Dependence of Skin-Electrode Contact Impedance on Material and Skin Hydration.

Dry electrodes offer an accessible continuous acquisition of biopotential signals as part of current in-home monitoring systems but often face challenges of high-contact impedance that results in poor signal quality. The performance of dry electrodes could be affected by electrode material and skin hydration. Herein, we investigate these dependencies using a circuit skin-electrode interface model, varying material and hydration in controlled benchtop experiments on a biomimetic skin phantom simulating dry and hydrated skin.

A miniaturized 3D printed pressure regulator (µPR) for microfluidic cell culture applications.

Well-defined fluid flows are the hallmark feature of microfluidic culture systems and enable precise control over biophysical and biochemical cues at the cellular scale. Microfluidic flow control is generally achieved using displacement-based (e.g.

A biomimetic skin phantom for characterizing wearable electrodes in the low-frequency regime.

Advances in the integration of wearable devices in our daily life have led to the development of new electrode designs for biopotential monitoring. Historically, the development and testing of wearable electrodes for the acquisition of biopotential signals has been empirical, relying on experiments on human volunteers. However, the lack of explicit control on human variables, the intra-, and inter-subject variability complicates the understanding of the performance of these wearable electrodes.

A review of peristaltic micropumps.

This report presents a review of progress on peristaltic micropumps since their emergence, which have been widely used in many research fields from biology to aeronautics. This paper summarizes different techniques that have been used to mimic this elegant physiological transport mechanism that is commonly found in nature. The analysis provides definitions of peristaltic micropumps and their different features, distinguishing them from other mechanical micropumps.

A Wirelessly Controlled Scalable 3D-Printed Microsystem for Drug Delivery.

Here we present a 3D-printed, wirelessly controlled microsystem for drug delivery, comprising a refillable microreservoir and a phase-change peristaltic micropump. The micropump structure was inkjet-printed on the back of a printed circuit board around a catheter microtubing. The enclosure of the microsystem was fabricated using stereolithography 3D printing, with an embedded microreservoir structure and integrated micropump.

Microengineered 3D Collagen Gels with Independently Tunable Fiber Anisotropy and Directionality.

Cellular processes, including differentiation, proliferation, and migration, have been linked to the alignment (anisotropy) and orientation (directionality) of collagen fibers in the native extracellular matrix (ECM). Given the critical role that biophysical cell-matrix interactions play in regulating biological functions, several microfluidic-based methods have been used to establish 3D collagen gels with defined fiber properties; these gels have helped to establish quantitative relationships between structural ECM cues and observed cell responses. Although existing microfluidic fabrication methods provide excellent definition over collagen fiber anisotropy, they have not demonstrated the independent control over fiber anisotropy and directionality necessary to replicate collagen architecture.

Deep Volumetric Segmentation of Murine Cochlear Compartments from Micro-Computed Tomography Images.

Local drug delivery to the inner ear via micropump implants has the potential to be much more effective than oral drug delivery for treating patients with sensorineural hearing loss and to protect hearing from ototoxic insult due to noise exposure or cancer treatments. Designing micropumps to deliver appropriate concentrations of drugs to the necessary cochlear compartments is of paramount importance; however, directly measuring local drug concentrations over time throughout the cochlea is not possible. Recent approaches for indirectly quantifying local drug concentrations in animal models capture a series of magnetic resonance (MR) or micro computed tomography (µCT) images before and after infusion of a contrast agent into the cochlea.

Microtechnologies for inner ear drug delivery.

Purpose Of Review: Treatment of auditory dysfunction is dependent on inner ear drug delivery, with microtechnologies playing an increasingly important role in cochlear access and pharmacokinetic profile control. This review examines recent developments in the field for clinical and animal research environments.

Recent Findings: Micropump technologies are being developed for dynamic control of flow rates with refillable reservoirs enabling timed delivery of multiple agents for protection or regeneration therapies.

