Technology applications

A summary of NASA Technology Utilization programs for the period of 1 December 1971 through 31 May 1972 is presented. An abbreviated description of the overall Technology Utilization Applications Program is provided as a background for the specific applications examples. Subjects discussed are in the broad headings of: (1) cancer, (2) cardiovascular disease, (2) medical instrumentation, (4) urinary system disorders, (5) rehabilitation medicine, (6) air and water pollution, (7) housing and urban construction, (8) fire safety, (9) law enforcement and criminalistics, (10) transportation, and (11) mine safety

Recording, analysis, and interpretation of spreading depolarizations in neurointensive care: Review and recommendations of the COSBID research group.

Spreading depolarizations (SD) are waves of abrupt, near-complete breakdown of neuronal transmembrane ion gradients, are the largest possible pathophysiologic disruption of viable cerebral gray matter, and are a crucial mechanism of lesion development. Spreading depolarizations are increasingly recorded during multimodal neuromonitoring in neurocritical care as a causal biomarker providing a diagnostic summary measure of metabolic failure and excitotoxic injury. Focal ischemia causes spreading depolarization within minutes. Further spreading depolarizations arise for hours to days due to energy supply-demand mismatch in viable tissue. Spreading depolarizations exacerbate neuronal injury through prolonged ionic breakdown and spreading depolarization-related hypoperfusion (spreading ischemia). Local duration of the depolarization indicates local tissue energy status and risk of injury. Regional electrocorticographic monitoring affords even remote detection of injury because spreading depolarizations propagate widely from ischemic or metabolically stressed zones; characteristic patterns, including temporal clusters of spreading depolarizations and persistent depression of spontaneous cortical activity, can be recognized and quantified. Here, we describe the experimental basis for interpreting these patterns and illustrate their translation to human disease. We further provide consensus recommendations for electrocorticographic methods to record, classify, and score spreading depolarizations and associated spreading depressions. These methods offer distinct advantages over other neuromonitoring modalities and allow for future refinement through less invasive and more automated approaches

Multimodal Sensing and Communication with Advanced Components, Circuit topologies, and Biosystem packaging

Monitoring of disease progression by detecting key markers at early stages and providing sufficient intervention to prevent acute and chronic conditions has been a key focus of current wearable and implantable healthcare technologies. When combined with advanced data analytics, these markers can further stratify disease outcomes based on a new set of classifiers for accurate and autonomous predictors. To enable this, the objective of this dissertation is to develop wireless multimodal biosignal monitoring with advanced circuit topologies and thin-film packaging. Specifically, the dissertation seeks to advance implantable electrocorticogram (ECoG) and wearable seismocardiogram (SCG) patches. The proposed strategy consists of three parts: advanced telemetry components for thinner and efficient communication, low-power and low-loss topologies for signal communication, and 3D package integration of a sensor-communication chain for meeting the system targets. The key fundamental advances are demonstrated through in vitro testing using phantom tissue models. This research led to three major scientific and engineering accomplishments. They are: 1) a new class of thin neural ECoG recordings using fully-embedded actives and thin-film passives in a thin flexible package that operates at low power. The recording components are embedded using a chip-first assembly to reduce package dimensions and provide shorter interconnect length for superior electrical performance. Furthermore, embedding components into the substrate can allow for packages with simpler 3D architectures, reducing the number of layers in the circuit design, resulting in thinner packages. 2) development of passive impedance transforming circuits to improve signal sensitivity for the neural recording systems, 3) integration of passive telemetry circuitry with on-skin piezo transducers that led to the first-ever demonstration of a fully-passive wireless seismocardiogram. The dissertation presents: 1) a miniaturized single-layer antenna topology to realize thin substrates for passive telemetry of weak biosignals, 2) skin-compatible PVDF sensors for improving transduction with cardiac mechanical signals, and 3) flexible interconnects with conductive elastomers for embedded-chip thin packages. These developments have resulted in a passive RF backscattering telemetry package with impedance-matched signal interfaces, compliant piezoelectric transducers, and embedded-components, all forming the building blocks towards future health-monitoring needs

Beyond Tissue replacement: The Emerging role of smart implants in healthcare

Smart implants are increasingly used to treat various diseases, track patient status, and restore tissue and organ function. These devices support internal organs, actively stimulate nerves, and monitor essential functions. With continuous monitoring or stimulation, patient observation quality and subsequent treatment can be improved. Additionally, using biodegradable and entirely excreted implant materials eliminates the need for surgical removal, providing a patient-friendly solution. In this review, we classify smart implants and discuss the latest prototypes, materials, and technologies employed in their creation. Our focus lies in exploring medical devices beyond replacing an organ or tissue and incorporating new functionality through sensors and electronic circuits. We also examine the advantages, opportunities, and challenges of creating implantable devices that preserve all critical functions. By presenting an in-depth overview of the current state-of-the-art smart implants, we shed light on persistent issues and limitations while discussing potential avenues for future advancements in materials used for these devices

