Session: 04-25-01: Thin-Film Materials/Electronics for Advanced Biochemical and Biophysical Sensing

Paper Number: 147262

147262 - Wireless, Multimodal Mapping of Organ Health Using a 3d-Printed, Barbed Flexible Microneedle Array 

Introduction: Continuous monitoring of organ function throughout the surgical period, from intraoperative assessment to postoperative recovery, is paramount for optimal patient outcomes. Direct monitoring of organ physiology and biochemistry during surgery allows for early detection of potential complications, such as ischemia, nerve injury, and organ dysfunction, that may arise from non-optimal anesthesia and unintended instrumental damage. On the other hand, postoperative monitoring is a crucial aspect of patient recovery, because multiple serious complications, such as infection, hemorrhage, and graft rejection, can result in significant morbidity and mortality. Conventional blood tests or imaging techniques lack specificity, show delayed responsiveness to local organ conditions, and/or can only be conducted intermittently, failing to inform timely and targeted intervention.

Here we report a wireless implant integrated with a flexible microneedle sensor array that conformationally adhere to organs for continuous monitoring of organ physiology and biochemistry in intra- and post-operative settings. The microneedle sensor array features individual addressability and precisely patterned coatings on each microneedle that allow for multimodal monitoring and/or multisite mapping of various parameters of interest, including metabolites (e.g., sodium, potassium, pH, glucose, lactic acid, uric acid), electrophysiology (e.g., electromyography, EMG), and hemodynamics (e.g., oxygenation). Unlike conventional microneedle arrays that are not individually addressable, precisely functionalized, and flexible for interfacing with tissue, the microneedle sensor array reported here overcome these limitations through 3D-printed microneedles and serpentine interconnects transferred printed to a silicone thin film to offer flexibility and stretchability, followed by selective Parylene coating to expose the microneedle tips for localized precision sensing. This microneedle array also features backward-facing barbs for enhancing tissue adhesion fabricated, which is not possible by conventional 3D printing.

Preliminary results: We fabricated a 6*6 microneedle sensor array (area: 1 cm*1 cm) on a silicone thin film with barb structures. Microneedles with different numbers of rows of backward-facing barbs were fabricated using a deterministic deformation process. The microneedle sensor array were electrodeposited with gold nanoparticles and PEDOT:PSS, followed by subsequent coating with various sensing agents to allow for specific detection of various biochemicals and physiological parameters (e.g., EMG and oxygenation). After in vitro characterization, we implanted a microneedle sensor array that conformationally adhered to the kidney of a rat for multimodal monitoring. We achieved concurrent sensing of lactic acid, uric acid, and tissue oxygenation. Our results indicate that simulated ischemia caused fluctuation of tissue oxygenation in the kidney, accompanied by accumulation of lactic acid and uric acid.

Conclusion: This study presents a novel wireless implant with a microneedle sensor array for continuous and multimodal monitoring of organ health during surgery and recovery. This microneedle array offers unique advantages over conventional options through individually addressable sensors, precise functionalization, and conformable design for intimate tissue adhesion.  Our preliminary in vitro and in vivo results demonstrate the capability for concurrent sensing of metabolites, electrophysiology, and hemodynamics, paving the way for a new generation of monitoring tools to improve patient outcomes.

Presenting Author: Wei Ouyang Dartmouth College

Presenting Author Biography: Wei Ouyang is currently an Assistant Professor of ECE/BME at Dartmouth College. His research focuses on developing bio-integrated microsystems for neuroscience and healthcare innovation, with a focus on MEMS, wearables, and implantables. Prior to joining the Dartmouth faculty, he completed a postdoctoral fellowship with Prof. John A. Rogers in the Querrey Simpson Institute for Bioelectronics at Northwestern University. He received his BS in microelectronics from Peking University, China, and both his SM degree in electrical engineering and computer science and his PhD in electrical engineering from the Massachusetts Institute of Technology (MIT) under the supervision of Prof. Jongyoon Han.

Authors:

Xiangling Li Dartmouth College
Shibo Liu Dartmouth College
Wei Ouyang Dartmouth College