A 3D-Printed Modular Microreservoir for Drug Delivery.

Reservoir-based drug delivery microsystems have enabled novel and effective drug delivery concepts in recent decades. These systems typically comprise integrated storing and pumping components. Here we present a stand-alone, modular, thin, scalable, and refillable microreservoir platform as a storing component of these microsystems for implantable and transdermal drug delivery.

Cochlear pharmacokinetics - Micro-computed tomography and learning-prediction modeling for transport parameter determination.

Inner ear disorders such as sensorineural deafness and genetic diseases may one day be treated with local drug delivery to the inner ear. Current pharmacokinetic models have been based on invasive methods to measure drug concentrations, limiting them in spatial resolution, and restricting the research to larger rodents. We developed an intracochlear pharmacokinetic model based on an imaging, learning-prediction (LP) paradigm for learning transport parameters in the murine cochlea.

Magnetic Field Patterning of Nickel Nanowire Film Realized by Printed Precursor Inks.

This paper demonstrates an easily prepared novel material and approach to producing aligned nickel (Ni) nanowires having unique and customizable structures on a variety of substrates for electronic and magnetic applications. This is a new approach to producing printed metallic Ni structures from precursor materials, and it provides a novel technique for nanowire formation during reduction. This homogeneous solution can be printed in ambient conditions, and it forms aligned elemental Ni nanowires over large areas upon heating in the presence of a magnetic field.

A nanoliter resolution implantable micropump for murine inner ear drug delivery.

Advances in protective and restorative biotherapies have created new opportunities to use site-directed, programmable drug delivery systems to treat auditory and vestibular disorders. Successful therapy development that leverages the transgenic, knock-in, and knock-out variants of mouse models of human disease requires advanced microsystems specifically designed to function with nanoliter precision and with system volumes suitable for implantation. Here we present results for a novel biocompatible, implantable, scalable, and wirelessly controlled peristaltic micropump.

In-Home Cardiovascular Monitoring System for Heart Failure: Comparative Study.

Background: There is a pressing need to reduce the hospitalization rate of heart failure patients to limit rising health care costs and improve outcomes. Tracking physiologic changes to detect early deterioration in the home has the potential to reduce hospitalization rates through early intervention. However, classical approaches to in-home monitoring have had limited success, with patient adherence cited as a major barrier.

Inkjet Printed Polyethylene Glycol as a Fugitive Ink for the Fabrication of Flexible Microfluidic Systems.

This paper demonstrates a novel and simple processing technique for the realization of scalable and flexible microfluidic microsystems by inkjet-printing polyethylene-glycol (PEG) as a sacrificial template, followed by embedding in a structural layer (e.g. soft elastomers).

Nontraditional Electrocardiogram and Algorithms for Inconspicuous In-Home Monitoring: Comparative Study.

Background: Wearable and connected in-home medical devices are typically utilized in uncontrolled environments and often measure physiologic signals at suboptimal locations. Motion artifacts and reduced signal-to-noise ratio, compared with clinical grade equipment, results in a highly variable signal quality that can change significantly from moment to moment. The use of signal quality classification algorithms and robust feature delineation algorithms designed to achieve high accuracy on poor quality physiologic signals can prove beneficial in addressing concerns associated with measurement accuracy, confidence, and clinical validity.

Early uneven ear input induces long-lasting differences in left-right motor function.

How asymmetries in motor behavior become established normally or atypically in mammals remains unclear. An established model for motor asymmetry that is conserved across mammals can be obtained by experimentally inducing asymmetric striatal dopamine activity. However, the factors that can cause motor asymmetries in the absence of experimental manipulations to the brain remain unknown.

A physics based approach to the pulse wave velocity prediction in compliant arterial segments.

Pulse wave velocity (PWV) quantification commonly serves as a highly robust prognostic parameter being used in a preventative cardiovascular therapy. Being dependent on arterial elastance, it can serve as a marker of cardiovascular risk. Since it is influenced by a blood pressure (BP), the pertaining theory can lay the foundation in developing a technique for noninvasive blood pressure measurement.

