Summary:
UCLA researchers in the Department of Materials Science and Engineering have developed a novel self-softening and biocompatible polymer to be used in a neural probe.
Background:
Implantable bioelectronics are revolutionizing the diagnosis and treatment of neurological and neuropsychiatric disorders. Compared with noninvasive approaches, implanted neural interfaces can record signals and control brain activity with greater precision in the location of recording and maintain this accuracy over an extended period. However, there is a significant challenge from the mechanical stiffness disparity between state-of-the-art rigid devices compared to the soft tissues of the central nervous system. The mechanical mismatch is around six orders of magnitude, posing significant risks such as tissue damage, decreased recording accuracy, and eventual device failure. To address these issues, there is a critical need for the development of devices that utilize soft materials with moduli that more closely resemble that of tissue. Such materials can mitigate inflammatory responses and support long-term, high-quality neural recording and modulation.
Existing soft polymers typically have a thickness of less than 10 m, making implantation and handling challenging and unreliable. Consequently, rigid insertion shuttles and sacrificial stiff coatings are often used in conjunction with these soft polymer probes to aid in initial tissue implantation. Unfortunately, this adds additional fabrication steps, and the insertion process may cause further tissue damage. Therefore, there is an urgent need for an all-in-one polymeric probe capable of both penetrating tissues initially with rigidity and adapting to tissue softness for accurate reading and neuromodulation. Such material would allow for a streamlined insertion process, minimize tissue trauma, and enhance the effectiveness of neural interfaces.
Innovation:
UCLA researchers have developed a body-temperature triggered adaptive polymer. This innovative material mimics the stiffness of natural tissues at body temperature while remaining rigid at room temperature. The polymer’s thermal adaptiveness is achieved through nanoscale crystallizable networks, allowing it to transition its stiffness by over three orders of magnitude in just 10 seconds. These advanced polymers have been integrated into a groundbreaking multimodal neural probe with a plurality of transistors and electrodes to allow for neurochemical sensing, including serotonin quantification. As this self-softening polymer provides the rigidity necessary for implantation, no shuttle device or assistive device is necessary for implantation. Furthermore, these neural probes remain compatible with complex device fabrication processes currently utilized for current devices, ensuring a seamless transition to the fabrication and utilization of these novel neural probes.
Potential Applications:
• Neurological and neuropsychiatric surgeries
• Implantable bioelectronics
• Drug Delivery Systems
• Catheters and Stents
• Soft Robotics
• Smart Materials
• Wearable sensors
Advantages:
• Multimodal probe with plurality of transistors with different DNA aptamers for neurochemical sensing
• Elastic Modulus ~0.2 GPa at room temperature and ~10 kPa at body temperature
• Does not require a shuttle device or other assistive device to penetrate tissues
• Switch stiffness over three orders of magnitude within 10 seconds
• Record accurate and reliable readings from neural modulation
Development-To-Date:
This novel polymeric neural probe was successfully used in ex vivo and in vivo experiments to investigate sensor reliability. A peer-review manuscript detailing the invention has been submitted to Science.
Related Papers and Patents:
1. Luo, Y., Abidian, M.R., et al., Technology roadmap for flexible sensors. ACS Nano, 17(6), 5211-5295 (2023). https://pubs.acs.org/doi/10.1021/acsnano.2c12606
2. Zhao, Y., Wang, B., Tan, J., Yin, H., Huang, R., Zhu, J., Lin, S., Zhou, Y., Jelinek, D., Sun, Z. and Youssef, K., Voisin, L., Horrillo, A., Zhang, K., Wu, B.M., Coller, H.A., Pei, Q., Emaminejad, S., Soft strain-insensitive bioelectronics featuring brittle materials. Science, 378(6625), 1222-1227 (2022). DOI: 10.1126/science.abn5142
Reference:
UCLA Case No. 2024-108
Lead Inventor:
Qibing Pei, Anne Andrews