Non-invasive Monitoring of Brain Temperature during Rapid Selective Brain Cooling by Zero-Heat-Flux Thermometry

Introduction: Selective brain cooling can minimize systemic complications associated with whole body cooling but maximize neuroprotection. Recently, we developed a non-invasive, portable and inexpensive system for selectively cooling the brain rapidly and demonstrated its safety and efficacy in porcine models. However, the widespread application of this technique in the clinical setting requires a reliable, non-invasive and accurate method for measuring local brain temperature so that cooling and rewarming rates can be controlled during targeted temperature management. In this study, we evaluate the ability of a zero-heat-flux SpotOn sensor, mounted on three different locations, to measure brain temperature during selective brain cooling in a pig model. Computed Tomography (CT) was used to determine the position of the SpotOn patches relative to the brain at different placement locations. Methods and Results: Experiments were conducted on two juvenile pigs. Body temperature was measured using a rectal temperature probe while brain temperature with an intraparenchymal thermocouple probe. A SpotOn patch was taped to the pig’s head at three different locations: 1-2 cm posterior (Location #1, n=1), central forehead (Location #2, n=1); and 1-2 cm anterior and lateral to the bregma i.e., above the eye on the forehead (Location #3, n=1). This cooling system was able to rapidly cool the brain temperature to 33.7 ± 0.2°C within 15 minutes, and maintain the brain temperature within 33-34°C for 4-6 hours before slowly rewarming to 34.8 ± 1.1°C from 33.7 ± 0.2°C, while maintaining the core body temperature (as per rectal temperature probe) above 36°C. We measured a mean bias of -1.1°C, -0.2°C and 0.7°C during rapid cooling in induction phase, maintenance and rewarming phase, respectively. Amongst the three locations, location #2 had the highest correlation (R2 = 0.8) between the SpotOn sensor and the thermocouple probe. Conclusions: This SBC method is able to tightly control the rewarming rate within 0.52 ± 0.20°C/h. The SpotOn sensor placed on the center of the forehead provides a good measurement of brain temperature in comparison to the invasive needle probe

VAD in failing Fontan: simulation of ventricular, cavo-pulmonary and biventricular assistance in systolic/diastolic ventricular dysfunction and in pulmonary vascular resistance increase.

Aim: Due to the lack of donors, VADs could be an alternative to heart transplantation for Failing Fontan patients (PTs). Considering the complex physiopathology and the type of VAD connection, a numerical model (NM) could be useful to support clinical decisions. The aim of this work is to test a NM simulating the VADs effects on failing Fontan for systolic dysfunction (SD), diastolic dysfunction (DD) and pulmonary vascular resistance increase (PRI). Methods: Data of 10 Fontan PTs were used to simulate the PTs baseline using a dedicated NM. Then, for each PTs a SD, a DD and a PRI were simulated. Finally, for each PT and for each pathology, the VADs implantation was simulated. Results: NM can well reproduce PTs baseline. In the case of SD, LVAD increases the cardiac output (CO) (35%) and the arterial systemic pressure (ASP) (25%). With cavo-pulmonary assistance (RVAD) a decrease of inferior vena cava pressure (IVCP) (39%) was observed with 34% increase of CO. With the BIVAD an increase of ASP (29%) and CO (37%) was observed. In the case of DD, the LVAD increases CO (42%), the RVAD decreases the IVCP. In the case of PRI, the highest CO (50%) and ASP (28%) increase is obtained with an RVAD together with the highest decrease of IVCP (53%). Conclusions: The use of NM could be helpful in this innovative field to evaluate the VADs implantation effects on specific PT to support PT and VAD selection

Inductively Powered Implantable System with Far-field Data Transmitter for an Intracranial Pressure Monitoring Application: Design and Performance Validation

Monitoring of the intracranial pressure (ICP) is an essential activity for many brain diseases and injuries. For an adult, ICP value is between 7 mmHg to 15 mmHg . However, for a critically ill patient, the ICP should be maintained below 20 mmHg. Therefore, continuous monitoring of ICP is a life-saving activity. Several invasive and non-invasive methods have been proposed for monitoring of the ICP. However, invasive methods cannot be used for continuous monitoring of the ICP due to the risk of infection. Moreover, non-invasive methods lack in accuracy.Therefore, many researchers reported battery-powered or fully passive implantable systems. However, a battery-powered implant has limited life and large size. On the other hand, in a fully passive implant the readout distance is relatively small in comparison with a battery-powered implant due to its zero-power operation.In contrast, this work presents the development of an inductively powered implantable system equipped with a data transmission unit for an ICP monitoring application. The developed system has three main parts: an implant or in-body unit, an on-body unit and an off-body unit. The on-body unit powers the implant through inductive near-field link. After the activation, the implant, consists of a piezoresistive pressure sensor and a data transmission unit, transmits the pressure signal at the industrial, scientific, and medical radio (ISM) band of 2.45 GHz. The off-body unit receives the transmitted signal from the implant and estimates the pressure value.The simulation and the measurement results of both near-filed and far-field links are presented. After the development of the system, the pressue readout measurement results have been presented in the air, water and in a setting mimicking the human head dielectric properties. For biocompatibility, the implant is coated with biocompatible adhesive silicone. The effect of coating on both wireless links has also been studied.Finally, this work also presents the effect of misalignment between the inductively coupled antennas on the pressure readout accuracy of the developed ICP monitoring system and discusses the solution to overcome this impact. The thesis also presents the response of the developed ICP monitoring system with the change in the temperature

