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Biodegradable Electronic Materials for Biomedical Applications

Description:

OBJECTIVE: Identify and develop a set of biodegradable materials and industry-compatible fabrication processes for demonstrating fully biodegradable, biomedical sensor/actuator systems with electronic performance comparable to SOI-based systems. Demonstrate ability to spatio-temporally control electrical function for therapeutic applications such as surgical site infection (SSI) mitigation and nerve stimulation for chronic pain relief. DESCRIPTION: Electronically active biomedical systems that can harmlessly and controllably resorb into the body open new avenues to therapeutic applications that are currently unfeasible. Those of specific interest to DARPA and the DoD include continuous in vivo monitoring with external, wireless power and receivers (e.g. for prosthetic fit or bone fractures), appliques that combat broad-spectrum surgical site infections (SSI) without antibiotics (e.g. for wound healing or medical implants), electrical stimulation-based modalities to combat chronic pain without opioids, or electrical simulation for regenerative applications. Furthermore, in limited resource areas such as DoD deployment locations, remote or impoverished geographic areas, or emergency response locations where clinical care is limited, biodegradable biomedical devices would enable remote patient monitoring, compliance, and treatment and would negate the need for device extraction. However, these applications are currently untenable because the materials space fails to resolve key technical challenges to implementation. Current approaches to biodegradable, biocompatible sensor/actuator systems for medical therapeutics and monitoring provide limited utility and poor performance for two key technological reasons. 1. Demonstrations that utilize biodegradable organic/polymer-based active regions to produce the electrical function, lack the electronic performance (e.g. carrier mobility, , typically ~0.1-1 cm2/V-s) to be of significant utility beyond low power transistors. 2. Other examples segregate the biodegradable function to the non-electronically active components while leaving behind non-degradable elements (where biocompatibility is an issue) that require future extraction. The extraction costs related to patient care, morbidity, and mortality, and additional risks associated with surgical site infections and antibiotic-resistant strains (and their combined danger) make additional device extraction undesirable; however allowing the device to persist inflicts unnecessary burden on the patient and potential future complications. Potential avenues to successful development of the aforementioned applications all require the identification, development, and optimization of electronic materials with performance amenable to simple low power systems with onboard processing (e.g semiconductor active regions with electron mobility, n, ~102 cm2/V-s). Critically, all materials under development must be biocompatible and bioresorbable. Devices developed under this SBIR must demonstrate stable functionality over medically-relevant timescales (e.g. 15 days for an SSI treatment applique) and controllable bioresorption over medically-appropriate timescales (e.g. hours to weeks, depending on the material constituents). Devices developed must operate with electronic performance applicable to the purported treatment (e.g. blood pH monitoring with data transfer to external receiver at 10 minute intervals). This topic is focused on the development of a class of biodegradable materials capable of electronic functionality comparable to traditional electronics used in low power, low cost systems. The biocompatible materials used in these systems should be optimized for functionality, performance, and tunable bioresorption timescales. Proposers should develop the materials, device designs, and manufacturing approaches. Mechanisms for power and data extraction should be described, as well as a plan for developing a fabrication process compatible with the good manufacturing practice (GMP) platform. Although the (ultimately) necessary animal model testing is not specifically funded under this solicitation, proposers should also develop and present a regulatory approval plan for successful materials classes. PHASE I: Briefly describes expectations and desired results/end product for Phase I, 6-month feasibility study, $100K (max) effort. Demonstrate through analysis and proof-of-concept experiments the feasibility of a fully biodegradable, biocompatible electronic sensor and actuator technology for a DoD-relevant biomedical application (as discussed above). The solution should provide not only functionality in this application context, but with a set of components that are sufficiently general in their operation that they can be re-purposed for other related