A remarkable feature of modern silicon electronics is its ability to remain functionally and physically invariant, almost indefinitely for many practical purposes. Here, we introduce a silicon-based technology that offers the opposite behavior: it gradually vanishes over time, in a well-controlled, programmed manner. Devices that are ‘transient’ in this sense create application possibilities that cannot be addressed with conventional electronics, such as active implants that exist for medically useful timeframes, but then completely dissolve and disappear via resorption by the body. We report a comprehensive set of materials, manufacturing schemes, device components and theoretical design tools for a complementary metal oxide semiconductor (CMOS) electronics of this type, together with four different classes of sensors and actuators in addressable arrays, two options for power supply and a wireless control strategy. A transient silicon device capable of delivering thermal therapy in an implantable mode and its demonstration in animal models illustrate a system-level example of this technology.

Capabilities in health monitoring via capture and quantitative chemical analysis of sweat could complement, or potentially obviate the need for, approaches based on sporadic assessment of blood samples. Established sweat monitoring technologies use simple fabric swatches and are limited to basic analysis in controlled laboratory or hospital settings. We present a collection of materials and device designs for soft, flexible and stretchable microfluidic systems, including embodiments that integrate wireless communication electronics, which can intimately and robustly bond to the surface of skin without chemical and mechanical irritation. This integration defines access points for a small set of sweat glands such that perspiration spontaneously initiates routing of sweat through a microfluidic network and set of reservoirs. Embedded chemical analyses respond in colorimetric fashion to markers such as chloride and hydronium ions, glucose and lactate. Wireless interfaces to digital image capture hardware serve as a means for quantitation. Human studies demonstrated the functionality of this microfluidic device during fitness cycling in a controlled environment and during long-distance bicycle racing in arid, outdoor conditions. The results include quantitative values for sweat rate, total sweat loss, pH and concentration of both chloride and lactate.

Here, we report advanced materials and devices that enable highefficiency mechanical-to-electrical energy conversion from the natural contractile and relaxation motions of the heart, lung, and diaphragm, demonstrated in several different animal models, each of which has organs with sizes that approach human scales. A cointegrated collection of such energy-harvesting elements with rectifiers and microbatteries provides an entire flexible system, capable of viable integration with the beating heart via medical sutures and operation with efficiencies of ∼2%. Additional experiments, computational models, and results in multilayer configurations capture the key behaviors, illuminate essential design aspects, and offer sufficient power outputs for operation of pacemakers, with or without battery assist.biomedical implants | flexible electronics | transfer printing | wearable electronics | heterogeneous integration N early all classes of active wearable and implantable biomedical devices rely on some form of battery power for operation. Heart rate monitors, pacemakers, implantable cardioverterdefibrillators, and neural stimulators together represent a broad subset of bioelectronic devices that provide continuous diagnostics and therapy in this mode. Although advances in battery technology have led to substantial reductions in overall sizes and increases in storage capacities, operational lifetimes remain limited, rarely exceeding a few days for wearable devices and a few years for implants. Surgical procedures to replace the depleted batteries of implantable devices are thus essential, exposing patients to health risks, heightened morbidity, and even potential mortality. The health burden and costs are substantial, and thus motivate efforts to eliminate batteries altogether, or to extend their lifetimes in a significant way.Investigations into energy-harvesting strategies to replace batteries demonstrate several unusual ways to extract power from chemical, mechanical, electrical, and thermal processes in the human body (1, 2). Examples include use of glucose oxidation (3), electric potentials of the inner ear (4), mechanical movements of limbs, and natural vibrations of internal organs (5-7). Such phenomena provide promising opportunities for power supply to wearable and implantable devices (6-8). A recent example involves a hybrid kinetic device integrated with the heart for applications with pacemakers (7). More speculative approaches, based on analytical models of harvesting from pressure-driven deformations of an artery by magneto-hydrodynamics, also exist (9).Cardiac and lung motions, in particular, serve as inexhaustible sources of energy during the lifespan of a patient. Mechanicalto-electrical transduction mechanisms in piezoelectric materials offer viable routes to energy harvesting in such cases, as demonstrated and analyzed by several groups recently (10-17). For example, proposals exist for devices that convert heartbeat vibrations into electrical energy using resonantly coupled motions of thick (1-2 mm) pi...

Among patients with unstable angina or myocardial infarction without ST-segment elevation, prasugrel did not significantly reduce the frequency of the primary end point, as compared with clopidogrel, and similar risks of bleeding were observed. (Funded by Eli Lilly and Daiichi Sankyo; TRILOGY ACS ClinicalTrials.gov number, NCT00699998.).

Development of advanced surgical tools for minimally invasive procedures represents an activity of central importance to improvements in human health. A key materials challenge is in the realization of bio-compatible interfaces between the classes of semiconductor and sensor technologies that might be most useful in this context and the soft, curvilinear surfaces of the body. This paper describes a solution based on biocompatible materials and devices that integrate directly with the thin elastic membranes of otherwise conventional balloon catheters, to provide multimodal functionality suitable for clinical use. We present sensors for measuring temperature, flow, tactile, optical and electrophysiological data, together with radio frequency (RF) electrodes for controlled, local ablation of tissue. These components connect together in arrayed layouts designed to decouple their operation from large strain deformations associated with deployment and repeated inflation/deflation. Use of such ‘instrumented’ balloon catheter devices in live animal models and in vitro tests illustrates their operation in cardiac ablation therapy. These concepts have the potential for application in surgical systems of the future, not only those based on catheters but also on other platforms, such as surgical gloves.