Session: Government Agency Student Posters

Paper Number: 173006

A Soft Multimodal Optoelectronic Array Interface for Multiparametric Mapping of Heart Function in Vivo 

Multiparametric investigation of cardiac physiology is crucial for the diagnosis and therapy of heart disease. However, no method exists to simultaneously map multiple parameters that govern cardiac (patho)physiology from beating hearts in vivo. Here, we present a cardiac sensing platform that addresses this challenge, functioning with a wireless interface. This platform offers potential widespread use in cardiac research to support scientific discoveries and advance clinical lifesaving diagnostics and therapies.

Advanced fabrication and assembling strategies enable the heterogeneous integration of transparent microelectrodes, light emitting diodes, photodiodes, and optical filters into a multilayer array structure on soft substrates. The microelectrodes exhibit superior electrochemical performance for measuring electrical potentials and excellent transparency for co-localized fluorescence measurement. The device shows excellent biocompatibility and records the fluorescence of calcium reporter with performance comparable to imaging cameras. Multiparametric in vivo mapping of electrical excitation, calcium dynamics, and their combined effects on cardiac excitation-contraction coupling is demonstrated during normal rhythm, arrhythmia, and treatment.

The fabrication of the optoelectronic array began with laminating a 25 μm PET film onto a glass carrier using PDMS adhesive. A 7-μm SU-8 planarization layer was spin-coated onto the PET. Interconnects for μ-LEDs and μ-PDs were patterned via electron beam evaporation through a custom stainless steel shadow mask to deposit Cr/Cu. μ-PDs and μ-LEDs were flip-chip soldered onto the interconnects using Indalloy 4 and SAC305 pastes. An SU-8-based optical filter with 2.5 wt% narrowband absorber was patterned over the μ-PDs. A 100-μm SU-8 layer encapsulated the subsystem, and another 2-μm SU-8 layer defined the MEA pattern. Ag nanowires were spin-coated, and the electrodes were defined via photolithography and SU-8 lift-off. Electroplating deposited Au shells of varying thicknesses (0.1 mA/cm², 60°C, 1 hr) onto Ag NWs. Devices were laser-cut and delaminated to complete fabrication.

The wireless circuit, designed in Autodesk EAGLE and manufactured externally, incorporated analog front ends, ADCs, μCUs, and a Bluetooth module for wireless data transmission and LED control. Optical, electrical, and electrochemical properties were characterized using a UV-vis-NIR spectrophotometer, source meter, quantum efficiency system, and potentiostat. Impedance was measured using a three-electrode configuration in PBS. Mechanical durability was tested via cyclic bending at 5 mm radius, and temperature rise was evaluated with infrared imaging. ICP-MS assessed Ag leaching. Ex vivo and in vivo mapping experiments used Langendorff-perfused and ventilated GCaMP6f mouse models, respectively, with device placement on the LV. Data were recorded via Intan RHS systems and analyzed using MATLAB.

The soft multimodal device integrates a 2×2 array of Au-Ag nanowire microelectrodes aligned with blue μ-LEDs and μ-PDs with optical filters. The Au-Ag NWs showed tunable electrochemical impedance and optical transparency by varying the Au shell thickness. Au-Ag NW-10 (10 nm Au) microelectrodes demonstrated low 1-kHz impedance (7.0 ± 0.14 kΩ) and >80% optical transmittance, making them ideal for co-localized electrophysiological and fluorescence recordings. Optical filters blocked blue excitation light while enabling selective detection of GCaMP6f green fluorescence, with μ-PD/μ-LED channels showing a wavelength selectivity >1400. The device exhibited mechanical stability over 4000 bending cycles and minimal thermal rise (< 0.6°C), confirming suitability for in vivo cardiac mapping. Wireless measurements confirmed stable signal quality for both electrical and calcium fluorescence modalities.

Ex vivo experiments on Langendorff-perfused GCaMP6f mouse hearts validated device performance against CMOS optical mapping. The device reliably measured electrograms and calcium transients with comparable APD80, CaTD80, rise times, and voltage-calcium delays. In vivo, the device mapped spatial and temporal propagation of electrical and calcium waves during pacing, sinus rhythm, and AV block, highlighting the ability to track excitation-contraction coupling and uncoupling in dynamic physiological conditions. Pharmacological tests with verapamil and pinacidil further demonstrated the device’s ability to detect drug-induced changes in calcium handling and electrophysiology.

This platform enables simultaneous, localized, multiparametric mapping of heart function in vivo, providing insights not achievable with current techniques. Future directions include scaling channel counts, integrating other functional reporters, and enabling chronic, untethered operation for disease modeling and therapeutic evaluation.

Presenting Author: Nathaniel Quirion The George Washington University

Presenting Author Biography: Nathaniel Quirion is a Ph.D. candidate in Biomedical Engineering at George Washington University. He specializes in the development of implantable optoelectronic systems for high-fidelity electrophysiological recording and stimulation. His interdisciplinary work integrates micro/nanofabrication, materials science, semiconductor device engineering, and biosignal processing to advance next-generation neural and cardiac interface technologies.

His technical portfolio includes expertise in photolithography, thin-film deposition, polymer microstructures, and soft-material integration for flexible electronics. His ongoing research focuses on scaling these systems to enable dye-free optical sensing and developing wireless, chronically implantable platforms for real-time physiological monitoring.

Driven by a passion for translational impact, he collaborates closely with clinical researchers to bridge the gap between device innovation and biomedical application. He is also an experienced mentor and educator, leading undergraduate research projects and outreach initiatives through NIH-supported programs.

Outside the lab, Nathaniel is committed to personal growth and strives to embody a balance of intellectual rigor, kindness, and creativity. With an eye toward scientific excellence and human-centered design, he aims to shape technologies that enhance human health meaningfully.

Authors:

Nathaniel Quirion The George Washington University
Luyao Lu The George Washington University