A supramolecular elastic polymer that is stable in the acidic environment of the stomach but dissolves in the neutral-pH environment of the intestines is shown to function as a safe gastric-retentive device in pigs.
This collection of papers from Nature Research and Reviews journals displays recent developments in materials science, electronics and biology of bioelectronic devices developed to communicate with different human tissues and organs. By showcasing new devices and approaches for engineering bioelectronic interfaces, it demonstrates the progress in understanding and designing electronic device-human interactions, specifically in the context of the cardiovascular system, nervous system, gastrointestinal tract, skin and musculoskeletal system.
The collection is curated by the Bioengineering and Biomaterials editorial community and published simultaneously to the beginning of the Nature Conference on 2D Flexible Electronics.
Nature Conference on Flexible Electronics - Visions of a Flexible Future
October 12-14, 2018
Jin Jiang International Hotel, Xi'an, China
This Nature conference on the theme of flexible electronics will set its sights firmly on the future, by exploring how flexible electronics will impact society by helping to tackle challenges in areas such as health, energy, ubiquitous electronics and the "Internet of Things".
An endoscope with integrated transparent bioelectronics and theranostic nanoparticles for colon cancer treatment
Current endoscopes are limited to detection or treatment of colon cancers and growths, or resolution is too low for clinical application. Here the authors present a multimodal endoscope with theranostic nanoparticles that integrates fluorescence-based mapping, electrical impedance, pH and temperature monitoring, RF ablation and localized phototherapy or chemotherapy.
A biocompatible, energy-harvesting electrochemical cell delivers power to a wireless sensor for an average of 6.1 days of temperature measurements in the gastrointestinal tract of pigs.
Soft small robots offer the opportunity to non-invasively access human tissue to perform medical operations and deliver drugs; however, challenges in materials design, biocompatibility and function control remain to be overcome for soft robots to reach the clinic.
In a human pilot trial, ingestible electronic capsules, which can sense oxygen, hydrogen, and carbon dioxide gas in the gut, have been shown to be capable of monitoring changes in a person’s diet.
An ingestible, flexible piezoelectric sensor that senses mechanical deformations in the gastric cavity allows for the monitoring of ingestion states in the gastrointestinal tract of pigs.
Engineered hybrid cardiac patches with multifunctional electronics for online monitoring and regulation of tissue function
Integrating multifunctional electronics with engineered cardiac patches enables the recording of cellular electrical activities, and on-demand provision of electrical stimulation and release of drugs.
Heart-on-a-chip devices with integrated strain gauges for direct readout of tissue contractile strength allow for multiplexed drug-dose experiments and studies of functional maturation of cardiac tissue.
Highly conductive, stretchable and biocompatible Ag–Au core–sheath nanowire composite for wearable and implantable bioelectronics
A highly conductive, biocompatible and stretchable nanocomposite based on ultralong gold-coated silver nanowires allows for the realization of wearable and implantable bioelectronics.
Three-dimensional mapping and regulation of action potential propagation in nanoelectronics-innervated tissues
Three-dimensional tissue-scaffold-mimicking nanoelectronics are used to map conduction pathways during cardiac tissue development, record action potential dynamics in disease and pharmacological models, and actively control action potential propagation.
An ultrasonic and stretchable device conformal to the skin that captures blood pressure waveforms at deeply embedded arterial and venous sites enables the continuous monitoring of cardiovascular events.
In this Review, Yacoub and McLeod summarize the rationale for monitoring patients with heart failure or pulmonary arterial hypertension to detect haemodynamic changes that predict the deterioration from subclinical to overt disease, the transition from noninvasive to implantable devices and the current and anticipated clinical use of these devices.
In this Review, the authors discuss the epidemiology, diagnosis and optimal management of resistant hypertension. They highlight the limitations of clinical trials of device-based therapies conducted to date and propose directions for future research.
Conduction system disorders lead to slow heart rates that are insufficient to support the circulation, necessitating implantation of electronic pacemakers. Current pacemakers, although effective, have limitations including lead malfunction, lack of autonomic responsiveness, and device-related infections. In this Review, Marbán and colleagues discuss next-generation electronic devices designed to address current limitations, as well as biological pacemakers as alternatives to implantable hardware.
