Stanford Advisors


All Publications


  • High-density soft bioelectronic fibres for multimodal sensing and stimulation. Nature Khatib, M., Zhao, E. T., Wei, S., Park, J., Abramson, A., Bishop, E. S., Thomas, A. L., Chen, C. H., Emengo, P., Xu, C., Hamnett, R., Root, S. E., Yuan, L., Wurdack, M. J., Zaluska, T., Lee, Y., Parkatzidis, K., Yu, W., Chakhtoura, D., Kim, K. K., Zhong, D., Nishio, Y., Zhao, C., Wu, C., Jiang, Y., Zhang, A., Li, J., Wang, W., Salimi-Jazi, F., Rafeeqi, T. A., Hemed, N. M., Tok, J. B., Qian, X., Chen, X., Kaltschmidt, J. A., Dunn, J. C., Bao, Z. 2025; 645 (8081): 656-664

    Abstract

    There is an increasing demand for multimodal sensing and stimulation bioelectronic fibres for both research and clinical applications1,2. However, existing fibres suffer from high rigidity, low component layout precision, limited functionality and low density of active components. These limitations arise from the challenge of integrating many components into one-dimensional fibre devices, especially owing to the incompatibility of conventional microfabrication methods (for example, photolithography) with curved, thin and long fibre structures2. As a result, limited applications have been demonstrated so far. Here we use 'spiral transformation' to convert two-dimensional thin films containing microfabricated devices into one-dimensional soft fibres. This approach allows for the fabrication of high-density multimodal soft bioelectronic fibres, termed Spiral-NeuroString (S-NeuroString), while enabling precise control on the longitudinal, angular and radial positioning and distribution of the functional components. Taking advantage of the biocompatibility of our soft fibres with the dynamic and soft gastrointestinal system, we proceed to show the feasibility of our S-NeuroString for post-operative multimodal continuous motility mapping and tissue stimulation in awake pigs. We further demonstrate multi-channel single-unit electrical recording in mouse brain for up to 4 months, and a fabrication capability to produce 1,280 channels within a 230-μm-diameter soft fibre. Our soft bioelectronic fibres offer a powerful platform for minimally invasive implantable electronics, where diverse sensing and stimulation functionalities can be effectively integrated.

    View details for DOI 10.1038/s41586-025-09481-2

    View details for PubMedID 40962977

    View details for PubMedCentralID 6397644

  • Nanoporous Plasmonic Microneedle Arrays Induced High-Efficiency Intracellular Delivery of Metabolism Regulating Protein. Small (Weinheim an der Bergstrasse, Germany) Ji, Z., He, L., Sun, M., Lv, M., Chen, R., Zhao, C., Ma, L., Cheng, J., Qin, J., Xu, X., Fan, Z. 2025: e2412106

    Abstract

    Patterned micro/nanostructure arrays have shown the potential to effectively regulate cellular behavior, and their unique microstructure may address the limitations of conventional pore materials, leading to novel phenomena. In this work, a large-area gold micro/nano-array substrate with an average hole of ≈32 nm is designed and extensively screened. Precisely engineered nanopores on the substrate can effectively improve photothermal conversion efficiency, and instant heat dissipation in the absence of laser irradiation. The mesoporous arrays are fabricated by hybrid lithography, offering advantages such as simple processing, high reproducibility, and immense commercial potential. Notably, its heating rate is as rapid as ≈45 K µs-1 at low power levels, with the cooling duration reduced to ≈50 µs after the laser irradiation. Metabolism regulatory proteins such as cytochrome C (CytoC) and β-galactosidase (β-gal) can be efficiently introduced into the U87 cell model without inducing phototoxicity or protein inactivation, maintaining catalytic activity to modulate the cellular metabolic state. This delivery platform based on transient nano-cyclones stimulating cell perturbations can be further expanded through modulated microstructures, such as delivering functional proteins or biomolecules for efficient intracellular regulation, cellular transfection, and in the future application as a potential high-throughput screening tool for clustered regularly interspaced short palindromic repeats (CAR-T) biopharmaceutical and clustered regularly interspaced short palindromic repeats (CRISPR) technologies.

