This virtual issue of ACS Sensors on wearable sensing devices gives a taste of the current state of the art in this exciting field. Papers selected from the period 2020–2022 showcase the interdisciplinary nature of wearable sensors, where engineering, materials chemistry, analytical chemistry, electrochemistry, applied spectroscopy, microfluidics, bioanalysis, physics, data science, and medicine all form important elements of progress. ACS Sensors has published a number of reviews and perspective articles on wearable sensing systems that are not included in this virtual issue. (1−7) It is a productive and developing research field and for this reason this virtual issue can unfortunately not be comprehensive. The 29 publications shown here have been selected to showcase the breadth of methodologies, materials, and analytical targets reported in this journal. To date, wearables have been developed for a diversity of reasons. Perhaps the most active application area has been in health monitoring, with a wide range of wearables being used to observe activity, physiology, and environment in real time. Innovative advances in the recognition and sensing of a wide range of target analytes have been reported, often using electrochemistry as a low power method. In beautiful work by Ganguly and co-workers, aptamer-modified electrodes were used to detect cortisol in sweat by electrochemical impedance spectroscopy, suggesting that continuous on-body measurements for up to 8 h are possible. (8) Electrochemical detection of nicotine in sweat was demonstrated by Javey and colleagues, coupling a nicotine oxidizing enzyme to a nanodentrite-modified electrode. (9) In addition, vitamin C in sweat was detected by Joseph Wang’s team through enzymatic degradation and the use of an oxygen electrode to monitor oxygen loss upon enzyme conversion. (10) Lastly, Crespo and co-workers presented an enzymatic electrochemical lactate sensor, where the analyte flux was restricted with a plasticized polymeric membrane covering the enzyme layer, thereby improving robustness and ensuring that the signal is less prone to enzyme loss. (11) Elegant studies have also leveraged spectroscopy for readout. For example, Mitsubayashi and colleagues were able to optically image ethanol emanating from the skin with nicotinamide adenine dinucleotide-dependent alcohol dehydrogenase embedded in a mesh. The reaction yields fluorescent NADH that provides real-time, spatially resolved ethanol concentration information about various locations on the skin. (12) Variations in glucose on the skin were also detected using fluorescence by Wu and co-workers, using two luminescent nanomaterials, of which one is degraded by the hydrogen peroxide product of the glucose oxidase enzyme reaction, thereby turning the fluorescence on. (13) Subcutaneous measurements of pH and lactate were measured continuously by Nguyen et al. using fluorescence and a simple LED light source. (14) For lactate, an oxygen sensor was used that tracked diminished oxygen upon enzymatic conversion of lactate, which is in some way analogous to Wang’s work described above. In other exciting studies, Quan Liu’s group demonstrated the enzyme-free detection of subcutaneous glucose by surface enhanced Raman Spectroscopy using monolayer-covered silver coated arrays, with results on rat models being successfully validated. (15) Finally, a completely wireless glucose sensing approach was reported by Christopher Reiche’s group, where boronic acid modified hydrogels were implanted and observed by a routine medical ultrasound transducer. (16) Variable glucose concentration was found to swell the hydrogel in real time at a specific tunable frequency, with the results also being successfully cross-correlated. From an engineering perspective, wearable sensors come in a wide variety of forms. These include patches, tattoos, facemasks, contact lenses, fabrics, bandages, spectacles, and watches. While the choice of format is often dictated by the analyte or property to be measured and the environment in which the sensor should function, other factors such as operational lifetime, discreteness, and the complexity of the decision-making process are equally as important. That said, the careful selection of substrate material is always key to creating a successful wearable sensor, since the material must facilitate sensing, while also possessing a range of other features, which may include flexibility, toughness, processability, biodegradability, and transparency. In this regard, Luo and co-workers have described a flexible patch for continuous blood glucose level monitoring that integrates biodegradable microneedles. (17) In a similar vein, Müller et al. fabricated acrylate-based microneedle arrays to measure oxygen within the interstitial fluid of the skin. (18) In both studies, the biocompatibility of the sensor is a critical issue in engendering long-term in vivo use. Conversely, Zhu and colleagues have used commercial contact lens materials to fabricate smart contact lenses able to perform wireless intraocular pressure measurements, using a spectacle-integrated impedance-based reader. (19) Highly stretchable substrate materials for the realization of head-band integrated potentiometric sensors for sweat monitoring were reported by Xu and co-workers, demonstrating minimal signal change upon stretching the device 200%. (20) Interestingly, Bae and colleagues recently introduced a simple method for making stretchable optical waveguides from elastomers. These form the basis of wearable optical sensors (integrating LEDs, heaters, and photodetectors) and have been successfully used to monitor heart rate, breathing, and blood oxygen saturation. (21) Due