applications in biomedical electronics. The deliverable will be a paper study with detailed material and device analysis, together with experiments to illustrate high performance capabilities (i.e. comparable to SOI-based systems) in the key components. Mechanisms for power and data extraction should be described. Additionally, the study should include an overview and analysis of a strategy for scalable and industry-compatible fabrication processes for device production. The Technology Readiness Level (TRL) at the end of Phase I should be between 3 and 4. PHASE II: Briefly describes expectations and minimum required deliverable for Phase II, 2-year major R & D effort, culminating in a well-defined deliverable prototype, $1M (max) effort. Develop, test, and demonstrate a set of biodegradable, biocompatible materials that exhibit controllable degradation rates and electronic functionality comparable to traditional electronics used in low power, low cost devices. Construct and demonstrate the operation of an integrated prototype device capable of achieving the objective goals as described above. Demonstrate stable functionality over medically-relevant timescales (e.g. 15 days for an SSI treatment applique) and controllable bioresorption over medically-safe timescales (e.g. days to months, depending on the application). Devices developed must demonstrate electronic performance applicable to the purported treatment, along with mechanisms for onboard power, processing, and data transmission. Assess the properties of the electronics and the actuators, with quantitative comparison to computational models. Deliverables of a prototype device and valid test data appropriate for a commercial production path are expected, as well as a demonstration of functionality in vitro. Experiments should be conducted using biospecimens and/or models appropriate for the application. Provide a detailed plan of the animal model experiments to be completed during Phase III (e.g. adsorption, distribution, metabolism, and excretion of the resorbed components, toxicity) required for regulatory approval. Establish roadmaps to commercial products, including manufacturing and regulatory considerations. The Technology Readiness Level (TRL) at the end of Phase II should be 5. PHASE III: The technology to be developed is applicable to numerous biomedical devices for the DoD and military: enhanced wound healing and monitoring (including prosthetic fit and bone fractures), appliques that combat broad-spectrum surgical site infections (SSI) without antibiotics for wound healing or medical implants, electrical stimulation-based modalities to combat chronic pain without opioids, and electrical stimulation for regenerative applications. Potential transition customers include Military Health System Defense Medical Research and Development Program (MHS DMRDP), United States Army Institute of Surgical Research (USAISR), Armed Forces Institute of Regenerative Medicine (AFIRM), Military Infectious Diseases Research Program (MIDRP), and Defense Threat Reduction Agency (DTRA). The technology to be developed is applicable to biomedical devices and active scaffolds for therapeutic treatment applications as well as monitoring, diagnosis and performance measurements. There is a significant commercial market for biodegradable, medical devices and active scaffolds, particularly those currently involved in the development of technologies capable of enhancing and monitoring wound and bone fracture healing, pain relief without opioids, drug delivery, performance monitoring, and the continuous monitoring of glucose and other metabolites. The developed technology would allow improvement of existing medical devices and expansion of devices and modalities for therapeutic treatment and monitoring of additional health conditions. REFERENCES: 1) A microfabricated wireless RF pressure sensor made completely of biodegradable materials, Solid-State Sensors, Actuators, and Microsystems Workshop, Hilton Head Island, South Carolina, June 3-7, 2012. 2) Dissolvable films of silk fibroin for ultrathin conformal bio-integrated electronics, Nature Materials 9, 511517 (2010). 3) Biomaterials-based organic electronic devices, Polymer International 59, 563-267 (2010). 4) Manufacturing and commercialization issues in organic electronics, Journal of Materials Research 19, 1974-1989 (2004). 5) Organic thin film transistors fabricated on resorbable biomaterial substrates, Advanced Materials 22, 651-655 (2010). 6) Silicon electronics on silk as a path to bioresorbable, implantable devices, Applied Physics Letters 95, 133701 (2009). 7) Biodegradable electronics, A desirable solution, The Economist, http://www.economist.com/node/16837947, 17 August 2010.8) Brief electrical stimulation promotes the speed and accuracy of motor axonal regeneration, The Journal of Neuroscience 20, 2602-2608 (2000).
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