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Physically transient forms of electronics enable unique classes of technologies, ranging from biomedical implants that disappear through processes of bioresorption after serving a clinical need to internet-of-things devices that harmlessly dissolve into the environment following a relevant period of use. Here, we develop a sustainable manufacturing pathway, based on ultrafast pulsed laser ablation, that can support high-volume, cost-effective manipulation of a diverse collection of organic and inorganic materials, each designed to degrade by hydrolysis or enzymatic activity, into patterned, multi-layered architectures with high resolution and accurate overlay registration. The technology can operate in patterning, thinning and/or cutting modes with (ultra)thin eco/bioresorbable materials of different types of semiconductors, dielectrics, and conductors on flexible substrates. Component-level demonstrations span passive and active devices, including diodes and field-effect transistors. Patterning these devices into interconnected layouts yields functional systems, as illustrated in examples that range from wireless implants as monitors of neural and cardiac activity, to thermal probes of microvascular flow, and multi-electrode arrays for biopotential sensing. These advances create important processing options for eco/bioresorbable materials and associated electronic systems, with immediate applicability across nearly all types of bioelectronic studies.

 

A Correction to this paper has been published: https://doi.org/10.1038/s41467-020-20857-y 

Continuous measurements of pressure and temperature within the intracranial, intraocular, and intravascular spaces provide essential diagnostic information for the treatment of traumatic brain injury, glaucoma, and cardiovascular diseases, respectively. Optical sensors are attractive because of their inherent compatibility with magnetic resonance imaging (MRI). Existing implantable optical components use permanent, nonresorbable materials that must be surgically extracted after use. Bioresorbable alternatives, introduced here, bypass this requirement, thereby eliminating the costs and risks of surgeries. Here, millimeter-scale bioresorbable Fabry-Perot interferometers and two dimensional photonic crystal structures enable precise, continuous measurements of pressure and temperature. Combined mechanical and optical simulations reveal the fundamental sensing mechanisms. In vitro studies and histopathological evaluations quantify the measurement accuracies, operational lifetimes, and biocompatibility of these systems. In vivo demonstrations establish clinically relevant performance attributes. The materials, device designs, and fabrication approaches outlined here establish broad foundational capabilities for diverse classes of bioresorbable optical sensors. 

Abstract Bioresorbable electronic stimulators are of rapidly growing interest as unusual therapeutic platforms, i.e., bioelectronic medicines, for treating disease states, accelerating wound healing processes and eliminating infections. Here, we present advanced materials that support operation in these systems over clinically relevant timeframes, ultimately bioresorbing harmlessly to benign products without residues, to eliminate the need for surgical extraction. Our findings overcome key challenges of bioresorbable electronic devices by realizing lifetimes that match clinical needs. The devices exploit a bioresorbable dynamic covalent polymer that facilitates tight bonding to itself and other surfaces, as a soft, elastic substrate and encapsulation coating for wireless electronic components. We describe the underlying features and chemical design considerations for this polymer, and the biocompatibility of its constituent materials. In devices with optimized, wireless designs, these polymers enable stable, long-lived operation as distal stimulators in a rat model of peripheral nerve injuries, thereby demonstrating the potential of programmable long-term electrical stimulation for maintaining muscle receptivity and enhancing functional recovery. 

Measurements of regional internal body temperatures can yield important information in the diagnosis of immune response‐related anomalies, for precisely managing the effects of hyperthermia and hypothermia therapies and monitoring other transient body processes such as those associated with wound healing. Current approaches rely on permanent implants that require extraction surgeries after the measurements are no longer needed. Emerging classes of bioresorbable sensors eliminate the requirements for extraction, but their use of percutaneous wires for data acquisition leads to risks for infection at the suture site. As an alternative, a battery‐free, wireless implantable device is reported here, which is constructed entirely with bioresorbable materials for monitoring regional internal body temperatures over clinically relevant timeframes. Ultimately, these devices disappear completely in the body through natural processes. In vivo demonstrations indicate stable operation as subcutaneous and intracranial implants in rat models for up to 4 days. Potential applications include monitoring of healing cascades associated with surgical wounds, recovery processes following internal injuries, and the progression of thermal therapies for various conditions.

 

Pressures in the intracranial, intraocular, and intravascular spaces are important parameters in assessing patients with a range of conditions, of particular relevance to those recovering from injuries or from surgical procedures. Compared with conventional devices, sensors that disappear by natural processes of bioresorption offer advantages in this context, by eliminating the costs and risks associated with retrieval. A class of bioresorbable pressure sensor that is capable of operational lifetimes as long as several weeks and physical lifetimes as short as several months, as combined metrics that represent improvements over recently reported alternatives, is presented. Key advances include the use of 1) membranes of monocrystalline silicon and blends of natural wax materials to encapsulate the devices across their top surfaces and perimeter edge regions, respectively, 2) mechanical architectures to yield stable operation as the encapsulation materials dissolve and disappear, and 3) additional sensors to detect the onset of penetration of biofluids into the active sensing areas. Studies that involve monitoring of intracranial pressures in rat models over periods of up to 3 weeks demonstrate levels of performance that match those of nonresorbable clinical standards. Many of the concepts reported here have broad applicability to other classes of bioresorbable technologies.

 

Bioresorbable electronic technologies form the basis for classes of biomedical devices that undergo complete physical and chemical dissolution after a predefined operational period, thereby eliminating the costs and risks associated with secondary surgical extraction. A continuing area of opportunity is in the development of strategies for power supply for these systems, where previous studies demonstrate some utility for biodegradable batteries, radio frequency harvesters, solar cells, and others. This paper introduces a type of bioresorbable system for wireless power transfer, in which a rotating magnet serves as the transmitter and a bioresorbable antenna as the remote receiver, with capabilities for operation at low frequencies (<200 Hz). Systematic experimental and numerical studies demonstrate several unique advantages of this system, most significantly the elimination of impedance matching and electromagnetic radiation exposure presented with the types of radio frequency energy harvesters explored previously. These results add to the portfolio of power supply options in bioresorbable electronic implants.