to its low cost and availability, paper is particularly interesting for single use colorimetric applications, where test outcome can be read by eye or a smartphone. That said, integrating flow control in an efficient and low-cost manner can be challenging. To address this issue, Vaquer et al. integrated dissolvable polymer valves within a wearable urea biosensor that detects pH of sweat over extended time periods. (22) While many wearable sensors have been developed to monitor basic physical properties, such as temperature, pressure, and motion, the analysis of bodily fluids (e.g., sweat, urine, interstitial fluid, and breath) requires more sophisticated processing and thus necessitates the integration of functional components within the sensor construct. Fluidic manipulations are perhaps foremost in this regard, with the sensor needing to manipulate fluids in an efficient but passive manner. Some excellent examples of fluidic integration have been published in ACS Sensors over the past two years. For example, Vinoth and co-workers fabricated wearable microfluidic sensors that enable the electrochemical monitoring of sweat biomarkers during exercise. (23) Here, fluidic channels are used to rapidly capture and direct sweat to sensing electrodes, allowing the electrochemical detection of ions and pH. In a similar manner, Hozumi and colleagues developed a flexible sensor for the simultaneous monitoring sweat glucose, heart activity, and skin temperature. (24) The ability to perform such measurements in real time was enabled by the use of a fluidic channel that refreshes sweat over the sensor surface. Additionally, Choi et al. reported the development of a multilayer capacitive sweat rate sensor, integrating a central microfluidic channel to allow real-time sweat rate monitoring without the need for microfabricated electrodes. (25) In a related study, Saha and colleagues presented a continuous sweat lactate sensor, integrating osmotic sweat extraction, paper-based microfluidics (to control sweat transport), and a screen-printed electrochemical sensor. This work is notable since the sensor enables the continuous monitoring of sweat lactate during both rest and exercise. (26) More recently, Zhang and associates described a clever fabric-based microfluidic wearable for calcium monitoring in sweat. (27) Here, the authors infused laser-cut thermoplastic films into fabrics to form integrated microfluidic circuits, that were effective in delivering sweat toward screen-printed electrodes. This work is especially exciting, since it suggests a simple route toward mass production of smart clothing in the future. Finally, it is interesting to see activity in the development of smart bandages for wound status monitoring. Two excellent examples in this regard have been reported by Charkhabi and Liu. In the former study, an LC-resonator is embedded in a commercial dressing and used to monitor wound healing in a rat cohort. (28) In the latter, a multiplexed sensing bandage was used for the real-time monitoring of sodium, potassium, calcium, pH, uric acid, and temperature to provide an early diagnostic of infection and inflammation. (29) From a materials perspective, recent years have seen the incorporation of a range of advanced functional materials within wearable sensors. Compelling examples in this regard include the use of copper-based MOFs (metal organic frameworks) on freestanding titania nanochannels for the chemiresistive sensing of nitric oxide at ppb levels, (30) a bifunctional gas sensor incorporating gold nanoparticle-modified Au InSe nanosheets for real-time monitoring of atmospheric ammonia and nitrogen dioxide, (31) a neuron-mimic gas sensor (comprising gold quantum dots on Bi₂S₃ nanosheets) for the sensitive detection of nitrogen dioxide, (32) a porous PDMS capacitive pressure sensor for head trauma assessment, (33) and MXene-based resistive tattoos as sensitive strain sensors for the continuous monitoring of pulse rate, respiration rate, and muscle response. (34) Finally, a desirable feature of any wearable sensor is that it should be small and ideally unobtrusive. While the sensor itself may fit the bill, the ability to miniaturize the power supply is often more problematic. One solution to this problem is to harvest (and store) energy from the wearer or environment using thermoelectric materials. Using such an idea, Li and co-workers have recently presented a self-powered, fabric-based temperature sensor. (35) The sensor comprises layers of compressible spacer fabric and thermoelectric material (PEDPT:PSS), and is able to sense both temperature and pressure variations with excellent resolution and response times. More importantly, the power needed to drive the sensor is generated by the temperature difference between the wearer and the environment. Moreover, Zhang and colleagues have developed biodegradable facemasks for respiratory disease diagnosis. (36) Their sensor, based on a polylactic acid electret fabric and carbon paper electrode layer, is able to successfully diagnose individuals suffering from asthma, bronchitis, and chronic obstructive pulmonary disease within a few minutes. Importantly, the facemasks are simple to make, comfortable to wear, and integrate portable readout circuitry. To conclude, we hope that you will agree that wearable sensor research continues to thrive and evolve. Indeed, our only wish was that we could have included more papers in this virtual issue. Regardless, we hope that you will enjoy the collection and appreciate the exceptional science and technology. This article references 36 other publications. This article has not yet been cited by other publications. This article references 36 other publications.