    View details for DOI 10.1002/smll.202412106

    View details for PubMedID 40042405

  • A Transparent, Patternable, and Stretchable Conducting Polymer Solid Electrode for Dielectric Elastomer Actuators ADVANCED FUNCTIONAL MATERIALS Kim, E., Lai, J., Michalek, L., Wang, W., Xu, C., Lyu, H., Yu, W., Park, H., Tomo, Y., Root, S. E., Lee, B., Park, J., Park, B., Wei, S., Zhao, C., Bao, Z. 2024
  • Skin-inspired soft bioelectronic materials, devices and systems NATURE REVIEWS BIOENGINEERING Zhao, C., Park, J., Root, S. E., Bao, Z. 2024; 2 (8): 671-690
  • High-speed and large-scale intrinsically stretchable integrated circuits. Nature Zhong, D., Wu, C., Jiang, Y., Yuan, Y., Kim, M., Nishio, Y., Shih, C., Wang, W., Lai, J., Ji, X., Gao, T. Z., Wang, Y., Xu, C., Zheng, Y., Yu, Z., Gong, H., Matsuhisa, N., Zhao, C., Lei, Y., Liu, D., Zhang, S., Ochiai, Y., Liu, S., Wei, S., Tok, J. B., Bao, Z. 2024; 627 (8003): 313-320

    Abstract

    Intrinsically stretchable electronics with skin-like mechanical properties have been identified as a promising platform for emerging applications ranging from continuous physiological monitoring to real-time analysis of health conditions, to closed-loop delivery of autonomous medical treatment1-7. However, current technologies could only reach electrical performance at amorphous-silicon level (that is, charge-carrier mobility of about 1cm2V-1s-1), low integration scale (for example, 54 transistors per circuit) and limited functionalities8-11. Here we report high-density, intrinsically stretchable transistors and integrated circuits with high driving ability, high operation speed and large-scale integration. They were enabled by a combination of innovations in materials, fabrication process design, device engineering and circuit design. Our intrinsically stretchable transistors exhibit an average field-effect mobility of more than 20cm2V-1s-1 under 100% strain, a device density of 100,000 transistors per cm2, including interconnects and a high drive current of around 2muAmum-1 at a supply voltage of 5V. Notably, these achieved parameters are on par with state-of-the-art flexible transistors based on metal-oxide, carbon nanotube and polycrystalline silicon materials on plastic substrates12-14. Furthermore, we realize a large-scale integrated circuit with more than 1,000 transistors and a stage-switching frequency greater than 1MHz, for the first time, to our knowledge, in intrinsically stretchable electronics. Moreover, we demonstrate a high-throughput braille recognition system that surpasses human skin sensing ability, enabled by an active-matrix tactile sensor array with a record-high density of 2,500 units per cm2, and a light-emitting diode display with a high refreshing speed of 60Hz and excellent mechanical robustness. The above advancements in device performance have substantially enhanced the abilities of skin-like electronics.

    View details for DOI 10.1038/s41586-024-07096-7

    View details for PubMedID 38480964

  • Spiral NeuroString: High-Density Soft Bioelectronic Fibers for Multimodal Sensing and Stimulation. bioRxiv : the preprint server for biology Khatib, M., Zhao, E. T., Wei, S., Abramson, A., Bishop, E. S., Chen, C., Thomas, A., Xu, C., Park, J., Lee, Y., Hamnett, R., Yu, W., Root, S. E., Yuan, L., Chakhtoura, D., Kim, K. K., Zhong, D., Nishio, Y., Zhao, C., Wu, C., Jiang, Y., Zhang, A., Li, J., Wang, W., Salimi-Jazi, F., Rafeeqi, T. A., Hemed, N. M., Tok, J. B., Chen, X., Kaltschmidt, J. A., Dunn, J. C., Bao, Z. 2023

    Abstract

    Bioelectronic fibers hold promise for both research and clinical applications due to their compactness, ease of implantation, and ability to incorporate various functionalities such as sensing and stimulation. However, existing devices suffer from bulkiness, rigidity, limited functionality, and low density of active components. These limitations stem from the difficulty to incorporate many components on one-dimensional (1D) fiber devices due to the incompatibility of conventional microfabrication methods (e.g., photolithography) with curved, thin and long fiber structures. Herein, we introduce a fabrication approach, ‶spiral transformation, to convert two-dimensional (2D) films containing microfabricated devices into 1D soft fibers. This approach allows for the creation of high density multimodal soft bioelectronic fibers, termed Spiral NeuroString (S-NeuroString), while enabling precise control over the longitudinal, angular, and radial positioning and distribution of the functional components. We show the utility of S-NeuroString for motility mapping, serotonin sensing, and tissue stimulation within the dynamic and soft gastrointestinal (GI) system, as well as for single-unit recordings in the brain. The described bioelectronic fibers hold great promises for next-generation multifunctional implantable electronics.