Cardiac implanted electronic devices (CIEDs) frequently detect subclinical atrial high-rate episodes (AHREs), but the relevance and appropriate clinical response to these episodes is uncertain. In this Review, Freedman and colleagues discuss the relationship between AHREs, atrial fibrillation, and risk of stroke, and propose a management algorithm for patients with CIED-detected AHREs.
Skin and Musculoskeletal system
Human sweat is attracting attention as a carrier of biomarkers of potential diagnostic importance, as well as in drug abuse detection and athletic performance optimization. In particular, sweat is much more tractable than other body fluids for continuous bio-monitoring. This paper presents a fully integrated flexible sensor platform for sweat analysis, based on existing technologies. Ali Javey and colleagues successfully connect plastic-based skin sensors to conventional silicon integrated circuitry to achieve multiple simultaneous measurement of sweat metabolites (glucose and lactate) and electrolytes (sodium and potassium). Skin temperature was measured to provide in situ calibration of the sensors. A small cohort human subject validation was performed to demonstrate the practical value of the platform — and a specially designed Android app created — for real-time assessment of physiological status, either as a wristband or forehead patch.
Flexible electronics have a range of potential medical applications, particularly for devices that need to integrate seamlessly with humans. But to get the most out of such systems, the circuitry ideally needs to be stretchable as well as flexible, much like human skin. Zhenan Bao and colleagues have been exploring a strategy for achieving this combination of properties using polymeric electronic materials that are intrinsically stretchable. Now they demonstrate a scalable fabrication process in which such materials can be used to produce large-area, skin-like, electronic circuitry that can be bent and stretched while retaining its desirable electronic functionality.
The electric eel can generate electrical discharges of 100 watts to stun prey, but should you X-ray an eel, you wouldn't find a battery pack inside. Instead, thousands of cells called electrocytes are arranged along its body, each producing a small ion gradient and therefore a potential difference across them. Now, Michael Mayer and colleagues have developed a hydrogel-based system that mimics the electrocyte mechanism and could be used as a soft power source for robotics. They arrange sets of ion-selective hydrogels in series to generate ion gradients across a group of four hydrogel droplets. These droplets can either be arranged in series in a microfluidic set-up, or be stacked in parallel by folding up an array of hydrogels using origami principles. The net result is a power source that is able to generate voltages similar to those generated by the electric eel.
This Review Article examines the development of wearable sweat sensors, considering the challenges and opportunities for such technology in the context of personalized healthcare.
Stretchable temperature-sensing circuits with strain suppression based on carbon nanotube transistors
Using carbon nanotube transistors, stretchable temperature sensor circuits can be designed that suppress strain-dependent errors and achieve a measured inaccuracy of only ±1 °C within a uniaxial strain range of 0–60%
Implantable pressure and strain sensors based on biodegradable materials have been designed to naturally decompose after their useful lifetime, eliminating the need for surgical extraction of the device.
Breathable and stretchable fibrous mesh electrical interconnects directly attached to human skin can serve as components of on-skin sensors.
An integrated self-healable electronic skin system fabricated via dynamic reconstruction of a nanostructured conducting network
Self-reconstruction of conducting nanostructures assisted by a dynamically crosslinked polymer network enables the fabrication of autonomous self-healable and stretchable multi-component electronic skin.
This Review discusses the materials and electronic requirements for flexible sensors and electronic systems to mimic the mechanical and sensing properties of natural skin, with the goal of providing artificial prostheses with sensing capabilities.
Electronic skins have been developed to emulate human sensory systems, but simultaneous detection of multiple stimuli remains a big challenge due to coupling of electronic signals. Here, Hua et al. overcome this problem in a stretchable and conformable matrix network integrated with seven different modes.
Soft robots have broad applications in medicine. In this Review, biomedical applications, including surgery, drug delivery, prostheses, wearable devices and artificial organs, are discussed in the context of materials, actuation strategies and challenges.
Advances in electronic devices have opened opportunities for extracting a variety of data from the human body, and for the treatment of diseases. In this Review, tissue properties affecting device integration are described and electronic systems interfacing with organs and engineered tissues are highlighted.
Hydrogel ionotronics employ hydrogels as stretchable, transparent, ionic conductors for the development of ionotronic devices, such as artificial muscles, skins and axons. This Review discusses the mechanical properties and chemistry of materials for hydrogel ionotronic devices and highlights possible applications.