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可穿戴传感器

可穿戴传感设备上的ACS 传感器这一虚拟问题让我们领略了这个令人兴奋的领域的最新技术水平。选自 2020-2022 年期间的论文展示了可穿戴传感器的跨学科性质，其中工程学、材料化学、分析化学、电化学、应用光谱学、微流体学、生物分析、物理学、数据科学和医学都是进步的重要元素。ACS 传感器已发表多篇关于可穿戴传感系统的评论和观点文章，但未包含在本期虚拟期刊中。(1−7) 这是一个富有成效且不断发展的研究领域，因此，不幸的是，这个虚拟问题可能并不全面。此处显示的 29 篇出版物已被选中，以展示该期刊报告的方法、材料和分析目标的广度。迄今为止，出于多种原因开发了可穿戴设备。也许最活跃的应用领域是健康监测，大量可穿戴设备被用于实时观察活动、生理和环境。据报道，在广泛的目标分析物的识别和传感方面取得了创新进展，通常使用电化学作为低功率方法。在 Ganguly 及其同事的精美作品中，适配体修饰的电极被用于通过电化学阻抗谱检测汗液中的皮质醇，这表明连续进行长达 8 小时的体表测量是可能的。(8) Javey 及其同事证明了汗液中尼古丁的电化学检测，将尼古丁氧化酶偶联到纳米树突修饰的电极上。(9) 此外，Joseph Wang 的团队通过酶促降解和使用氧电极监测酶转化时的氧损失来检测汗液中的维生素 C。(10) 最后，Crespo 和同事展示了一种酶促电化学乳酸传感器，其中分析物通量受到覆盖酶层的塑化聚合物膜的限制，从而提高稳健性并确保信号不易被酶损失。(11) 优雅的研究还利用光谱学进行读出。例如，Mitsubayashi 及其同事能够通过嵌在网状物中的烟酰胺腺嘌呤二核苷酸依赖性乙醇脱氢酶对皮肤散发的乙醇进行光学成像。该反应产生荧光 NADH，提供关于皮肤上不同位置的实时、空间分辨的乙醇浓度信息。(12) Wu 和同事还使用荧光检测了皮肤上葡萄糖的变化，使用两种发光纳米材料，其中一种被葡萄糖氧化酶反应的过氧化氢产物降解，从而打开荧光。(13) Nguyen 等人连续测量了 pH 值和乳酸的皮下测量值。使用荧光和简单的 LED 光源。(14) 对于乳酸，使用氧传感器跟踪乳酸酶促转化时减少的氧气，这在某种程度上类似于 Wang 的上述工作。在其他激动人心的研究中，刘权的团队展示了使用单层覆盖的银涂层阵列通过表面增强拉曼光谱法对皮下葡萄糖进行无酶检测，结果在大鼠模型上得到了成功验证。(15) 最后，Christopher Reiche 的小组报告了一种完全无线的葡萄糖传感方法，其中硼酸改性水凝胶被植入并通过常规医学超声换能器进行观察。(16) 发现可变葡萄糖浓度以特定的可调频率实时溶胀水凝胶，结果也成功地相互关联。从工程角度来看，可穿戴传感器有多种形式。这些包括贴片、纹身、面罩、隐形眼镜、织物、绷带、眼镜和手表。虽然格式的选择通常取决于要测量的分析物或特性以及传感器应在其中运行的环境，但其他因素（例如使用寿命、离散性和决策过程的复杂性）同样重要。也就是说，仔细选择基板材料始终是成功打造可穿戴传感器的关键，因为该材料必须便于传感，同时还具有一系列其他功能，其中可能包括柔韧性、韧性、加工性、生物降解性和透明度。在这方面，Luo 及其同事描述了一种用于连续监测血糖水平的柔性贴片，它集成了可生物降解的微针。(17) 同样，Müller 等人。制造基于丙烯酸酯的微针阵列来测量皮肤间质液中的氧气。(18) 在这两项研究中，传感器的生物相容性是产生长期影响的关键问题。制造基于丙烯酸酯的微针阵列来测量皮肤间质液中的氧气。(18) 在这两项研究中，传感器的生物相容性是产生长期影响的关键问题。制造基于丙烯酸酯的微针阵列来测量皮肤间质液中的氧气。(18) 在这两项研究中，传感器的生物相容性是产生长期影响的关键问题。体内使用。相反，Zhu 及其同事使用商用隐形眼镜材料制造了智能隐形眼镜，该隐形眼镜能够使用基于阻抗的眼镜集成阅读器进行无线眼内压测量。