Biomolecular monitoring in the gastrointestinal tract could offer rapid, precise disease detection and management but is impeded by access to the remote and complex environment. Here, we present an ingestible micro-bio-electronic device (IMBED) for in situ biomolecular detection based on environmentally resilient biosensor bacteria and miniaturized luminescence readout electronics that wirelessly communicate with an external device. As a proof of concept, we engineer heme-sensitive probiotic biosensors and demonstrate accurate diagnosis of gastrointestinal bleeding in swine. Additionally, we integrate alternative biosensors to demonstrate modularity and extensibility of the detection platform. IMBEDs enable new opportunities for gastrointestinal biomarker discovery and could transform the management and diagnosis of gastrointestinal disease.

The recent steady improvements in the performance of the nascent hybrid perovskite photovoltaic (PV) devices have led to power conversion efficiencies that rival the best-performing established PV technologies. However, to scale these laboratory demonstrations to PV module-scale production will require development of scalable deposition methods for perovskite thin films. Every record result for perovskite PVs so far was achieved via spin coating, a technique that is popular in research laboratories for thin-film coating over relatively small device areas, but not considered to be a method that could be used to scale up the manufacturing of perovskite PVs. Significantly larger thin-film areas are needed for future commercial PV products. Hence, some researchers have focused their efforts on perovskite deposition techniques that can be considered as scalable for mass production and have achieved notable results even on large areas. Here, we present an overview of the solution-based and vapor-based deposition processes; we explain their influence on the molecular crystal growth behavior of perovskite thin films and discuss the morphology as well as other material quality characteristics. By presenting a comprehensive comparison of the deposition techniques and the corresponding performance parameters for different device sizes, we intent to guide the growing research community through the methods that might enable mass production of perovskite solar products.

The authors would like to thank the two anonymous reviewers for their insightful and constructive comments that improved the quality of our work as well as the Ministry of Economic Affairs and Climate Policy of the Netherlands for its financial support enabling the research behind this publication.

Low viscosity rapid drying perovskite formulations designed to give high quality solar films when slot-die coated on flexible roll-to-roll compatible substrates are developed .

Intensive research of hybrid metal-halide perovskite materials for use as photoactive materials has resulted in an unmatched increase in the power conversion efficiency of perovskite photovoltaics (PVs) over the last couple of years. Now that lab-fabricated perovskite devices rival the efficiency of silicon PVs, the next challenge of scalable mass manufacturing of large perovskite PV panels remains to be solved. For that purpose, it is still unclear which manufacturing method will provide the lowest processing cost and highest quality solar cells. Vapor deposition has been proven to work well for perovskites as a controllable and repeatable thin-film deposition technique but with processing speeds currently too slow to adequately lower the production costs. Addressing this challenge, in the present work, we demonstrate a high-speed vapor transport processing technique in a custom-built reactor that produces high-quality perovskite films with unprecedented deposition speed exceeding 1 nm/s, over 10× faster than previous vapor deposition demonstrations. We show that the semiconducting perovskite films produced with this method have excellent crystallinity and optoelectronic properties with 10 ns charge carrier lifetime, enabling us to fabricate the first photovoltaic devices made by perovskite vapor transport deposition. Our experiments are guided by computational fluid dynamics simulations that also predict that this technique could lead to deposition rates on the order of micrometers per second. This, in turn, could enable cost-effective scalable manufacturing of the perovskite-based solar technologies.

Printed lead‐based perovskite photovoltaics (PV) have gained interest due to their potential to be manufactured with scalable roll‐to‐roll techniques. In industrial scale‐up, toxicity of inks can constrain roll‐to‐roll manufacturing due to the added cost of managing toxic effluents. Due to solvent toxicity, few perovskite solution chemistries in published works are scalable to gigawatt production capacity at low cost. Herein, it is shown that for scalable PV production, the use of aprotic polar solvents should be avoided due to their overall toxicity. Compliance with worldwide worker safety regulations for solvent exposure limits could require additional air handling requirements for some solvents, which in turn would affect cost‐effectiveness. It is shown that costs associated with handling of hazardous substances can be significant and estimate an added cost of ¢3.7/W for dimethylformamide (DMF)‐based inks. To solve this problem, a new perovskite ink solvent system is developed that is composed entirely of ether and alcohol, which has an effective exposure limit 14× higher than DMF, making it suitable for industrial coating processes. It is shown that the new ink solvent system is capable of fabricating high‐efficiency perovskite solar cells processed in 1 min on a standard roll‐to‐roll system.

Gating thermal transport is a key requirement in smart heat exchangers used in a variety of applications such as electronics and energy generation. Here, we demonstrate a high on-off ratio thermal valve using magnetic nanofluids actuated by a non-uniform magnetic field. Using nanofluids comprised of magnetic nanoparticles in paraffin oil, we obtain on-off ratios as high as 16, which is more than 5-fold higher than that seen in comparable nanofluids with uniform magnetic fields. Analysis of these results using heat transfer modeling shows that the remarkable enhancement arises from magneto-thermally activated convection due to field gradients. Such convective thermal gating could be promising for applications.

This manuscript introduces solvent toxicity in solar perovskite ink chemistries as a major technoeconomic limitation for the growth of the technology. More specifically, the capital and operational cost of handling such toxic chemicals to maintain a safe working environment can lead to significant added costs. As all record power conversion efficiency devices to date have been solution processed, this represents a major challenge for the perovskite optoelectronic field and of printed electronics as a whole. Knowing this limitation, we propose that solvent selections for ink chemistries should be more quantitative and focus on lowering toxicity. To this end, we show that a Hansen solubility model is effective in predicting ink systems using lower toxicity solvents. We also show that inks formed from this method are applicable for high-speed slot-die coating, limiting the need for long anneal times. These methods and results demonstrate a useful framework for quantitatively engineering solvent systems with reduced toxicity while simultaneously maintaining and surpassing performance. It therefore provides a pathway and major step forward towards the commercialization of solution coated perovskite technologies.