Search

Wearable devices for continuous monitoring of arterial pulse waves have the potential to improve the diagnosis, prognosis, and management of cardiovascular diseases. These pulse wave signals are often affected by the contact pressure between the wearable device and the skin, limiting the accuracy and reliability of hemodynamic parameter quantification. Here, a continuous hemodynamic monitoring device that enables the simultaneous recording of dual‐channel bioimpedance and quantification of pulse wave velocity (PWV) and blood pressure (BP) is reported. The investigations demonstrate the effect of contact pressure on bioimpedance and PWV. The pulsatile bioimpedance magnitude reached its maximum when the contact pressure approximated the mean arterial pressure of the subject. PWV is employed to continuously quantify BP while maintaining comfortable contact pressure for prolonged wear. The mean absolute error and standard deviation of the error compared to the reference value are determined to be 0.1 ± 3.3 mmHg for systolic BP, 1.3 ± 3.7 mmHg for diastolic BP, and −0.4 ± 3.0 mmHg for mean arterial pressure when measurements are conducted in the lying down position. This research demonstrates the potential of wearable dual‐bioimpedance sensors with contact pressure guidance for reliable and continuous hemodynamic monitoring. [ABSTRACT FROM AUTHOR]

Continuous monitoring of arterial blood pressure is clinically important for diagnosing and managing cardiovascular diseases. Soft electronic devices with skin‐like properties show promise in various applications, including the human‐machine interface, the Internet of Things, and health monitoring. Herein, the use of add‐on soft electronic interfaces addresses the connection challenges between soft electrodes and rigid data acquisition circuitry for bioimpedance monitoring of cardiac signals, including heart rate and cuffless blood pressure is reported. Nanocomposite films in add‐on electrodes provide robust electrical and mechanical contact with the skin and the rigid circuitry. Bioimpedance sensors composed of add‐on electrodes offer continuous blood pressure monitoring with high accuracy. Specifically, the bioimpedance collected with add‐on nanocomposite electrodes shows a signal‐to‐noise ratio of 37.0 dB, higher than the ratio of 25.9 dB obtained with standard silver/silver chloride (Ag/AgCl) gel electrodes. Although the sample set is low, the continuously measured systolic and diastolic blood pressure offer accuracy of −2.0 ± 6.3 mmHg and −4.3 ± 3.9 mmHg, respectively, confirming the grade A performance based on the IEEE standard. These results show promise in bioimpedance measurements with add‐on soft electrodes for cuffless blood pressure monitoring. [ABSTRACT FROM AUTHOR]

Electronic skin (E‐skin) that can mimic the flexibility and stretchability of human skin with sensing capabilities, holds transformative potential in robotics, wearable technology, and healthcare. However, developing E‐skin poses significant challenges such as creating durable materials with skin‐like flexibility, integrating biosensing abilities, and using advanced fabrication techniques for wearable or implantable applications. To overcome these hurdles, a 3D‐printed electronic skin utilizing a novel class of nanoengineered hydrogels with tunable electronic and thermal biosensing capabilities is fabricated. This methodology takes advantage of the shear–thinning behavior in hydrogel precursors, allowing to construct intricate 2D and 3D electronic structures. The elasticity of skin using triple crosslinking in a robust fungal exopolysaccharide, and pullulan is simulated, while defect‐rich 2D molybdenum disulfide (MoS2) nanoassemblies ensure high electrical conductivity. The addition of polydopamine nanoparticles enhances adhesion to wet tissue. The hydrogel exhibits outstanding flexibility, stretchability, adhesion, moldability, and electrical conductivity. A distinctive feature of this technology is the precise detection of dynamic changes in strain, pressure, and temperature. As a human motion tracker, phonatory‐recognition platform, flexible touchpad, and thermometer, this technology represents a breakthrough in flexible wearable skins and holds transformative potential for the future of robotics and human‐machine interfaces. [ABSTRACT FROM AUTHOR]

Core body temperature (CBT) is a vital parameter that provides insight into individuals' overall health. However, existing methods to monitor CBT are mainly invasive and limited to applications in operating rooms. This work reports a soft wearable thermal device with low power operation to accurately monitor the core temperature and overcome these limitations. The thermal device comprises multiple temperature sensors separated with insulating materials of different thermal conductivities. The design provides a well‐defined thermal gradient to characterize the heat flux across the device. Thermal simulation of the devices with finite element analysis provides guidelines on the device design. Experimental studies involving tissue phantom and human subjects characterize and validate the device performance. A machine learning approach can account for heterogeneous, hard‐to‐measure parameters among individuals such as tissue thermal conductivity and heat generation rate. The machine learning algorithms can be trained to accurately quantify the core temperature in human subjects using the zero‐heat‐flux device measured temperature as a reference. The results show that the mean core temperature difference between the zero‐heat‐flux and the devices is 0.01 °C with 95% limits of agreement in the range of −0.08 °C and 0.1 °C. [ABSTRACT FROM AUTHOR]

This article, titled "3D Printed Electronic Skin for Strain, Pressure and Temperature Sensing," discusses the development of 3D-printed electronic skin that mimics human sensitivity. The researchers, led by Akhilesh K. Gaharwar, demonstrate that the nanoengineering of this electronic skin allows for multifunctional capabilities, such as motion, touch, and temperature detection. This advancement in wearable technology and human-machine interfaces has the potential to pave new paths in robotics and personal devices. The article provides valuable insights into the potential applications of this technology. [Extracted from the article]

Concentrator photovoltaic (CPV) systems, where incident direct solar radiation is tightly concentrated onto high-efficiency multi-junction solar cells by geometric optical elements, exhibit the highest efficiencies in converting the sun’s energy into electric power. Their energy conversion efficiencies are greatly limited, however, due to Fresnel reflection losses occurring at three air/optics interfaces in the most sophisticated dual-stage CPV platforms. This paper describes a facile one-step wet-etching process to create a nanoporous surface with a graded-index profile on both flat and curved glasses, with capabilities of achieving ~99% average transmission efficiency in a wide wavelength range from 380 nm to 1.3 µm and for a wide range of incident angles up to ±40° regardless of the polarization state of incident sunlight. The simplicity of the etching process remarkably increases their versatility in various optical elements that require unconventional form factors such as Fresnel lenses and microlens arrays, and/or demanding curvatures along with much reduced dimensions such as ball lenses. Etched glass surfaces on two-stage optical concentrating systems yield enhancements in total optical transmission efficiencies by 13.8% and in the photocurrent by 14.3%, as experimentally determined by measurements on microscale triple-junction solar cells. The presented strategy can be widely adapted in a variety of applications such as image sensors, display systems, and other optoelectronic devices. [ABSTRACT FROM AUTHOR]