(19) Xu 及其同事报告了用于实现汗液监测头带集成电位传感器的高度可拉伸基板材料，表明在将设备拉伸 200% 时信号变化最小。(20) 有趣的是，Bae 及其同事最近介绍了一种用弹性体制造可拉伸光波导的简单方法。这些构成了可穿戴光学传感器（集成 LED、加热器和光电探测器）的基础，并已成功用于监测心率、呼吸和血氧饱和度。(21) 由于其低成本和可用性，纸张对于一次性比色应用特别有趣，测试结果可以通过肉眼或智能手机读取。也就是说，以高效且低成本的方式集成流量控制可能具有挑战性。为了解决这个问题，Vaquer 等人。在可穿戴尿素生物传感器中集成可溶解聚合物阀，可长时间检测汗液的 pH 值。(22) 虽然已经开发出许多可穿戴传感器来监测基本的物理特性，例如温度、压力和运动，但体液（例如汗液、尿液、间质液和呼吸）的分析需要更复杂的处理，因此有必要传感器构造中功能组件的集成。在这方面，流体操作可能是最重要的，传感器需要以高效但被动的方式操纵流体。流体积分的一些优秀示例已发表在ACS 传感器在过去的两年里。例如，Vinoth 和同事制造了可穿戴微流体传感器，可以在运动过程中对汗液生物标志物进行电化学监测。(23) 在这里，流体通道用于快速捕获汗液并将其引导至传感电极，从而实现离子和 pH 值的电化学检测。Hozumi 及其同事以类似的方式开发了一种灵活的传感器，用于同时监测汗液葡萄糖、心脏活动和皮肤温度。(24) 实时执行此类测量的能力是通过使用流体通道来刷新传感器表面的汗液而实现的。此外，Choi 等人。报道了多层电容式出汗率传感器的开发，集成中央微流体通道，无需微加工电极即可实时监测出汗率。(25) 在一项相关研究中，Saha 及其同事展示了一种连续汗液乳酸传感器，它集成了渗透式汗液提取、纸基微流体（用于控制汗液传输）和丝网印刷电化学传感器。这项工作值得注意，因为传感器可以在休息和运动期间连续监测汗液乳酸。(26) 最近，Zhang 及其同事描述了一种巧妙的基于织物的微流体可穿戴设备，用于监测汗液中的钙。(27) 在这里，作者将激光切割的热塑性薄膜注入织物中，形成集成微流体电路，可有效地将汗液输送到丝网印刷电极。这项工作特别令人兴奋，因为它为未来智能服装的大规模生产提供了一条简单的途径。最后，有趣的是看到用于伤口状态监测的智能绷带的开发活动。Charkhabi 和 Liu 在这方面报告了两个很好的例子。在前一项研究中，LC 谐振器嵌入商业敷料中，用于监测大鼠队列的伤口愈合情况。(28) 在后者中，使用多路传感绷带实时监测钠、钾、钙、pH、尿酸和温度，以提供感染和炎症的早期诊断。(29) 从材料的角度来看，近年来在可穿戴传感器中结合了一系列先进的功能材料。₂秒₃纳米片）用于二氧化氮的灵敏检测，（32）用于头部外伤评估的多孔 PDMS 电容式压力传感器，（33）和基于 MXene 的电阻纹身作为用于连续监测脉搏率、呼吸率和肌肉的灵敏应变传感器回复。(34) 最后，任何可穿戴传感器的一个理想特征是它应该很小并且最好不显眼。虽然传感器本身可能符合要求，但小型化电源的能力往往更成问题。解决这个问题的一种方法是使用热电材料从佩戴者或环境中收集（并储存）能量。利用这样的想法，Li 及其同事最近提出了一种基于织物的自供电温度传感器。(35) 传感器包括多层可压缩间隔织物和热电材料（PEDPT:PSS），并且能够以出色的分辨率和响应时间感测温度和压力变化。更重要的是，驱动传感器所需的功率是由佩戴者与环境之间的温差产生的。此外，Zhang 及其同事还开发了用于呼吸系统疾病诊断的可生物降解面罩。(36) 他们的传感器基于聚乳酸驻极体织物和碳纸电极层，能够在几分钟内成功诊断出患有哮喘、支气管炎和慢性阻塞性肺病的个体。重要的是，面罩制作简单，佩戴舒适，并集成了便携式读出电路。最后，我们希望您同意可穿戴传感器研究继​​续蓬勃发展和发展。的确，我们唯一的希望是我们可以在这个虚拟问题中包含更多论文。无论如何，我们希望您会喜欢这个系列并欣赏卓越的科学技术。本文引用了 36 篇其他出版物。这篇文章尚未被其他出版物引用。本文引用了 36 篇其他出版物。