Soft robots promise solutions for a wide range of applications that cannot be achieved with traditional, rigid-component robots. A key challenge is the creation of robotic structures that can vary their stiffness at will, for example, by using antagonistic actuators, to optimize their interaction with the environment and be able to exert high forces.
Sensory, motor and cognitive operations involve the coordinated action of large neuronal populations across multiple brain regions. Existing technologies reliably measure activity from a relatively small number of neurons with high spatial and temporal resolution, or from a large volume of neurons with low resolution. Timothy Harris and colleagues describe the design, fabrication and performance of Neuropixels, a silicon probe that can measure well-isolated neural activity from hundreds of neurons. They integrated these probes into a lightweight system that could record activity simultaneously and with high fidelity from hundreds of neurons in awake and freely moving rodents.
Rolled-up ultraflexible mesh electronics can be injected through a syringe needle of diameter as small as 100 μm into man-made and biological cavities, gels and tissues, where they can unfold and perform sensing operations.
Plasmonic meta-electrodes allow intracellular recordings at network level on high-density CMOS-multi-electrode arrays
A combination of planar porous electrodes, optoacoustic poration and laser scanning allows large-scale recording of intracellular action potentials of cardiomyocyte cultures on CMOS-MEAs.
The wireless and photoelectrochemical stimulation of primary rat dorsal root ganglion neurons is demonstrated by shining laser light onto coaxially doped silicon nanowires deposited on the neuronal membrane.
Bioresorbable silicon electronics for transient spatiotemporal mapping of electrical activity from the cerebral cortex
Arrays of bioresorbable, highly doped silicon electrodes with multiplexing capabilities are used as electrocorticography sensors to perform in vivo, reliable acute and chronic recordings for up to one month before dissolving in the body.
Minimally invasive endovascular stent-electrode array for high-fidelity, chronic recordings of cortical neural activity
Cortical activity can be monitored for 6 months or longer from within the brain vasculature using an endovascular stent-electrode array.
Intracellular, intercellular and extracellular silicon interfaces enable light-controlled non-genetic modulation of intracellular calcium dynamics, of cellular excitability, of neurotransmitter release from brain slices, and of brain activity in vivo.
Flexible mesh electronics facilitate stable long-term recordings of the same single neurons in mouse brains over months, enabling chronic recordings in behaving animals and longitudinal studies to resolve aging-dependent changes in neural activity.
A miniature light-field microscope in combination with a signal-extraction approach enables high-speed volumetric calcium imaging in freely moving mice.
A photovoltaic retinal prosthesis activated by light restores half of normal visual acuity in rats blinded by retinal degeneration.
Spatiotemporal neuromodulation therapies engaging muscle synergies improve motor control after spinal cord injury
Analysis of synergistic muscle activations during locomotion and anatomical tracing of muscle synergy representations in the rodent spinal cord guide the development of a new spinal implant for neuromodulation therapy. In multiple rodent models of spinal cord injury, spatiotemporal stimulation that mimics naturalistic muscle activation patterns promotes improved functional recovery over previously described continuous stimulation protocols.
Soft transparent graphene contact lens electrodes for conformal full-cornea recording of electroretinogram
The electrical response of the eye to optical stimulus is important in disease diagnosis but current electrodes used have limitations. Here, the authors report on the development of soft transparent graphene-based contact lens electrodes for electroretinogram recording and test the device in vivo.
Coupling fluorescence imaging with fMRI allows study of the molecular processes underlying physiological responses. This protocol shows how to use a fiber-optic implant to measure calcium signaling and blood oxygenation (BOLD fMRI) simultaneously.
Implantable neuroprostheses communicate with the nervous system to provide diagnosis or therapy to the injured body. In this review, we discuss materials-based approaches to overcome the physical and mechanical mismatch at the tissue–implant interface and to design long-term neurointegrated prostheses.
Understanding the dynamics and architecture of the nervous system requires tools for recording and modulating the activity of billions of neurons. This Review explores the history of neural engineering and the materials innovation at the interface between neural tissue and synthetic sensors.
This Review discusses the role of glia as an effector of the performance and integration of devices implanted in the brain, and the implications of this for device development.