    View details for DOI 10.1101/2023.10.02.560482

    View details for PubMedID 37873341

  • Environmentally stable and stretchable polymer electronics enabled by surface-tethered nanostructured molecular-level protection. Nature nanotechnology Zheng, Y., Michalek, L., Liu, Q., Wu, Y., Kim, H., Sayavong, P., Yu, W., Zhong, D., Zhao, C., Yu, Z., Chiong, J. A., Gong, H., Ji, X., Liu, D., Zhang, S., Prine, N., Zhang, Z., Wang, W., Tok, J. B., Gu, X., Cui, Y., Kang, J., Bao, Z. 2023

    Abstract

    Stretchable polymer semiconductors (PSCs) are essential for soft stretchable electronics. However, their environmental stability remains a longstanding concern. Here we report a surface-tethered stretchable molecular protecting layer to realize stretchable polymer electronics that are stable in direct contact with physiological fluids, containing water, ions and biofluids. This is achieved through the covalent functionalization of fluoroalkyl chains onto a stretchable PSC film surface to form densely packed nanostructures. The nanostructured fluorinated molecular protection layer (FMPL) improves the PSC operational stability over an extended period of 82 days and maintains its protection under mechanical deformation. We attribute the ability of FMPL to block water absorption and diffusion to its hydrophobicity and high fluorination surface density. The protection effect of the FMPL (~6 nm thickness) outperforms various micrometre-thick stretchable polymer encapsulants, leading to a stable PSC charge carrier mobility of ~1 cm2 V-1 s-1 in harsh environments such as in 85-90%-humidity air for 56 days or in water or artificial sweat for 42 days (as a benchmark, the unprotected PSC mobility degraded to 10-6 cm2 V-1 s-1 in the same period). The FMPL also improved the PSC stability against photo-oxidative degradation in air. Overall, we believe that our surface tethering of the nanostructured FMPL is a promising approach to achieve highly environmentally stable and stretchable polymer electronics.

    View details for DOI 10.1038/s41565-023-01418-y

    View details for PubMedID 37322142

  • Neuromorphic sensorimotor loop embodied by monolithically integrated, low-voltage, soft e-skin. Science (New York, N.Y.) Wang, W., Jiang, Y., Zhong, D., Zhang, Z., Choudhury, S., Lai, J. C., Gong, H., Niu, S., Yan, X., Zheng, Y., Shih, C. C., Ning, R., Lin, Q., Li, D., Kim, Y. H., Kim, J., Wang, Y. X., Zhao, C., Xu, C., Ji, X., Nishio, Y., Lyu, H., Tok, J. B., Bao, Z. 2023; 380 (6646): 735-742

    Abstract

    Artificial skin that simultaneously mimics sensory feedback and mechanical properties of natural skin holds substantial promise for next-generation robotic and medical devices. However, achieving such a biomimetic system that can seamlessly integrate with the human body remains a challenge. Through rational design and engineering of material properties, device structures, and system architectures, we realized a monolithic soft prosthetic electronic skin (e-skin). It is capable of multimodal perception, neuromorphic pulse-train signal generation, and closed-loop actuation. With a trilayer, high-permittivity elastomeric dielectric, we achieved a low subthreshold swing comparable to that of polycrystalline silicon transistors, a low operation voltage, low power consumption, and medium-scale circuit integration complexity for stretchable organic devices. Our e-skin mimics the biological sensorimotor loop, whereby a solid-state synaptic transistor elicits stronger actuation when a stimulus of increasing pressure is applied.

    View details for DOI 10.1126/science.ade0086

    View details for PubMedID 37200416