We report a fabrication method for flexible and printable thermal sensors based on composites of semicrystalline acrylate polymers and graphite with a high sensitivity of 20 mK and a high-speed response time of less than 100 ms. These devices exhibit large resistance changes near body temperature under physiological conditions with high repeatability (1,800 times). Device performance is largely unaffected by bending to radii below 700 μm, which allows for conformal application to the surface of living tissue. The sensing temperature can be tuned between 25°C and 50°C, which covers all relevant physiological temperatures. Furthermore, we demonstrate flexible active-matrix thermal sensors which can resolve spatial temperature gradients over a large area. With this flexible ultrasensitive temperature sensor we succeeded in the in vivo measurement of cyclic temperatures changes of 0.1°C in a rat lung during breathing, without interference from constant tissue motion. This result conclusively shows that the lung of a warm-blooded animal maintains surprising temperature stability despite the large difference between core temperature and inhaled air temperature. T emperature control plays a very important role in homeostasis, and body temperature varies both spatially and temporally in an effort to transfer heat between the living body and the environment via skin and respiratory organs. Accurate measurement of localized temperature changes in soft tissue regardless of large-scale motion is important in understanding thermal phenomena of homeostasis and realizing future sophisticated health diagnostics (1-3). Therefore, flexible temperature sensors which softly interface with tissue have been investigated frequently for applications in the medical field. However, these applications require the combination of sensitivity, fast response time, stability in physiological environments, and multipoint measurement. Before this work, to our knowledge, no experiment has simultaneously demonstrated orders-of-magnitude changes in electrical properties (sensitivity) repeatedly at varying physiological temperatures and conditions (stability) in a robust, easy-to-fabricate, flexible temperature sensor (processability).When sensors and electronics are directly attached to the surface of an animal body, the use of soft and flexible electronic devices is expected to reduce mechanical stress induced on the body. From this viewpoint, the field of flexible electronics has attracted much attention recently. The ability to gather information such as pressure and temperature from curvilinear and dynamic surfaces without impairing the movement or usability of the users is unmatched by conventional silicon electronics. There have been reports of the potential application of flexible electrodes on ultrathin substrates (4), flexible sensors that measure biological signals, electrocardiograms, temperature, pressure (5, 6), organic amplifier systems (7), high-sensitivity pressure sensors (8), and ultrathin and imperceptible devices (9, 10).To meas...

The stretchable and active multielectrode array successfully measured electrocardiography of rat during blood exposure.

In vivo electronic monitoring systems are promising technology to obtain biosignals with high spatiotemporal resolution and sensitivity. Here we demonstrate the fabrication of a biocompatible highly conductive gel composite comprising multi-walled carbon nanotube-dispersed sheet with an aqueous hydrogel. This gel composite exhibits admittance of 100 mS cm−2 and maintains high admittance even in a low-frequency range. On implantation into a living hypodermal tissue for 4 weeks, it showed a small foreign-body reaction compared with widely used metal electrodes. Capitalizing on the multi-functional gel composite, we fabricated an ultrathin and mechanically flexible organic active matrix amplifier on a 1.2-μm-thick polyethylene-naphthalate film to amplify (amplification factor: ∼200) weak biosignals. The composite was integrated to the amplifier to realize a direct lead epicardial electrocardiography that is easily spread over an uneven heart tissue.

Summary The eradication of Helicobacter pylori often leads to platelet recovery in patients with chronic idiopathic thrombocytopenic purpura (cITP). Although this clinical observation suggests the involvement of H. pylori, little is known about the pathogenesis of cITP. We initially examined the effect of H. pylori eradication on platelet counts in 20 adult Japanese cITP patients. Then, using platelet eluates as the probe in immunoblot analyses, we examined the role of molecular mimicry in the pathogenesis of cITP. Helicobacter pylori infection was detected in 75% (15 of 20) of cITP patients. Eradication was achieved in 13 (87%) of the H. pylori‐positive patients, seven (54%) of which showed increased platelet counts within the 4 months following treatment. Completely responsive patients also showed significant declines in platelet‐associated immunoglobulin G (PAIgG) levels. Platelet eluates from 12 (nine H. pylori‐positive and three H. pylori‐negative) patients recognized H. pylori cytotoxin‐associated gene A (CagA) protein, and in three completely responsive patients, levels of anti‐CagA antibody in platelet eluates declined after eradication therapy. Cross‐reactivity between PAIgG and H. pylori CagA protein suggests that molecular mimicry by CagA plays a key role in the pathogenesis of a subset of cITP patients.

A unique form of adaptive electronics is demonstrated, which change their mechanical properties from rigid and planar to soft and compliant, in order to enable soft and conformal wrapping around 3D objects, including biological tissue. These devices feature excellent mechanical robustness and maintain initial electrical properties even after changing shape and stiffness.