High-resolution colour and range image capture on a single chip
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On-chip solar power source for self-powered smart microsensors in bulk CMOS process
Enhancing the photoelectric conversion efficiency of on-chip solar cells is crucial for advancing solar energy harvesting in self-powered smart microsensors for Internet of Things applications. Here we show that adopting a center electrode (CE) layout instead of a ring electrode (RE) effectively reduces the shadowing effect of surface electrodes. Using a standard 0.18 μm CMOS process, we fabricated a 0.01 mm² segmented triple-well on-chip solar cell with CEs and highly doped interconnections. Measurements demonstrate a photoelectric conversion efficiency of 25.79% under solar simulator illumination, a 17.49% improvement over conventional designs. This on-chip solar cell is used for on-chip energy harvesting, achieving a maximum end-to-end conversion efficiency of 10.20%, referring to the overall efficiency from incident light power to load power output. The proposed energy harvesting system reliably provides a stable 1 V output to the load, even under varying illumination and load conditions.
Balancing aesthetics and efficiency of coloured opaque photovoltaics
The integration of solar photovoltaics (PV) into buildings and infrastructure necessitates PV elements that are suitable as construction materials and aesthetically pleasing. In this Perspective, we explore how coloured opaque PV technologies blend power generation with visual appeal, providing foundational methods for better balancing aesthetics and efficiency. Our analysis covers the key features and theoretical efficiency limits of coloured opaque PV modules, noting that efficiencies of around 22% are practically achievable across most colours. We provide an overview of various optical materials for PV colourization, focusing on easily mass-producible inorganic pigments, multilayer dielectric thin films and interference pigments that facilitate higher efficiency, and other emerging materials. To boost future development and benchmarking, we propose a design framework that incorporates optical and electrical simulation, along with an inverse optimization algorithm for achieving an optimal coloured PV with targeted colour and maximum efficiency. We also suggest that future studies should include detailed reporting of metrics that involve power conversion performance, colour lightness and chromaticity, and the influence of colouring materials, to facilitate fair performance assessment. Finally, we identify the challenges that remain in enhancing the performance and practical application of coloured opaque PV and offer potential solutions.
A gut-on-a-chip incorporating human faecal samples and peristalsis predicts responses to immune checkpoint inhibitors for melanoma
Patient responses to immune checkpoint inhibitors can be influenced by the gastrointestinal microbiome. Mouse models can be used to study microbiome–host crosstalk, yet their utility is constrained by substantial anatomical, functional, immunological and microbial differences between mice and humans. Here we show that a gut-on-a-chip system mimicking the architecture and functionality of the human intestine by including faecal microbiome and peristaltic-like movements recapitulates microbiome–host interactions and predicts responses to immune checkpoint inhibitors in patients with melanoma. The system is composed of a vascular channel seeded with human microvascular endothelial cells and an intestinal channel with intestinal organoids derived from human induced pluripotent stem cells, with the two channels separated by a collagen matrix. By incorporating faecal samples from patients with melanoma into the intestinal channel and by performing multiomic analyses, we uncovered epithelium-specific biomarkers and microbial factors that correlate with clinical outcomes in patients with melanoma and that the microbiome of non-responders has a reduced ability to buffer cellular stress and self-renew. The gut-on-a-chip model may help identify prognostic biomarkers and therapeutic targets.
Acoustic impedance-based surface acoustic wave chip for gas leak detection and respiratory monitoring
Acoustic impedance enables many interesting acoustic applications. However, acoustic impedance for gas sensing is rare and difficult. Here we introduce a micro-nano surface acoustic wave (SAW) chip based on the acoustic impedance effect to achieve ultra-fast and wide-range gas sensing. We theoretically established the relationship between surface load acoustic impedance and SAW attenuation, and analyzed the influence of acoustic impedance on acoustic propagation loss under different gas/humidity media. Experimental measurements reveal that the differences in acoustic impedance generated by different gases trigger different acoustic attenuation, and can achieve wide-range (0–100 v/v%) gas monitoring, with ultra-fast response and recovery speeds reaching sub-second levels (t90 < 1 s, t10 < 0.5 s) and detection limit of ~1 v/v%. This capability can also be perfectly utilized for human respiratory monitoring, accurately reflecting respiratory status, frequency, and intensity. Consequently, the SAW chip based on the acoustic impedance effect provides a new solution for in-situ detection of gas leaks and precise monitoring of human respiration.
PlomBOX: a low cost bioassay for the sensitive detection of lead in drinking water
This paper reports the design of a biosensor for sensitive, low-cost measurement of lead in drinking water. The biosensor uses a genetically-modified strain of Escherichia coli, which serves as both signal amplifier and reporter of lead in water, measured via colour change. We developed the PlomBOX measurement platform to image this colour change and we demonstrate its capability to detect concentrations as low as the World Health Organisation upper limit for drinking water of 10 ppb. Our approach does not require expensive infrastructure or expert operators, and its automated sensing, detection and result visualisation platform is user-friendly and robust compared to existing lead biosensors—critical features to enable measurement by non-experts at the point of use.
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