressure, thus improving the reliability of the sensor. Based on the electrode layout, a highly reliable flexible piezoresistive sensor with a multilevel porous structure is obtained by a microwave foaming method with a template. In the working state of sensing surface resistance, the sensor has a 22.12 kPa-1 sensitivity. Meanwhile, in the working state of sensing bulk resistance, the sensor shows a 55.17 kPa-1 sensitivity. Furthermore, the sensor is applied to monitor human pulse and speech signals, demonstrating its multisignal output characteristics and potential applications in flexible electronics. In conclusion, the new strategy of using the proposed electrode layout to improve the reliability of flexible sensors is expected to greatly promote the practical application of flexible electronics.
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  • 文章类型: Journal Article
    执行超声引导经股动脉入路(TFA)的新操作员的学习曲线仍然不确定。
    我们对FAUST(股动脉接入超声试验)和UNIVERSAL(心脏手术血管接入常规超声引导)试验进行了汇总分析,1:1超声引导和非超声引导TFA用于冠状动脉手术的两项多中心随机对照试验。结果包括大出血或血管并发症的复合以及成功的股动脉插管。参与者按操作员的应计病例量进行分层。我们使用调整后的重复测量逻辑回归,使用随机截获的运算符聚类,用于与非超声引导的TFA组进行比较并对学习曲线进行建模。
    FAUST和UNIVERSAL试验将总共1624名患者随机分组,其中810个被随机分配到非超声引导的TFA和814个被随机分配到超声引导的TFA(病例1-10,391;11-20,183;和>20,240)。具有>20个超声引导下TFA的操作者的参与者的主要终点风险降低(5/240[2.1%]对64/810[7.9%];调整后的比值比,0.26[95%CI,0.09-0.61])与非超声引导的TFA相比。进行了>20例超声引导手术的操作者成功插管股动脉的几率增加(224/246[91.1%]对327/382[85.6%];调整后的比值比,1.76[95%CI,1.08-2.89])与非超声引导的TFA相比。学习曲线图显示,随着累积案例的增加,能力不断提高。
    与非超声引导的TFA相比,新操作员应进行至少20次超声引导的TFA,以减少进入部位并发症并增加适当的插管。额外的应计案例可能会导致熟练程度的提高。培训计划应考虑跨radial时代的这些发现。
    UNASSIGNED: The learning curve for new operators performing ultrasound-guided transfemoral access (TFA) remains uncertain.
    UNASSIGNED: We performed a pooled analysis of the FAUST (Femoral Arterial Access With Ultrasound Trial) and UNIVERSAL (Routine Ultrasound Guidance for Vascular Access for Cardiac Procedures) trials, both multicenter randomized controlled trials of 1:1 ultrasound-guided versus non-ultrasound-guided TFA for coronary procedures. Outcomes included the composite of major bleeding or vascular complications and successful common femoral artery cannulation. Participants were stratified by the operators\' accrued case volume. We used adjusted repeated-measurement logistic regression, with random intercepts for operator clustering, for comparison against the non-ultrasound-guided TFA group and to model the learning curve.
    UNASSIGNED: The FAUST and UNIVERSAL trials randomized a total of 1624 patients, of which 810 were randomized to non-ultrasound-guided TFA and 814 to ultrasound-guided TFA (cases 1-10, 391; 11-20, 183; and >20, 240). Participants who had operators who performed >20 ultrasound-guided TFAs had a decreased risk for the primary end point (5/240 [2.1%] versus 64/810 [7.9%]; adjusted odds ratio, 0.26 [95% CI, 0.09-0.61]) compared with non-ultrasound-guided TFA. Operators who performed >20 ultrasound-guided procedures had increased odds of successfully cannulating the common femoral artery (224/246 [91.1%] versus 327/382 [85.6%]; adjusted odds ratio, 1.76 [95% CI, 1.08-2.89]) compared with non-ultrasound-guided TFA. The learning curve plots demonstrated growing competence with increasing accrued cases.
    UNASSIGNED: New operators should perform at least 20 ultrasound-guided TFA to decrease access site complications and increase proper cannulation compared with non-ultrasound-guided TFA. Additional accrued cases may lead to increased proficiency. Training programs should consider these findings in the transradial era.
