We report classes of electronic systems that achieve thicknesses, effective elastic moduli, bending stiffnesses, and areal mass densities matched to the epidermis. Unlike traditional wafer-based technologies, laminating such devices onto the skin leads to conformal contact and adequate adhesion based on van der Waals interactions alone, in a manner that is mechanically invisible to the user. We describe systems incorporating electrophysiological, temperature, and strain sensors, as well as transistors, light-emitting diodes, photodetectors, radio frequency inductors, capacitors, oscillators, and rectifying diodes. Solar cells and wireless coils provide options for power supply. We used this type of technology to measure electrical activity produced by the heart, brain, and skeletal muscles and show that the resulting data contain sufficient information for an unusual type of computer game controller.

Curved surfaces, complex geometries, and time-dynamic deformations of the heart create challenges in establishing intimate, nonconstraining interfaces between cardiac structures and medical devices or surgical tools, particularly over large areas. We constructed large area designs for diagnostic and therapeutic stretchable sensor and actuator webs that conformally wrap the epicardium, establishing robust contact without sutures, mechanical fixtures, tapes, or surgical adhesives. These multifunctional web devices exploit open, mesh layouts and mount on thin, bio-resorbable sheets of silk to facilitate handling in a way that yields, after dissolution, exceptionally low mechanical moduli and thicknesses. In vivo studies in rabbit and pig animal models demonstrate the effectiveness of these device webs for measuring and spatially mapping temperature, electrophysiological signals, strain, and physical contact in sheet and balloon-based systems that also have the potential to deliver energy to perform localized tissue ablation.flexible electronics | semiconductor nanomaterials | stretchable electronics | implantable biomedical devices | cardiac electrophysiology C ardiac arrhythmias occur in all component structures and 3D regions of the heart, resulting in significant challenges in diagnosis and treatment of precise anatomic targets (1). Many common arrhythmias, including atrial fibrillation and ventricular tachycardia, originate in endocardial substrates and then propagate in the transverse direction to affect epicardial regions (1, 2). Characterizing arrhythmogenic activity at specific regions of the heart is thus critical for establishing the basis for definitive therapies such as cardiac ablation (3). Advanced tools that offer sufficient spatial resolution (<1 mm) and intimate mechanical coupling with myocardial tissue, but without undue constraints on natural motions, would therefore be of great clinical importance (4-6). To date, cardiac ablation procedures have largely relied on point ablation catheters deployed in the endocardial space (1, 5, 7-9). Although successful in the treatment of simple arrhythmias originating in and around the pulmonary veins, these devices are poorly suited for treating complex arrhythmias, such as persistent atrial fibrillation (10-13), that arise from various sites inside the left atrium. Other classes of devices have demonstrated the utility of spatiotemporal voltage mapping using various modes of operation, including noninvasive surface mapping designs (14, 15), epicardial voltage-mapping "socks" (16-20), and endocardial contact and noncontact catheters, with densities approaching 64 electrodes (21-31). These solutions all exploit arrays of passive metal wirebased electrodes integrated on wearable vests and socks (14-20) or catheter systems (21-26) for mapping of complex arrhythmias. Building such mesh structures requires manual assembly and is only possible because the individual wires are millimeter scale in diameter and thus sufficiently large to be threaded to form a mesh.Fo...

Sutures are among the simplest and most widely used devices in clinical medicine. All existing synthetic and natural forms use thread-like geometries, as purely passive, mechanical structures that are fl exible and resilient to tensile stress. Several recent reports describe strategies to incorporate advanced functionality into this platform through the employment of shape-memory polymers that offer mechanical actuation or through the release of bioresorbable compounds that carry growth factors and antibiotics to accelerate healing. [1][2][3] Such technologies lack, however, programmable actuation or sensory feedback control. Sutures that embed fl exible sensors and associated electronic circuits could perform these and other related functions. Demonstrations using thin fl exible strips equipped with sensors for pressure and chemical monitoring have been reported [ 4 , 5 ] but not in designs for use as sutures. Furthermore, the organic and silver-based material components comprising these devices might limit their performance capabilities, and also lead to concerns about longterm durability in moist, dynamic conditions in the body. Here, we report strips with signifi cantly smaller form factors, specifi cally engineered for use as fl exible sutures ( ∼ 1 mm width and ∼ 3 μ m thickness) 'instrumented' with high quality single crystal inorganic semiconductors of biocompatible materials such as silicon in nanomembrane formats. [ 6 ] The resulting class of technology offers routes to high levels of performance and sophisticated function in sensors and actuators suitable for in vivo use. This new type of diagnostic/therapeutic tools could monitor, sense and actuate in a manner coordinated with natural biological responses in the body for improved health outcomes.The systems described in the following use ultrathin, narrow strips of biocompatible polymers as platforms for integrated single crystal silicon nanomembranes (Si NM) electronics and sensors, confi gured together in ways that provide requisite mechanical properties. The examples focus on measurement and delivery of heat, using systems composed of Si NMs, multicomponent metallization and dielectric interlayers/encapsulants, all in bifacial designs (i.e. devices and interconnects on both sides of a thin substrate). The collective properties, including operational compatibility with complete immersion in water and biofl uids [ 7 ] and robustness to large stresses/strains that occur during suturing, are demonstrated through in vivo evaluations using animal models. The envisioned clinical context is for sensing and programmable delivery of local heating and electrical stimulation to promote healing of chronic wounds [ 8 , 9 ] or for heat shock strategies in cancer treatment. [ 10 ] Additional possibilities exist in thermally activated drug release from temperature sensitive, polymer host matrices as coatings onto these devices. [ 11 ] A representative system includes Si NM diode temperature sensors and microscale Joule heating elements

Scalable and cost-effective protocols to pattern and integrate colloidal quantum dots (QDs) with high resolution have been challenging to establish. While their solubility can facilitate certain processes such as spin-casting into thin films, it also makes them incompatible with many conventional patterning techniques including photolithography that require solution processing. In this work, we present “photoresist (PR) contact patterning”, a dry means to pattern QD films over large areas with high resolution while maintaining desired properties. Here, a PR layer on an elastomer substrate is patterned by conventional photolithography and used as a dry contact stamp to selectively peel off QDs in the contact regions, leaving behind a QD film with the negative of the PR pattern. Once patterned, QD films are readily transferred and integrated on foreign substrates by subsequent transfer printing processes. Patterned PR layers can also be transferred from elastomer substrates onto QD films and used as masking layers for subsequent deposition and patterning of additional materials, e.g., patterned metal electrodes or charge transport layers for QD-based devices. The study of the interfacial mechanics and energy of materials associated with PR contact patterning reveals why a lithographically patterned PR is superior for high-resolution QD film patterning. Applicability of PR contact patterning is demonstrated through the fabrication of red, green, and blue (RGB) QD light-emitting diode pixels. PR contact patterning presented in this work not only allows dry patterning of QD films but also enables high-resolution integration of functional multistack structures for future QD-based electronic and optoelectronic devices.

We present a micromanufacturing method for constructing microsystems, which we term 'micro-masonry' based on individual manipulation, influenced by strategies for deterministic materials assembly using advanced forms of transfer printing. Analogous to masonry in construction sites, micro-masonry consists of the preparation, manipulation, and binding of microscale units to assemble microcomponents and microsystems. In this paper, for the purpose of demonstration, we used microtipped elastomeric stamps as manipulators and built three dimensional silicon microstructures. Silicon units of varied shapes were fabricated in a suspended format on donors, retrieved, delivered, and placed on a target location on a receiver using microtipped stamps. Annealing of the assembled silicon units permanently bound them and completed the micro-masonry procedure.