Continuous biosignal acquisition beyond the limit of epidermal turnover.

Acquisition of biosignals is particularly valuable if uninterrupted data streams are collected over weeks or months without gaps. This is currently only possible with devices that feature long battery life and interfaces such as belts and straps that result in substantial limitations for signal fidelity, sensor location, wear comfort and user retention. State of the art patch-type wearables provide advanced sensing modalities, however, they require adhesives that need to frequently be replaced because of epidermal turnover and pose related limits for chronic operation.

Wearable continuous diffusion-based skin gas analysis.

Biophysical signals such as motion and optically acquired hemodynamics represent foundational sensing modalities for wearables. Expansion of this toolset is vital for the progression of digital medicine. Current efforts utilize biofluids such as sweat and interstitial fluid with primarily adhesively mounted sensors that are fundamentally limited by epidermal turnover.

Continuous operation of battery-free implants enables advanced fracture recovery monitoring.

Substantial hurdles in achieving a digitally connected body with seamless, chronic, high-fidelity organ interfaces include challenges of sourcing energy and ensuring reliable connectivity. Operation is currently limited by batteries that occupy large volumes. Wireless, battery-free operation is therefore paramount, requiring a system-level solution that enables seamless connection of wearable and implantable devices.

Chronic, Battery-Free, Fully Implantable Multimodal Spinal Cord Stimulator for Pain Modulation in Small Animal Models.

Spinal cord stimulation (SCS) for chronic pain management is an invasive therapy involving surgical implantation of electrodes into spinal epidural space. While the clinical value and mechanistic action of the therapy is debated considerably in recent years, preclinical chronic studies employing rodent models can provide invaluable insights regarding the balance between efficacy and complications as well as mechanistic understanding of SCS therapy. However, current rodent compatible devices require tethered power delivery or bulky batteries, severely limiting the ability to probe long-term efficacy of SCS therapy.

Biosymbiotic haptic feedback - Sustained long term human machine interfaces.

Haptic technology permeates diverse fields and is receiving renewed attention for VR and AR applications. Advances in flexible electronics, facilitate the integration of haptic technologies into soft wearable systems, however, because of small footprint requirements face challenges of operational time requiring either large batteries, wired connections or frequent recharge, restricting the utility of haptic devices to short-duration tasks or low duty cycles, prohibiting continuously assisting applications. Currently many chronic applications are not investigated because of this technological gap.

Monolithically Defined Wireless Fully Implantable Nervous System Interfaces.

Evolution of implantable neural interfaces is critical in addressing the challenges in understanding the fundamental working principles and therapeutic applications for central and peripheral nervous systems. Traditional approaches utilizing hermetically sealed, rigid electronics and detached electrodes face challenges in power supply, encapsulation, channel count, dispersed application location, and modality. Employing thin-film, wirelessly powered devices is promising to expand capabilities.

Wireless Battery-free and Fully Implantable Organ Interfaces.

Advances in soft materials, miniaturized electronics, sensors, stimulators, radios, and battery-free power supplies are resulting in a new generation of fully implantable organ interfaces that leverage volumetric reduction and soft mechanics by eliminating electrochemical power storage. This device class offers the ability to provide high-fidelity readouts of physiological processes, enables stimulation, and allows control over organs to realize new therapeutic and diagnostic paradigms. Driven by seamless integration with connected infrastructure, these devices enable personalized digital medicine.

Biosymbiotic platform for chronic long-range monitoring of biosignals in limited resource settings.

Remote patient monitoring is a critical component of digital medicine, and the COVID-19 pandemic has further highlighted its importance. Wearable sensors aimed at noninvasive extraction and transmission of high-fidelity physiological data provide an avenue toward at-home diagnostics and therapeutics; however, the infrastructure requirements for such devices limit their use to areas with well-established connectivity. This accentuates the socioeconomic and geopolitical gap in digital health technology and points toward a need to provide access in areas that have limited resources.

Fully implanted battery-free high power platform for chronic spinal and muscular functional electrical stimulation.