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  • 文章类型: Journal Article
    背景:对于皮肤较黑的患者,许多商品脉搏血氧计的校准不足。我们通过对照实验证明了对外周血氧饱和度(SpO2)差异的定量测量。为了缓解这种情况,我们介绍OptoBeat,基于智能手机的超低成本光学传感系统,可捕获SpO2和心率,同时校准肤色差异。我们的传感系统可以由商品组件和3D打印夹子制成,价格约为1美元。在我们的实验中,我们展示了OptoBeat系统的功效,可以在低至75%的水平下测量实际值的1%以内的SpO2。
    目的:这项工作的目的是测试以下假设,并实施一种超低成本的智能手机适配器来测量SpO2:肤色对脉搏血氧计测量具有显着影响(假设1),肤色图像可用于校准脉搏血氧计误差(假设2),和SpO2可以用智能手机相机使用屏幕作为光源测量(假设3)。
    方法:在离体实验中使用与人皮肤具有相同光学性质的合成皮肤。将肤色标度放置在图像中用于校准和地面实况。为了实现广泛的SpO2测量,我们给羊血再充氧,然后通过合成动脉。将定制光学系统从智能手机屏幕(闪烁的红色和蓝色)连接到分析物,并连接到手机的相机以进行测量。
    结果:根据Fitzpatrick量表将3种肤色准确分类为2型、3型和5型。使用测量的红色之间的欧几里得距离进行分类,绿色,蓝色的价值观。传统的脉搏血氧计测量(n=2000)在使用ANOVA(直流电:F2,5997=3.1170×105,P<.01;交流电:F2,5997=8.07×106,P<.01)的交流电和直流电测量中显示出肤色之间的显著差异。连续SpO2测量(n=400;10秒样本,在离体实验中使用OptoBeat捕获总共67分钟)从95%到75%。通过二次支持向量机回归和10倍交叉验证(R2=0.97,均方根误差=0.7,均方误差=0.49,平均绝对误差=0.5),测量精度在基本事实的1%以内。在人类参与者概念验证实验中(N=3;样本=3×N,持续时间=每个样品20-30秒),SpO2测量的准确度在地面实况的0.5%以内,脉搏率测量的准确度在地面实况的1.7%以内。
    结论:在这项工作中,我们证明肤色对SpO2测量以及OptoBeat的设计和评估有显著影响。超低成本的OptoBeat系统使智能手机能够对肤色进行分类以进行校准,可靠地测量低至75%的SpO2,并标准化以避免基于肤色的偏见。
    BACKGROUND: Many commodity pulse oximeters are insufficiently calibrated for patients with darker skin. We demonstrate a quantitative measurement of this disparity in peripheral blood oxygen saturation (SpO2) with a controlled experiment. To mitigate this, we present OptoBeat, an ultra-low-cost smartphone-based optical sensing system that captures SpO2 and heart rate while calibrating for differences in skin tone. Our sensing system can be constructed from commodity components and 3D-printed clips for approximately US $1. In our experiments, we demonstrate the efficacy of the OptoBeat system, which can measure SpO2 within 1% of the ground truth in levels as low as 75%.
    OBJECTIVE: The objective of this work is to test the following hypotheses and implement an ultra-low-cost smartphone adapter to measure SpO2: skin tone has a significant effect on pulse oximeter measurements (hypothesis 1), images of skin tone can be used to calibrate pulse oximeter error (hypothesis 2), and SpO2 can be measured with a smartphone camera using the screen as a light source (hypothesis 3).
    METHODS: Synthetic skin with the same optical properties as human skin was used in ex vivo experiments. A skin tone scale was placed in images for calibration and ground truth. To achieve a wide range of SpO2 for measurement, we reoxygenated sheep blood and pumped it through synthetic arteries. A custom optical system was connected from the smartphone screen (flashing red and blue) to the analyte and into the phone\'s camera for measurement.
    RESULTS: The 3 skin tones were accurately classified according to the Fitzpatrick scale as types 2, 3, and 5. Classification was performed using the Euclidean distance between the measured red, green, and blue values. Traditional pulse oximeter measurements (n=2000) showed significant differences between skin tones in both alternating current and direct current measurements using ANOVA (direct current: F2,5997=3.1170 × 105, P<.01; alternating current: F2,5997=8.07 × 106, P<.01). Continuous SpO2 measurements (n=400; 10-second samples, 67 minutes total) from 95% to 75% were captured using OptoBeat in an ex vivo experiment. The accuracy was measured to be within 1% of the ground truth via quadratic support vector machine regression and 10-fold cross-validation (R2=0.97, root mean square error=0.7, mean square error=0.49, and mean absolute error=0.5). In the human-participant proof-of-concept experiment (N=3; samples=3 × N, duration=20-30 seconds per sample), SpO2 measurements were accurate to within 0.5% of the ground truth, and pulse rate measurements were accurate to within 1.7% of the ground truth.
    CONCLUSIONS: In this work, we demonstrate that skin tone has a significant effect on SpO2 measurements and the design and evaluation of OptoBeat. The ultra-low-cost OptoBeat system enables smartphones to classify skin tone for calibration, reliably measure SpO2 as low as 75%, and normalize to avoid skin tone-based bias.
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