Epidermal photonic devices for quantitative imaging of temperature and thermal transport characteristics of the skin

Gao, Li; Zhang, Yihui; Malyarchuk, Viktor; Jia, Lin; Jang, Kyung In; Webb, R. Chad; Fu, Haoran; Shi, Yan; Zhou, Guo‐Yan; Shi, Luke; Shah, Deesha; Huang, Xian; Xu, Baoxing; Yu, Cunjiang; Huang, Yonggang; Rogers, John A.

doi:10.1038/ncomms5938

Cited by 250 publications

(198 citation statements)

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“…[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] These novel epidermal devices contain soft, conformal sensors and associated circuits embedded in ultrathin encapsulating layers that achieve intimate skin coupling. 25,34 Here, we present a highly flexible epidermal design and clinical implementation of a novel ECG and heart rate logging wearable sensor, henceforth referred to as "WiSP", which is low cost, light-weight (1.2 g), and capable of energy harvesting.…”

Section: Introductionmentioning

confidence: 99%

Highly flexible, wearable, and disposable cardiac biosensors for remote and ambulatory monitoring

Lee¹,

Wright³

et al. 2018

npj Digital Med

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174

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Contemporary cardiac and heart rate monitoring devices capture physiological signals using optical and electrode-based sensors. However, these devices generally lack the form factor and mechanical flexibility necessary for use in ambulatory and home environments. Here, we report an ultrathin (~1 mm average thickness) and highly flexible wearable cardiac sensor (WiSP) designed to be minimal in cost (disposable), light weight (1.2 g), water resistant, and capable of wireless energy harvesting. Theoretical analyses of system-level bending mechanics show the advantages of WiSP's flexible electronics, soft encapsulation layers and bioadhesives, enabling intimate skin coupling. A clinical feasibility study conducted in atrial fibrillation patients demonstrates that the WiSP device effectively measures cardiac signals matching the Holter monitor, and is more comfortable. WiSP's physical attributes and performance results demonstrate its utility for monitoring cardiac signals during daily activity, exertion and sleep, with implications for home-based care.

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Section: Introductionmentioning

confidence: 99%

Highly flexible, wearable, and disposable cardiac biosensors for remote and ambulatory monitoring

Lee¹,

Wright³

et al. 2018

npj Digital Med

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174

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“…Here we describe recent advances in multimodal sensors of skin hydration, via measurements of intrinsic thermal and electrical properties, in which advanced materials, mechanics and concepts render devices that have soft, 'skin-like', or 'epidermal', formats [11][12][13][14][15][16][17][18][19][20] . The thin geometries and compliant mechanics lead to a mode of integration with the skin that does not require application of pressure, and instead relies on van der Waals adhesion forces alone.…”

Section: Introductionmentioning

confidence: 99%

Multimodal epidermal devices for hydration monitoring

et al. 2017

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Precise, quantitative in vivo monitoring of hydration levels in the near surface regions of the skin can be useful in preventing skinbased pathologies, and regulating external appearance. Here we introduce multimodal sensors with important capabilities in this context, rendered in soft, ultrathin, 'skin-like' formats with numerous advantages over alternative technologies, including the ability to establish intimate, conformal contact without applied pressure, and to provide spatiotemporally resolved data on both electrical and thermal transport properties from sensitive regions of the skin. Systematic in vitro studies and computational models establish the underlying measurement principles and associated approaches for determination of temperature, thermal conductivity, thermal diffusivity, volumetric heat capacity, and electrical impedance using simple analysis algorithms. Clinical studies on 20 patients subjected to a variety of external stimuli validate the device operation and allow quantitative comparisons of measurement capabilities to those of existing state-of-the-art tools.

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“…To realize scalable designs for multipoint measurements and/or to ensure sufficient accuracy of temperature measurement on dynamically moving objects due to strain-induced performance changes of sensors, however, it is important to significantly increase change of resistivity, ideally up to several orders-of-magnitude change. Although line-of-sight-based techniques including infrared thermographs and thermotropic liquid crystals (14) are capable of spatial temperature mapping, they require separation between the sensor and target object and, therefore, are unsuitable for implanted devices.…”

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confidence: 99%

Ultraflexible, large-area, physiological temperature sensors for multipoint measurements

Yokota

Inoue

Terakawa

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

337

298

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We report a fabrication method for flexible and printable thermal sensors based on composites of semicrystalline acrylate polymers and graphite with a high sensitivity of 20 mK and a high-speed response time of less than 100 ms. These devices exhibit large resistance changes near body temperature under physiological conditions with high repeatability (1,800 times). Device performance is largely unaffected by bending to radii below 700 μm, which allows for conformal application to the surface of living tissue. The sensing temperature can be tuned between 25°C and 50°C, which covers all relevant physiological temperatures. Furthermore, we demonstrate flexible active-matrix thermal sensors which can resolve spatial temperature gradients over a large area. With this flexible ultrasensitive temperature sensor we succeeded in the in vivo measurement of cyclic temperatures changes of 0.1°C in a rat lung during breathing, without interference from constant tissue motion. This result conclusively shows that the lung of a warm-blooded animal maintains surprising temperature stability despite the large difference between core temperature and inhaled air temperature. T emperature control plays a very important role in homeostasis, and body temperature varies both spatially and temporally in an effort to transfer heat between the living body and the environment via skin and respiratory organs. Accurate measurement of localized temperature changes in soft tissue regardless of large-scale motion is important in understanding thermal phenomena of homeostasis and realizing future sophisticated health diagnostics (1-3). Therefore, flexible temperature sensors which softly interface with tissue have been investigated frequently for applications in the medical field. However, these applications require the combination of sensitivity, fast response time, stability in physiological environments, and multipoint measurement. Before this work, to our knowledge, no experiment has simultaneously demonstrated orders-of-magnitude changes in electrical properties (sensitivity) repeatedly at varying physiological temperatures and conditions (stability) in a robust, easy-to-fabricate, flexible temperature sensor (processability).When sensors and electronics are directly attached to the surface of an animal body, the use of soft and flexible electronic devices is expected to reduce mechanical stress induced on the body. From this viewpoint, the field of flexible electronics has attracted much attention recently. The ability to gather information such as pressure and temperature from curvilinear and dynamic surfaces without impairing the movement or usability of the users is unmatched by conventional silicon electronics. There have been reports of the potential application of flexible electrodes on ultrathin substrates (4), flexible sensors that measure biological signals, electrocardiograms, temperature, pressure (5, 6), organic amplifier systems (7), high-sensitivity pressure sensors (8), and ultrathin and imperceptible devices (9, 10).To meas...

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Epidermal photonic devices for quantitative imaging of temperature and thermal transport characteristics of the skin

Cited by 250 publications

References 50 publications

Highly flexible, wearable, and disposable cardiac biosensors for remote and ambulatory monitoring

Highly flexible, wearable, and disposable cardiac biosensors for remote and ambulatory monitoring

Multimodal epidermal devices for hydration monitoring

Ultraflexible, large-area, physiological temperature sensors for multipoint measurements

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