Injectable ultrasonic sensor for wireless monitoring of intracranial signals.

Direct and precise monitoring of intracranial physiology holds immense importance in delineating injuries, prognostication and averting disease1. Wired clinical instruments that use percutaneous leads are accurate but are susceptible to infection, patient mobility constraints and potential surgical complications during removal2. Wireless implantable devices provide greater operational freedom but include issues such as limited detection range, poor degradation and difficulty in size reduction in the human body3. Here we present an injectable, bioresorbable and wireless metastructured hydrogel (metagel) sensor for ultrasonic monitoring of intracranial signals. The metagel sensors are cubes 2 × 2 × 2 mm3 in size that encompass both biodegradable and stimulus-responsive hydrogels and periodically aligned air columns with a specific acoustic reflection spectrum. Implanted into intracranial space with a puncture needle, the metagel deforms in response to physiological environmental changes, causing peak frequency shifts of reflected ultrasound waves that can be wirelessly measured by an external ultrasound probe. The metagel sensor can independently detect intracranial pressure, temperature, pH and flow rate, realize a detection depth of 10 cm and almost fully degrade within 18 weeks. Animal experiments on rats and pigs indicate promising multiparametric sensing performances on a par with conventional non-resorbable wired clinical benchmarks.

Magnetic soft microfiberbots for robotic embolization.

Cerebral aneurysms and brain tumors are leading life-threatening diseases worldwide. By deliberately occluding the target lesion to reduce the blood supply, embolization has been widely used clinically to treat cerebral aneurysms and brain tumors. Conventional embolization is usually performed by threading a catheter through blood vessels to the target lesion, which is often limited by the poor steerability of the catheter in complex neurovascular networks, especially in submillimeter regions. Here, we propose magnetic soft microfiberbots with high steerability, reliable maneuverability, and multimodal shape reconfigurability to perform robotic embolization in submillimeter regions via a remote, untethered, and magnetically controllable manner. Magnetic soft microfiberbots were fabricated by thermal drawing magnetic soft composite into microfibers, followed by magnetizing and molding procedures to endow a helical magnetic polarity. By controlling magnetic fields, magnetic soft microfiberbots exhibit reversible elongated/aggregated shape morphing and helical propulsion in flow conditions, allowing for controllable navigation through complex vasculature and robotic embolization in submillimeter regions. We performed in vitro embolization of aneurysm and tumor in neurovascular phantoms and in vivo embolization of a rabbit femoral artery model under real-time fluoroscopy. These studies demonstrate the potential clinical value of our work, paving the way for a robotic embolization scheme in robotic settings.

A Laparoscopically Compatible Rapid-Adhesion Bioadhesive for Asymmetric Adhesion, Non-Pressing Hemostasis, and Seamless Seal.

Bioadhesive hydrogels offer unprecedented opportunities in hemostatic agents and tissue sealing; however, the application of existing bioadhesive hydrogels through narrow spaces to achieve strong adhesion in fluid-rich physiological environments is challenged either by undesired indiscriminate adhesion or weak wet tissue adhesion. Here, a laparoscopically compatible asymmetric adhesive hydrogel (aAH) composed of sprayable adhesive hydrogel powders and injectable anti-adhesive glue is proposed for hemostasis and to seal the bloody tissues in a non-pressing way, allowing for preventing postoperative adhesion. The powders can seed on the irregular bloody wound to rapidly absorb interfacial fluid, crosslink, and form an adhesive hydrogel to hemostatic seal (blood clotting time and tissue sealing in 10 s, ≈200 mm Hg of burst pressure in sealed porcine tissues). The aAH can be simply formed by crosslinking the upper powder with injectable glue to prevent postoperative adhesion (adhesive strength as low as 1 kPa). The aAH outperforms commercial hemostatic agents and sealants in the sealing of bleeding organs in live rats, demonstrating superior anti-adhesive efficiency. Further, the hemostatic seamless sealing by aAH succeeds in shortening the time of warm ischemia, decreasing the blood loss, and reducing the possibility of rebleeding in the porcine laparoscopic partial nephrectomy model.

