Balloon catheter-based techniques that apply mechanical force to blood vessel walls have dramatically advanced the standard of care for patients with vascular disease. But balloons are limited in their therapeutic potential because they rely on mechanics alone and lack electronically active materials. Recent advances in balloon catheters with integrated electrodes have offered additional treatment capabilities through the application of both mechanical contact force and radio frequency electromotive force. However, these smart balloons remain limited in their mechanics and their ability to provide diagnostic information about local vessel hemodynamics and tissue health near treatment zones. Here, we demonstrate a novel instrumented balloon catheter system that contains stretchable electrodes and thermal-based blood flow sensors, providing hemodynamic information, electrical stimulation, and ablation therapy on a single device. This system accommodates high inflation pressure (∼2 atm) and twisting and bending over a broad range of vascular diameters and geometries. Finite element and analytical modeling capture the anisotropic mechanical and thermal properties of the device during cycles of inflation and deflation in a simulated biological environment. Bench-top ablation and in vivo blood flow measurements highlight the utility of this technology for clinical application.

Established classes of high-performance electronics have driven advances in interventional biomedicine. However, the large size, planar geometry and stiff mechanical properties of standard conventional electronics employed in medical devices give rise to important integration challenges with soft biological tissue. Stretchable and flexible biointegrated electronics could improve treatment procedures across a broad range of applications, including cardiac, neural and endovascular therapies. Here we present novel mechanics, materials and integration strategies for this new class of bioelectronics onboard minimally invasive catheter based systems. Co-located arrays of sensors and actuators affixed to cardiac and angioplasty balloon catheters capture new sensory information during ablation procedures, offering physicians the ability to adjust placement and treatment intra-procedurally. New circuit topologies, enabled by stretchable electronics, also overcome long standing challenges associated with transmitting vast amounts of data through narrow catheter lumens, thus allowing for a large number of sensors to be multiplexed for mapping electrophysiological activity with high spatiotemporal resolution and with a minimal number of routing wires. We present representative examples that highlight the clinical significance of soft bio-integrated electronics, along with the mechanics and processes that enable this technology.

To date, nearly all electronic systems have been rigid and inflexible. However, there are many areas such as in biomedical devices in which these rigid electronics are less than ideal and which require new conformable electronic systems. In order to create effective, compact, and complex systems, stretchable interconnects must be designed to overlap one another in multiple layers. The circular strain relief structure described in this paper effectively redistributes the strain to the crest of the horseshoes of the interconnects themselves. Numerical analysis and simulations of the strain relief structures described in this paper indicate that the structures will function indefinitely when stretched up to a 20% elongation. In-situ electromechanical measurements show that the structures are able to withstand elongations of 285% or more before failing. Precise failure mechanisms including straightening of the interconnects and micro-crack formation are documented with images taken during the electromechanical tests.

Introduction: High-resolution mapping catheters could facilitate detailed mapping of complex arrhythmias, such as persistent atrial fibrillation (AF). Detailed map information acquired with a high-resolution catheter could potentially improve the efficacy of ablation. The goal of this study was to test the feasibility of cardiac mapping using a catheter-based conformal high-density (HD) electrode array (16 electrodes/cm2) that significantly enhances spatial mapping resolution relative to existing devices. Methods: In vivo studies of the catheter-based HD electrode arrays were performed in 4 swine. The HD array was embedded in the balloon and was used to measure atrial electrical activity during both sinus rhythm (SR) and pacing-induced AF. Signal fidelity was evaluated during maneuvers of the catheter in the atria. Results: Activation patterns were identified and propagation speeds were characterized during sinus rhythm and pacing-induced AF. These HD recordings were then used to generate iso-potential conduction maps (Figure). Conclusions: Electrogram measurement with the HD conformal electrode array was feasible, and enabled fine spatio-temporal mapping of the atria during SR and AF, and has the potential to help better define the arrhythmogenic substrate(s) of complex arrhythmias.