Improved Blood Pressure Prediction Using Systolic Flow Correction of Pulse Wave Velocity.

Hypertension is a significant worldwide health issue. Continuous blood pressure monitoring is important for early detection of hypertension, and for improving treatment efficacy and compliance. Pulse wave velocity (PWV) has the potential to allow for a continuous blood pressure monitoring device; however published studies demonstrate significant variability in this correlation.

Towards an Implantable, Low Flow Micropump That Uses No Power in the Blocked-Flow State.

Low flow rate micropumps play an increasingly important role in drug therapy research. Infusions to small biological structures and lab-on-a-chip applications require ultra-low flow rates and will benefit from the ability to expend no power in the blocked-flow state. Here we present a planar micropump based on gallium phase-change actuation that leverages expansion during solidification to occlude the flow channel in the off-power state.

Pulse Wave Velocity Prediction and Compliance Assessment in Elastic Arterial Segments.

Pressure wave velocity (PWV) is commonly used as a clinical marker of vascular elasticity. Recent studies have increased clinical interest in also analyzing the impact of heart rate, blood pressure, and left ventricular ejection time on PWV. In this article we focus on the development of a theoretical one-dimensional model and validation via direct measurement of the impact of ejection time and peak pressure on PWV using an in vitro hemodynamic simulator.

Scoring consensus of multiple ECG annotators by optimal sequence alignment.

Development of ECG delineation algorithms has been an area of intense research in the field of computational cardiology for the past few decades. However, devising evaluation techniques for scoring and/or merging the results of such algorithms, both in the presence or absence of gold standards, still remains as a challenge. This is mainly due to existence of missed or erroneous determination of fiducial points in the results of different annotation algorithms.

The electric field strength in orifice-like nanopores of ultrathin membranes.

Here we show that the electric field inside an ultrathin membrane is weaker than conventional theory would predict, and that the reduced field is predictive of measured electroosmotic flow rates. Our theoretical analysis shows that the electric field inside a charged nanopore is affected by end effects and dependent on the Dukhin number Du when the pore length-to-diameter aspect ratio λ is less than 80 for Du ≪ 1 or 300 for Du ≫ 1. The electric field follows an unconventional scaling law; it no longer scales uniformly with the thickness of membrane, but with the local value of λ for each nanopore.

The focal index as a singular metric for beamforming effectiveness.

Hearing-impaired individuals frequently cite intelligibility problems in multi-talker environments. Microphone arrays performing time-delay beamforming address conditions of poor signal-to-noise ratio by spatially filtering incoming sound. Existing beam pattern metrics including peak side lobe level, integrated side lobe level, beamwidth, and planar directivity index fail to quantitatively capture all elements essential for improving speech intelligibility in multi-talker situations.

Fetal QRS extraction from abdominal recordings via model-based signal processing and intelligent signal merging.

Noninvasive fetal ECG (fECG) monitoring has potential applications in diagnosing congenital heart diseases in a timely manner and assisting clinicians to make more appropriate decisions during labor. However, despite advances in signal processing and machine learning techniques, the analysis of fECG signals has still remained in its preliminary stages. In this work, we describe an algorithm to automatically locate QRS complexes in noninvasive fECG signals obtained from a set of four electrodes placed on the mother's abdomen.

Round window membrane intracochlear drug delivery enhanced by induced advection.

Delivery of therapeutic compounds to the inner ear via absorption through the round window membrane (RWM) has advantages over direct intracochlear infusions; specifically, minimizing impact upon functional hearing measures. However, previous reports show that significant basal-to-apical concentration gradients occur, with the potential to impact treatment efficacy. Here we present a new approach to inner ear drug delivery with induced advection aiding distribution of compounds throughout the inner ear in the murine cochlea.