Viewing stomata in action: Autonomous in planta imaging of individual stomatal movement links morphology and kinetics

Stomata regulate plant gas exchange with the environment, balancing between water loss and CO2 uptake. Gas exchange dynamics are influenced by traits such as stomatal morphology, size and density, which are commonly investigated using imprints and manual microscopy, methods that are destructive and time consuming. Moreover, these microscopic properties are statically sampled and related to the dynamic ensemble behavior: gas exchange of an entire plant or part of a leaf. Knowledge on how morphology, size and density of stomata influence the movement of individual stomata is limited. We developed a compact microscope system that can measure the kinetics of tens of stomata in vivo simultaneously, with sub-minute time resolution. The system can be deployed in the plant’s growth environment, at minimal impact on leaf microclimate. The characteristics of our microscope and data analyses are described, and we demonstrate its capabilities on Chrysanthemum morifolium with novel insight into individual stomata’s contribution to water-use efficienc

Mesenchymal inflammation drives genotoxic stress in hematopoietic stem cells and predicts disease evolution in human pre-leukemia

Mesenchymal niche cells may drive tissue failure and malignant transformation in the hematopoietic system but the molecular mechanisms and their relevance to human disease remain poorly defined. Here, we show that perturbation of mesenchymal cells in a mouse model of the preleukemic disorder Shwachman-Diamond syndrome induces mitochondrial dysfunction, oxidative stress and activation of DNA damage responses in hematopoietic stem and progenitor cells. Massive parallel RNA sequencing of highly purified mesenchymal cells in the mouse model and a range of human preleukemic syndromes identified p53-S100A8/9-TLR inflammatory signaling as a common driving mechanism of genotoxic stress. Transcriptional activation of this signaling axis in the mesenchymal niche predicted leukemic evolution and progression-free survival in myelodysplastic syndrome, the principal leukemia predisposition syndrome. Collectively, our findings reveal a concept of mesenchymal niche-induced genotoxic stress in heterotypic stem and progenitor cells through inflammatory signaling as an actionable determinant of disease outcome in human preleukemia

Modeling, Fabrication, and Testing of a 3D-Printed Coriolis Mass Flow Sensor

This paper presents the modeling, fabrication, and testing of a 3D-printed Coriolis mass flow sensor. The sensor contains a free-standing tube with a circular cross-section printed using the LCD 3D-printing technique. The tube has a total length of 42 mm, an inner diameter of about 900 µm, and a wall thickness of approximately 230 µm. The outer surface of the tube is metalized using a Cu plating process, resulting in a low electrical resistance of 0.5 Ω. The tube is brought into vibration using an AC current in combination with a magnetic field from a permanent magnet. The displacement of the tube is detected using a laser Doppler vibrometer (LDV) that is part of a Polytec MSA-600 microsystem analyzer. The Coriolis mass flow sensor has been tested over a flow range of 0–150 g/h for water, 0–38 g/h for isopropyl alcohol (IPA), and 0–50 g/h for nitrogen. The maximum flow rates of water and IPA resulted in less than a 30 mbar pressure drop. The pressure drop at the maximum flow rate of nitrogen is 250 mbar

Flow-Independent Thermal Conductivity and Volumetric Heat Capacity Measurement of Pure Gases and Binary Gas Mixtures Using a Single Heated Wire

Among the different techniques for monitoring the flow rate of various fluids, thermal flow sensors stand out for their straightforward measurement technique. However, the main drawback of these types of sensors is their dependency on the thermal properties of the medium, i.e., thermal conductivity (k), and volumetric heat capacity (ρcp). They require calibration whenever the fluid in the system changes. In this paper, we present a single hot wire suspended above a V-groove cavity that is used to measure k and ρcp through DC and AC excitation for both pure gases and binary gas mixtures, respectively. The unique characteristic of the proposed sensor is its independence of the flow velocity, which makes it possible to detect the medium properties while the fluid flows over the sensor chip. The measured error due to fluctuations in flow velocity is less than ±0.5% for all test gases except for He, where it is ±6% due to the limitations of the measurement setup. The working principle and measurement results are discussed

A miniature microclimate thermal flow sensor for horticultural applications

Closely packed plant canopies have a negative influence on the uniformity of conditioned air and therefore induce physiological disorders inside plant production systems. Real-time leaf-level flow measurements help to improve the microclimate. This application needs a small and low-cost flow sensor for a flow regime up to 1 m/s . The chip that is presented in this paper consists of five suspended heavily p-doped silicon beams with resistors integrated in the tip. A fluid flow along these tips causes a temperature difference between the resistors by convective heat transfer, enabling calorimetric flow sensing. The 4.4 mm by 3.6 mm sensor is realized in a three-mask versatile fabrication process. The sensor shows a range of 1 m/s to 3 m/s for air with a maximum sensitivity of 1.8 mVs/m and a standard deviation-based accuracy of 3.6 cm/s. The sensor design is easily scalable in theory, hence, a redesign will be made with a slightly lower flow range to fully meet the requirements for the application

Development of Soft sEMG Sensing Structures Using 3D-Printing Technologies

3D printing of soft EMG sensing structures enables the creation of personalized sensing structures that can be potentially integrated in prosthetic, assistive and other devices. We developed and characterized flexible carbon-black doped TPU-based sEMG sensing structures. The structures are directly 3D-printed without the need for an additional post-processing step using a low-cost, consumer grade multi-material FDM printer. A comparison between the gold standard Ag/AgCl gel electrodes and the 3D-printed EMG electrodes with a comparable contact area shows that there is no significant difference in the EMG signals’ amplitude. The sensors are capable of distinguishing a variable level of muscle activity of the biceps brachii. Furthermore, as a proof of principle, sEMG data of a 3D-printed 8-electrode band are analyzed using a patten recognition algorithm to recognize hand gestures. This work shows that 3D-printed sEMG electrodes have great potential in practical application

Massive Parallel NEMS Flow Restriction Fabricated Using Self-Aligned 3D-Crystallographic Nanolithography

We introduce a massive parallel NEMS flow restriction nano-slit array fabricated in a wafer scale process using self-aligned 3D-nanolithography on sharp convex corners created by anisotropic etching of the silicon crystal. The device consists of an array of 50.000 slits, all having a length of ∼360 nm and a width of ∼6 nm. A relatively low resistance (short pore throat) configuration ensures high throughput on the order of 25μ g/s at 4 bar differential pressure. A dedicated hierarchical mechanical design consisting of on-membrane supports within a larger support structure enables operation pressures over 6 bar