Bioinspired Soft Elastic Metamaterials for Reconstruction of Natural Hearing.

Natural hearing which means hearing naturally like normal people is critical for patients with hearing loss to participate in life. Cochlear implants have enabled numerous severe hearing loss patients to hear voice functionally, while cochlear implant users can hardly distinguish different tones or appreciate music subject to the absence of rate coding and insufficient frequency channels. Here a bioinspired soft elastic metamaterial that reproduces the shape and key functions of the human cochlea is reported. Inspired by human cochlea, the metamaterials are designed to possess graded microstructures with high effective refractive index distributed on a spiral shape to implement position-related frequency demultiplexing, passive sound enhancements of 10 times, and high-speed parallel processing of 168-channel sound/piezoelectric signals. Besides, it is demonstrated that natural hearing artificial cochlea has fine frequency resolution up to 30 Hz, a wide audible range from 150-12 000 Hz, and a considerable output voltage that can activate the auditory pathway in mice. This work blazes a promising trail for reconstruction of natural hearing in patients with severe hearing loss.

Inverse-Designed Aid Lenses for Precise Correction of Color Vision Deficiency.

Color vision deficiency (CVD) is a common ocular disorder affecting more than 300 million people on the earth. Although no clinical cure for the disorder currently exists, some specialized color filtering glasses/lenses based on dyes, metasurfaces, or nanocomposites have been employed for CVD management. However, as CVD patients usually diversify in their classification and severity, none of the current lenses provides a customized correction for various CVD patients, resulting in undesirable correction effects. Here, we present an inverse-designed approach for the precise correction of CVD. The wavelength shift of a patient's abnormal cone photoreceptors was measured to inversely design the best blocking wavelength and blocking rate of the lens. Then the customized aid lenses were fabricated using silica-coated gold nanoparticles with appropriate sizes and concentrations, verified by the simulated color vision and human tests. This study demonstrates the potential of the inverse-designed aid lenses in precise color filtering and customized CVD management.

Soft and disordered hyperuniform elastic metamaterials for highly efficient vibration concentration.

Vibrations, which widely exist throughout the world, could be a nearly endless and locally obtained green energy source. It has been a long-standing challenge to efficiently utilize dispersed vibration energy, especially within the high-frequency range, since the amplitudes of high-frequency vibrations in local parts of objects are relatively weak. Here, for the first time, we propose a soft and disordered hyperuniform elastic metamaterial (DHEM), achieving a remarkable concentration of vibrations in broad frequency bands by a maximum enhancement factor of ∼4000 at 1930 Hz. The DHEM, with rational sizes from ∼1 cm to ∼1000 cm, covers a broad range of frequencies from ∼10 Hz to ∼10 kHz, which are emitted by many vibration sources including domestic appliances, factories and transportation systems, for example. Moreover, the performance of the soft DHEM under deformation is validated, enabling conformal attachments on uneven objects. Our findings lay the groundwork for reducing traditional energy consumption by recovering some of the energy dissipated by devices in the working world.

Ferromagnetic soft catheter robots for minimally invasive bioprinting.

In vivo bioprinting has recently emerged as a direct fabrication technique to create artificial tissues and medical devices on target sites within the body, enabling advanced clinical strategies. However, existing in vivo bioprinting methods are often limited to applications near the skin or require open surgery for printing on internal organs. Here, we report a ferromagnetic soft catheter robot (FSCR) system capable of in situ computer-controlled bioprinting in a minimally invasive manner based on magnetic actuation. The FSCR is designed by dispersing ferromagnetic particles in a fiber-reinforced polymer matrix. This design results in stable ink extrusion and allows for printing various materials with different rheological properties and functionalities. A superimposed magnetic field drives the FSCR to achieve digitally controlled printing with high accuracy. We demonstrate printing multiple patterns on planar surfaces, and considering the non-planar surface of natural organs, we then develop an in situ printing strategy for curved surfaces and demonstrate minimally invasive in vivo bioprinting of hydrogels in a rat model. Our catheter robot will permit intelligent and minimally invasive bio-fabrication.