Devices that perform cardiac mapping and ablation to treat atrial fibrillation provide an effective means of treatment. Current devices, however, have limitations that either require tedious point-by-point mapping of a cardiac chamber or have limited ability to conform to the complex anatomy of a patient’s cardiac chamber. In this work, a detailed, scalable, and manufacturable technique is reported for fabrication of a multielectrode, soft robotic sensor array. These devices exhibit high conformability (~85 to 90%) and are equipped with an array of stretchable electronic sensors for voltage mapping. The form factor of the device is intended to match that of the entire left atrium and has a hydraulically actuated soft robotic structure whose profile facilitates deployment from a 13.5-Fr catheter. We anticipate that the methods described in this paper will serve a new generation of conformable medical devices that leverage the unique characteristics of stretchable electronics and soft robotics.

IntroductionMicro/nanopatterning of surfaces is a powerful technique for engineering of the surface properties of devices or objects Micropatterning provides a powerful means for engineering surface properties, such as friction, adhesion, and biocompatibility, with promise for medical device applications. While soft lithography allows for micropatterning on curved surfaces, there are limitations to the level of curvature and object complexity achievable. A cost effective and simple method is realized for micropatterning complex 3D objects and is demonstrated for a variety of micropatterns, materials, and devices. The technique integrates the simple principles of soft lithography for fabrication of flexible templates, and vacuum bagging, for transfer of the patterns on arbitrary shaped nonplanar objects. The technique is demonstrated with silicones, polyurethanes, and nitinol materials ubiquitous in medical devices, due to their mechanics, biocompatibility, and hemocompatibility. Micropatterns inspired by shark skin riblets and tree frogs are demonstrated. The flexibility of this method is demonstrated by transferring patterns to various objects/devices, including 3D printed objects, soft robotic grippers, guidewires, and balloon catheters.

Micropatterning is often used to engineer the surface properties of objects because it allows the enhancement or modification of specific functionalities without modification of the bulk material properties. Microneedle arrays have been explored in the past for drug delivery and enhancement of tissue anchoring; however, conventional methods are primarily limited to thick, planar substrates. Here, we demonstrate a method for the fabrication of microneedle arrays on thin flexible polyurethane substrates. These thin-film microneedle arrays can be used to fabricate balloons and other inflatable objects. In addition, these thin-filmed microneedles can be transferred, using thermal forming processes, to more complex 3D objects on which it would otherwise be difficult to directly pattern microneedles. This function is especially useful for medical devices, which require effective tissue anchorage but are a challenging target for micropatterning due to their 3D nonplanar shape, large size, and the complexity of the required micropatterns. Ultrathin flexible thermoplastic polyurethane microneedle arrays were fabricated from a polydimethylsiloxane (PDMS) mold. The technique was applied onto the nonplanar surface of rapidly prototyped soft robotic implantable polyurethane devices. We found that a microneedle-patterned surface can increase the anchorage of the device to a tissue by more than twofold. In summary, our soft lithographic patterning method can rapidly and inexpensively generate thin-film microneedle surfaces that can be used to produce balloons or enhance the properties of other 3D objects and devices.