Electrical stimulation of the neuromuscular system holds promise for both scientific and therapeutic biomedical applications. Supplying and maintaining the power necessary to drive stimulation chronically is a fundamental challenge in these applications, especially when high voltages or currents are required. Wireless systems, in which energy is supplied through near field power transfer, could eliminate complications caused by battery packs or external connections, but currently do not provide the harvested power and voltages required for applications such as muscle stimulation.

Context-aware electromagnetic design for continuously wearable biosymbiotic devices.

Imperceptible wireless wearable devices are critical to advance digital medicine with the goal to capture clinical-grade biosignals continuously. Design of these systems is complex because of unique interdependent electromagnetic, mechanic and system level considerations that directly influence performance. Typically, approaches consider body location, related mechanical loads, and desired sensing capabilities, however, design for real world application context is not formulated.

Wireless, Battery-Free Implants for Electrochemical Catecholamine Sensing and Optogenetic Stimulation.

Neurotransmitters and neuromodulators mediate communication between neurons and other cell types; knowledge of release dynamics is critical to understanding their physiological role in normal and pathological brain function. Investigation into transient neurotransmitter dynamics has largely been hindered due to electrical and material requirements for electrochemical stimulation and recording. Current systems require complex electronics for biasing and amplification and rely on materials that offer limited sensor selectivity and sensitivity.

Open thoracic surgical implantation of cardiac pacemakers in rats.

Genetic engineering and implantable bioelectronics have transformed investigations of cardiovascular physiology and disease. However, the two approaches have been difficult to combine in the same species: genetic engineering is applied primarily in rodents, and implantable devices generally require larger animal models. We recently developed several miniature cardiac bioelectronic devices suitable for mice and rats to enable the advantages of molecular tools and implantable devices to be combined.

Wireless, fully implantable cardiac stimulation and recording with on-device computation for closed-loop pacing and defibrillation.

Monitoring and control of cardiac function are critical for investigation of cardiovascular pathophysiology and developing life-saving therapies. However, chronic stimulation of the heart in freely moving small animal subjects, which offer a variety of genotypes and phenotypes, is currently difficult. Specifically, real-time control of cardiac function with high spatial and temporal resolution is currently not possible.

Wearable devices for continuous monitoring of biosignals: Challenges and opportunities.

The ability for wearable devices to collect high-fidelity biosignals continuously over weeks and months at a time has become an increasingly sought-after characteristic to provide advanced diagnostic and therapeutic capabilities. Wearable devices for this purpose face a multitude of challenges such as formfactors with long-term user acceptance and power supplies that enable continuous operation without requiring extensive user interaction. This review summarizes design considerations associated with these attributes and summarizes recent advances toward continuous operation with high-fidelity biosignal recording abilities.

Moving from Pedagogy to Andragogy in Biomedical Engineering Design: Strategies for Lab-at-Home and Distance Learning.

Engineering design courses are particularly challenging to deliver in online or distance modalities because of the hands-on, collaborative nature of the design process and the need for physical resources and work spaces. In this work, we describe how we rapidly transformed two design courses in the middle two years of the biomedical engineering (BME) program to an online format during the 2019 coronavirus pandemic. In addition to time and safety constraints, we identified access to design spaces with biochemistry, computing, electronic, computing, and manufacturing tools, and team-based learning as major challenges to distance learning in BME design courses.

Nicotine Sensors for Wearable Battery-Free Monitoring of Vaping.

Nicotine, an addictive substance in tobacco products and electronic cigarettes (e-cigs), is recognized for increasing the risk of cardiovascular and respiratory disorders. Careful real-time monitoring of nicotine exposure is critical in alleviating the potential health impacts of not just smokers but also those exposed to second-hand and third-hand smoke. Monitoring of nicotine requires suitable sensing material to detect nicotine selectively and testing under free-living conditions in the standard environment.

Osseosurface electronics-thin, wireless, battery-free and multimodal musculoskeletal biointerfaces.

