X‐ray detectors are widely utilized in medical diagnostics and nondestructive product inspection. Halide perovskites are recently demonstrated as excellent candidates for direct X‐ray detection. However, it is still challenging to obtain high quality perovskites with millimeter‐thick over a large area for high performance, stable X‐ray detectors. Here, methylammonium bismuth iodide (MA3Bi2I9) polycrystalline pellets (PPs) are developed by a robust, cost effective, and scalable cold isostatic‐pressing for fabricating X‐ray detectors with low limit of detection (LoD) and superior operational stability. The MA3Bi2I9‐PPs possess a high resistivity of 2.28 × 1011 Ω cm and low dark carrier concentration of ≈107 cm−3, and balanced mobility of ≈2 cm2 V−1 s−1 for electrons and holes. These merits enable a sensitivity of 563 μC Gyair−1 cm−2, a detection efficiency of 28.8%, and an LoD of 9.3 nGyair s−1 for MA3Bi2I9‐PPs detectors, and the LoD is much lower than the dose rate required for X‐ray diagnostics used currently (5.5 μGyair s−1). In addition, the MA3Bi2I9‐PPs detectors work stably under high working bias field up to 2000 V cm−1 after sensing an integrated dose >320 Gyair with continuous X‐ray radiation, demonstrating its competitive advantage in practical application. These findings provide an approach to explore a new generation of low LoD, stable and green X‐ray detectors based on MA3Bi2I9‐PPs.

SummaryUltrasound brain stimulation is a promising modality for probing brain function and treating brain disease non-invasively and with high spatiotemporal resolution. However, the mechanism underlying its effects remains unclear. Here, we examine the role that the mouse piezo-type mechanosensitive ion channel component 1 (Piezo1) plays in mediating the in vitro effects of ultrasound in mouse primary cortical neurons and a neuronal cell line. We show that ultrasound alone could activate heterologous and endogenous Piezo1, initiating calcium influx and increased nuclear c-Fos expression in primary neurons but not when pre-treated with a Piezo1 inhibitor. We also found that ultrasound significantly increased the expression of the important proteins phospho-CaMKII, phospho-CREB, and c-Fos in a neuronal cell line, but Piezo1 knockdown significantly reduced this effect. Our findings demonstrate that the activity of mechanosensitive ion channels such as Piezo1 stimulated by ultrasound is an important contributor to its ability to stimulate cells in vitro.

Ultrasonic driven wireless charging technology has recently attracted much attention in the next generation bio-implantable systems; however, most developed ultrasonic energy harvesters are bulky and rigid and cannot be applied to general complex surfaces. Here, a flexible piezoelectric ultrasonic energy harvester (PUEH) array was designed and fabricated by integrating a large number of piezoelectric active elements with multilayered flexible electrodes in an elastomer membrane. The developed flexible PUEH device can be driven by the ultrasonic wave to produce continuous voltage and current outputs on both planar and curved surfaces, reaching output signals of more than 2 Vpp and 4 μA, respectively. Potential applications of using the flexible PUEH to charge energy-storage devices and power commercial electronics were demonstrated. Its low attenuation performance was also evaluated using the in vitro test of transmitting power through pork tissue, demonstrating its potential use in the next generation of wirelessly powered bioimplantable micro-devices.

Highlights d MscL-G22S expression efficiently sensitized cells to ultrasound stimulation d Non-invasive ultrasound triggered neural activation in MscLexpressing regions d Ultrasound targeted at the cortical M1 region with MscL evoked rapid EMG responses d Ultrasound successfully activated MscL-expressing neurons in the deeper DMS region

The poor attenuation capability of high-energy X-ray photons hinders the application of X-ray detectors in medical and astrophysical areas. Halide-based perovskites are promising candidates for X-ray detection because of their improved sensitivity. However, their inferior attenuation coefficient is still unsatisfactory for broadband X-ray detection. Here, a new kind of X-ray detection material, AgBi2I7 rudorffite single crystal (SC), is prepared and applied in X-ray detection for the first time, and it shows a higher attenuation coefficient than halide-based perovskites, commercialized a-Se, and the currently outstanding Cd0.9Zn0.1Te (CZT). The AgBi2I7 rudorffite SCs possess outstanding electric properties and excellent stability. AgBi2I7-SC detectors demonstrate a limit of detection (LoD) of 72 nGyair s–1 and a sensitivity of 282.5 μC Gyair –1cm–2 to X-rays and show only a slight performance degradation after ontinuous X-ray irradiation with a total dose of 58 Gyair. This work opens up a new perspective and broad opportunities for halide rudorffite in X-ray detection.