Rapid advances in semiconductor nanomaterials, techniques for their assembly, and strategies for incorporation into functional systems now enable sophisticated modes of functionality and ...corresponding use scenarios in electronics that cannot be addressed with conventional, wafer-based technologies. This short review highlights enabling developments in the synthesis of one- and two-dimensional semiconductor nanomaterials (that is, NWs and nanomembranes), their manipulation and use in various device components together with concepts in mechanics that allow integration onto flexible plastic foils and stretchable rubber sheets. Examples of systems that combine with or are inspired by biology illustrate the current state-of-the-art in this fast-moving field.
The mammalian inner ear separates sounds by their frequency content, and this separation underlies important properties of human hearing, including our ability to understand speech in noisy ...environments. Studies of genetic disorders of hearing have demonstrated a link between frequency selectivity and wave properties of the tectorial membrane (TM). To understand these wave properties better, we developed chemical manipulations that systematically and reversibly alter TM stiffness and viscosity. Using microfabricated shear probes, we show that (i) reducing pH reduces TM stiffness with little change in TM viscosity and (ii) adding PEG increases TM viscosity with little change in TM stiffness. By applying these manipulations in measurements of TM waves, we show that TM wave speed is determined primarily by stiffness at low frequencies and by viscosity at high frequencies. Both TM viscosity and stiffness affect the longitudinal spread of mechanical excitation through the TM over a broad range of frequencies. Increasing TM viscosity or decreasing stiffness reduces longitudinal spread of mechanical excitation, thereby coupling a smaller range of best frequencies and sharpening tuning. In contrast, increasing viscous loss or decreasing stiffness would tend to broaden tuning in resonance-based TMmodels. Thus, TM wave and resonance mechanisms are fundamentally different in the way they control frequency selectivity.
Biomimetic miniaturized suction cups (mSCs) are designed for the patient friendly, dry adhesives of smart medical skin. Both strong van der Waals force and induced negative pressure by the ultrasoft ...mSCs facilitate tight skin coupling without discomfort or irritations, improve sensitivities of the embedded stretchable electronics for continuous vital sign monitoring, and enable multiple drug reloading without loss of the adhesion.
Curved surfaces, complex geometries, and time-dynamic deformations of the heart create challenges in establishing intimate, nonconstraining interfaces between cardiac structures and medical devices ...or surgical tools, particularly over large areas. We constructed large area designs for diagnostic and therapeutic stretchable sensor and actuator webs that conformally wrap the epicardium, establishing robust contact without sutures, mechanical fixtures, tapes, or surgical adhesives. These multifunctional web devices exploit open, mesh layouts and mount on thin, bio-resorbable sheets of silk to facilitate handling in a way that yields, after dissolution, exceptionally low mechanical moduli and thicknesses. In vivo studies in rabbit and pig animal models demonstrate the effectiveness of these device webs for measuring and spatially mapping temperature, electrophysiological signals, strain, and physical contact in sheet and balloon-based systems that also have the potential to deliver energy to perform localized tissue ablation.
Sound-evoked vibrations transmitted into the mammalian cochlea produce traveling waves that provide the mechanical tuning necessary for spectral decomposition of sound. These traveling waves of ...motion that have been observed to propagate longitudinally along the basilar membrane (BM) ultimately stimulate the mechano-sensory receptors. The tectorial membrane (TM) plays a key role in this process, but its mechanical function remains unclear. Here we show that the TM supports traveling waves that are an intrinsic feature of its visco-elastic structure. Radial forces applied at audio frequencies (2-20 kHz) to isolated TM segments generate longitudinally propagating waves on the TM with velocities similar to those of the BM traveling wave near its best frequency place. We compute the dynamic shear storage modulus and shear viscosity of the TM from the propagation velocity of the waves and show that segments of the TM from the basal turn are stiffer than apical segments are. Analysis of loading effects of hair bundle stiffness, the limbal attachment of the TM, and viscous damping in the subtectorial space suggests that TM traveling waves can occur in vivo. Our results show the presence of a traveling wave mechanism through the TM that can functionally couple a significant longitudinal extent of the cochlea and may interact with the BM wave to greatly enhance cochlear sensitivity and tuning.