Bioelectronic interfaces have been extensively investigated in recent years and advances in technology derived from these tools, such as soft and ultrathin sensors, now offer the opportunity to interface with parts of the body that were largely unexplored due to the lack of suitable tools. The musculoskeletal system is an understudied area where these new technologies can result in advanced capabilities. Bones as a sensor and stimulation location offer tremendous advantages for chronic biointerfaces because devices can be permanently bonded and provide stable optical, electromagnetic, and mechanical impedance over the course of years.

Wireless, battery-free, and fully implantable electrical neurostimulation in freely moving rodents.

Implantable deep brain stimulation (DBS) systems are utilized for clinical treatment of diseases such as Parkinson's disease and chronic pain. However, long-term efficacy of DBS is limited, and chronic neuroplastic changes and associated therapeutic mechanisms are not well understood. Fundamental and mechanistic investigation, typically accomplished in small animal models, is difficult because of the need for chronic stimulators that currently require either frequent handling of test subjects to charge battery-powered systems or specialized setups to manage tethers that restrict experimental paradigms and compromise insight.

Wireless, battery-free, subdermally implantable platforms for transcranial and long-range optogenetics in freely moving animals.

Wireless, battery-free, and fully subdermally implantable optogenetic tools are poised to transform neurobiological research in freely moving animals. Current-generation wireless devices are sufficiently small, thin, and light for subdermal implantation, offering some advantages over tethered methods for naturalistic behavior. Yet current devices using wireless power delivery require invasive stimulus delivery, penetrating the skull and disrupting the blood-brain barrier.

Activation of the dorsal, but not the ventral, hippocampus relieves neuropathic pain in rodents.

Accumulating evidence suggests hippocampal impairment under the chronic pain phenotype. However, it is unknown whether neuropathic behaviors are related to dysfunction of the hippocampal circuitry. Here, we enhanced hippocampal activity by pharmacological, optogenetic, and chemogenetic techniques to determine hippocampal influence on neuropathic pain behaviors.

Wireless battery free fully implantable multimodal recording and neuromodulation tools for songbirds.

Wireless battery free and fully implantable tools for the interrogation of the central and peripheral nervous system have quantitatively expanded the capabilities to study mechanistic and circuit level behavior in freely moving rodents. The light weight and small footprint of such devices enables full subdermal implantation that results in the capability to perform studies with minimal impact on subject behavior and yields broad application in a range of experimental paradigms. While these advantages have been successfully proven in rodents that move predominantly in 2D, the full potential of a wireless and battery free device can be harnessed with flying species, where interrogation with tethered devices is very difficult or impossible.

Wireless and battery-free technologies for neuroengineering.

Tethered and battery-powered devices that interface with neural tissues can restrict natural motions and prevent social interactions in animal models, thereby limiting the utility of these devices in behavioural neuroscience research. In this Review Article, we discuss recent progress in the development of miniaturized and ultralightweight devices as neuroengineering platforms that are wireless, battery-free and fully implantable, with capabilities that match or exceed those of wired or battery-powered alternatives. Such classes of advanced neural interfaces with optical, electrical or fluidic functionality can also combine recording and stimulation modalities for closed-loop applications in basic studies or in the practical treatment of abnormal physiological processes.

Soft, wireless and subdermally implantable recording and neuromodulation tools.

Progress in understanding neuronal interaction and circuit behavior of the central and peripheral nervous system (PNS) strongly relies on the advancement of tools that record and stimulate with high fidelity and specificity. Currently, devices used in exploratory research predominantly utilize cables or tethers to provide pathways for power supply, data communication, stimulus delivery and recording, which constrains the scope and use of such devices. In particular, the tethered connection, mechanical mismatch to surrounding soft tissues and bones frustrate the interface leading to irritation and limitation of motion of the subject, which in the case of fundamental and preclinical studies, impacts naturalistic behaviors of animals and precludes the use in experiments involving social interaction and ethologically relevant three-dimensional environments, limiting the use of current tools to mostly rodents and exclude species such as birds and fish.