Lead halide perovskites (LHPs) have been widely investigated in photodetection applications owing to their intriguing optoelectronic properties. However, the application of LHPs-based photodetectors (PDs) is hindered because of the toxicity of lead and instability in ambient air. Here, an air-stable selfpowered photodetector is designed based on all-inorganic lead-free CsBi 3 I 10 / SnO 2 heterojunction. The device exhibits broad spectral response in both UV and visible light, fast response on µs scale, and decent long-term stability. The device holds a faster response speed (t r /t d = 7.8/8.8 µs), among the best reported self-powered lead-free perovskites photodetectors. More importantly, the device can display obvious photoresponses even under ultra-weak light intensity as low as 10 pW cm -2 , showing better weak-light sensitivity than previously reported lead-free perovskites photodetectors, to the best of our knowledge. Moreover, the device holds good air stability in the 73 days test without encapsulation. These results suggest that CsBi 3 I 10 /SnO 2 -based self-powered PDs with high photodetection capability possess enormous potential in stable and broadband PDs for weak light detection in the future.

Electronic sensors for human body health and activity monitoring applications still face challenges, such as nonbiodegradability and high production costs. As a kind of electronic device with noncontact characteristics, humidity sensors are playing an increasingly important role in monitoring human health. In this work, the humidity sensors were prepared by depositing edible sodium carboxymethyl cellulose (CMC) ink on a biodegradable substrate polylactic acid (PLA) via an inkjet printing technology, which not only effectively reduces the risk of pollution to the human body but also greatly reduces the production costs. The humidity sensor based on CMC has ultrahigh sensitivity (56424%), short response time (0.5 s), good cyclic stability, and exhibits excellent performances in real-time monitoring applications for human breathing and noncontact fingertip movement. Therefore, our research will contribute to the large-scale preparation of high-performance, environmental friendly, and low-cost humidity sensors, and the development of monitoring technology in human health.

Ecofriendly and biofriendly materials are highly appealing in electronic devices with the booming development of the Internet of Things. Humidity sensors perform an indispensable role in various fields such as monitoring industry processes and living systems. In this contribution, for the first time, edible and abundant material-flour has been introduced to the sensing layers for humidity detection. The ionic conductive K 2 CO 3 and hygroscopic glycerol (Gly) with biosafety were introduced to the sensing layer to promote a humidity sensing capability and longtime stability. The ingestible Gly-K 2 CO 3 flour-based humidity sensor using PLA as substrates displays an excellent sensing performance and wide humidity detecting range. Good linearity between capacitance and relative humidity (RH) has been achieved for the RH range from 6% to 94%. According to a wireless monitoring system, even at 250 kHz, the sensor can still monitor the nuance of the humidity difference between 40% and 43% and exhibited an ultrafast response time (0.3 s) and recovery time (0.7 s). Furthermore, the consistent and stable sensing performance after long-time measurements for 100 days and bending tests for 500 cycles also demonstrated a long-time humidity detecting stability and mechanical flexibility for the Gly-K 2 CO 3 flour-based humidity sensor. Humidity sensing mechanisms were thoroughly investigated through SEM-EDX, FTIR, XPS, and complex impedance spectroscopies. The enhanced sensing performance, wide humidity detecting range, and long-time stability are attributed to the ionic conductivity from K 2 CO 3 and the hydrogen-bond interaction between H 2 O and enormous hydrophilic groups, such as hydroxyl and amino groups in the flour-based networks and binary solvent.

Transparent tubes with functions of heating and temperature measurement are badly required in the visualization investigation of two-phase flows and flow-boiling heat transfer. In order to prepare such a tube, we introduced a cost-effective and energy-efficient procedure of hypergravity-assisted chemical liquid deposition (HACLD) to produce transparent and conductive silver (Ag) films on the inner surfaces of quartz tubes, typically 50 mm in length and 8 mm in inner diameter with a set-up that was designed and built for this purpose. Precursors of organometallic Ag precursor solutions were prepared by dissolving silver citrate and 1,2-diaminopropane in 2-methoxyethanol with required concentration for the chemical liquid deposition process. Semitransparent and conductive Ag films formed inside the required quartz tubes under specific heating process in hypergravity. One of the films was about 47 nm in thickness, 23 Ω per square sheet resistance, and 30% optical transmittance. This attempt may pave a way for the understanding of the film forming mechanism in hypergravity, and the development of a film preparation technology of HACLD.

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