Excessive ultraviolet (UV) radiation induces acute and chronic effects on the skin, eye and immune system. Personalized monitoring of UV radiation is thus paramount to measure the extent of personal ...sun exposure, which could vary with environment, lifestyle, and sunscreen use. Here, we demonstrate an ultralow modulus, stretchable, skin-mounted UV patch that measures personal UV doses. The patch contains functional layers of ultrathin stretchable electronics and a photosensitive patterned dye that reacts to UV radiation. Color changes in the photosensitive dyes correspond to UV radiation intensity and are analyzed with a smartphone camera. A software application has feature recognition, lighting condition correction, and quantification algorithms that detect and quantify changes in color. These color changes are then correlated with corresponding shifts in UV dose, and compared to existing UV dose risk levels. The soft mechanics of the UV patch allow for multi-day wear in the presence of sunscreen and water. Two evaluation studies serve to demonstrate the utility of the UV patch during daily activities with and without sunscreen application.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Gait and balance impairments are linked with reduced mobility and increased risk of falling. Wearable sensing technologies, such as inertial measurement units (IMUs), may augment clinical assessments ...by providing continuous, high-resolution data. This study tested and validated the utility of a single IMU to quantify gait and balance features during routine clinical outcome tests, and evaluated changes in sensor-derived measurements with age, sex, height, and weight. Age-ranged, healthy individuals (N = 49, 20-70 years) wore a lower back IMU during the 10 m walk test (10MWT), Timed Up and Go (TUG), and Berg Balance Scale (BBS). Spatiotemporal gait parameters computed from the sensor data were validated against gold standard measures, demonstrating excellent agreement for stance time, step time, gait velocity, and step count (intraclass correlation (ICC) > 0.90). There was good agreement for swing time (ICC = 0.78) and moderate agreement for step length (ICC = 0.68). A total of 184 features were calculated from the acceleration and angular velocity signals across these tests, 36 of which had significant correlations with age. This approach was also demonstrated for an individual with stroke, providing higher resolution information about balance, gait, and mobility than the clinical test scores alone. Leveraging mobility data from wireless, wearable sensors can help clinicians and patients more objectively pinpoint impairments, track progression, and set personalized goals during and after rehabilitation.
A class of ferromagnetic, folded, soft composite material for skin‐interfaced electrodes with releasable interfaces to stretchable, wireless electronic measurement systems is introduced. These ...electrodes establish intimate, adhesive contacts to the skin, in dimensionally stable formats compatible with multiple days of continuous operation, with several key advantages over conventional hydrogel‐based alternatives. The reported studies focus on aspects ranging from ferromagnetic and mechanical behavior of the materials systems, to electrical properties associated with their skin interface, to system‐level integration for advanced electrophysiological monitoring applications. The work combines experimental measurement and theoretical modeling to establish the key design considerations. These concepts have potential uses across a diverse set of skin‐integrated electronic technologies.
A ferromagnetic, folded, soft‐electrode composite material with long‐term usage and system‐level integration in electrophysiological monitoring is introduced. Systematic investigations including the ferromagnetism behaviors, mechanical properties, electrical interfaces to the skin, and their materials aspects are carried out. The electrodes provide advantages in non‐irritating contacts to the skin, dimensionally stable geometries, and robust bonding to the skin and the measurement platforms.
Advanced capabilities in noninvasive, in situ monitoring of parameters related to sweat serve as the basis for obtaining real‐time insights into human physiological state, health, and performance. ...Although recently reported classes of soft, skin‐interfaced microfluidic systems support powerful functions in this context, most are designed as single‐use disposables. As a result, associated waste streams have the potential to create adverse environmental impacts. Here, we introduce materials and fabrication techniques that bypass these concerns through biodegradable microfluidic systems with a full range of features, including measurement of sweat rate and total loss, and colorimetric analysis of biomarkers. The key components fully degrade through the enzymatic action of microorganisms in natural soil environments, or in industrial compost facilities, to yield end products with beneficial uses as fertilizers and species to improve soil health. Detailed characterization of the constituent materials, the fabrication procedures, the assembly processes, and the completed devices reveal a set of essential performance parameters that are comparable to, or even better than, those of non‐degradable counterparts. Human subject studies illustrate the ability of these devices to acquire accurate measurements of sweat loss, sweat rate, pH, and chloride concentration during physical activities and thermal exposures.
Soft, skin‐interfaced microfluidic systems exploit biodegradable thermoplastic copolyester elastomers for the microfluidic layers, cellulose films and pressure sensitive adhesives as sealing layers, and carefully selected chemical reagents as colorimetric assays for monitoring sweat loss, sweat rate, pH, and chloride concentration. The resulting platforms can fully degrade in natural soil or composting facilities to organic compounds that can act as plant nutrients, thereby eliminating environmental stresses from discarded devices.
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