Implantable Antennas for Biomedical Purposes: State-of-the-Art, Challenges, and Future Directions

This article provides a comprehensive review of implantable antennas in the context of their application within the biomedical field. Through a systematic exploration of cutting-edge developments and associated challenges, a thorough understanding of antenna design, performance considerations, and safety implications is obtained. The investigation thoroughly examines diverse antenna types, including planar, microstrip, fractal-geometry, and others, elucidating the design considerations that govern their suitability for a wide array of implantable medical devices (IMDs). Substrate and material choices are critical factors influencing antenna efficiency and biocompatibility. The utilization of available frequency bands is evaluated, highlighting the inherent tradeoffs that dictate their applicability in biomedical applications. Additionally, the promising domain of rectenna technology is explored for its potential in sustainable energy harvesting. The discourse on miniaturization techniques underscores their pivotal role in enabling the seamless integration of antennas within intricate implant structures. Safety aspects are paramount, encompassing metrics such as specific absorption range (SAR), maximum permissible exposure (MPE) limits, and thresholds for localized temperature changes. The intricate interplay between human body effects and antenna performance is briefly elaborated. Methodologies for thorough evaluation, spanning computer simulations, as well as experiments in in vivo and in vitro scenarios, are discussed for their pivotal role in iteratively refining antenna functionality

Transcranial optical monitoring for detecting intracranial pressure alterations in children with benign external hydrocephalus: a proof-of-concept study

Hydrocephalus; Optical techniques; PathophysiologyHidrocefalia; Técnicas ópticas; FisiopatologíaHidrocefàlia; Tècniques òptiques; FisiopatologiaSignificance Benign external hydrocephalus (BEH) is considered a self-limiting pathology with a good prognosis. However, some children present a pathological intracranial pressure (ICP) characterized by quantitative and qualitative alterations (the so-called B-waves) that can lead to neurological sequelae. Aim Our purpose was to evaluate whether there were cerebral hemodynamic changes associated with ICP B-waves that could be evaluated with noninvasive neuromonitoring. Approach We recruited eleven patients (median age 16 months, range 7 to 55 months) with BEH and an unfavorable evolution requiring ICP monitoring. Bedside, nocturnal monitoring using near-infrared time-resolved and diffuse correlation spectroscopies synchronized to the clinical monitoring was performed. Results By focusing on the timing of different ICP patterns that were identified manually by clinicians, we detected significant tissue oxygen saturation (StO2) changes (p = 0.002) and blood flow index (BFI) variability (p = 0.005) between regular and high-amplitude B-wave patterns. A blinded analysis looking for analogs of ICP patterns in BFI time traces achieved 90% sensitivity in identifying B-waves and 76% specificity in detecting the regular patterns. Conclusions We revealed the presence of StO2 and BFI variations—detectable with optical techniques—during ICP B-waves in BEH children. Finally, the feasibility of detecting ICP B-waves in hemodynamic time traces obtained noninvasively was shown.This work was realized with the support of the Department of Cirugía and Ciencias Morfológicas of the Universitat Autònoma de Barcelona. The work was supported by the European Union’s Horizon 2020 Research and Innovation Program under the Marie Sklodowska-Curie (Grant No. 675332) (BitMap: brain injury and trauma monitoring using advanced photonics) and the European Union’s Horizon 2020 Research and Innovation Program [Grant No. 101017113 (TinyBrains) and Grant No. 101016087 (VASCOVID)]; Fondo de Investigación Sanitaria (Instituto de Salud Carlos III) (Grant No. PI18/00468); Fundació CELLEX Barcelona, Fundació Mir Puig, Agencia Estatal de Investigación (PHOTOMETABO, Grant No. PID2019106481RBC31); the “Severo Ochoa” Program for Centers of Excelence in R&D (Grant No. CEX2019-000910-S); the Obra social “La Caixa” Foundation (LlumMedBcn), Generalitat de Catalunya (CERCA, AGAUR-2017-SGR-1380, RIS3CAT-001-P-001682 CECH), FEDER EC and LASERLAB EUROPE V (EC H2020 No. 871124); KidsBrainIT (ERANET NEURON); Fundació La Marató de TV3 (Grant Nos. 201724.31 and 201709.31)