Measuring and modelling the thermal behavior of LEDs in structural electronics

Abstract Structural electronics consists of printed electronics and silicon-based rigid electronics and load-bearing supporting parts of a device (plastic, glass etc.). One interesting example of structural electronics is large area elements in which light emitting diodes (LEDs) are embedded into the glass laminate. LEDs are used as light sources to create i.e. smart surfaces for the architectural and automotive industry. Once the LEDs are embedded into the structure, they undergo the high temperature conditions and stresses, which are known to have an impact on their lifetime. Many of these aspects are not known for structural electronics. In this study, a thermal simulation model for surface mounted LED on polymer substrate was designed in Comsol Multiphysics -simulation software and the validity of it was evaluated with T3ster measurements. According to measurements, the simulation model is accurate and temperature variations between the simulation and the measurement results was less than 1.0 %. Developed model could be used as a basis for designing the structural LED elements and evaluating their performance characteristics in different user cases

The effect of torsional bending on reliability and lifetime of printed silver conductors

Abstract Capability of high-speed and low-cost manufacturing makes the printing techniques a very promising approach for large-area flexible electronics mass manufacturing. Due to fast and intensive technology development, the lack of knowledge about the reliability and lifetime of printed electronics is obvious, requiring further investigation. Especially, the effect of torsional bending on lifetime is a mostly unexplored field of reliability testing. In this article, a torsional bending test of parallel printed silver conductors (0.3-, 0.5-mm pitch) on polymer substrate (polyethylene terephthalate, 125-μm thickness) was conducted and analyzed. According to the experimental results, torsional bending causes wear-out type failures in conductors and the length-to-width (LTW) ratio of the sample’s substrate was observed to have a significant impact on reliability. If the LTW ratio is smaller than 3, the lifetime of printed conductor seems to collapse and samples lasted for approximately only 17 bending cycles on average. Lifetime was improved by increasing the LTW ratio and samples withstood over hundreds of cycles with LTW ratio of higher than 15. However, the distance of a conductor from the edge of the substrate was not observed to have any significant influence on the reliability under torsional bending

Hybrid thermal modeling to predict LED thermal behavior in hybrid electronics

Abstract Hybrid structural electronics (HSE) consists of printed electronics, conventional rigid electronics, and load-bearing supporting parts of a device (plastic, glass etc.). Extra-large area and flexible lighting elements with embedded light-emitting diodes (LEDs) are an example of such applications. LEDs can be used, for example, as light sources, to create smart surfaces for the architectural or automotive industry. Once the LEDs are embedded into the structure, they cannot be replaced. To make sustainable HSE products with long lifetime, the new type of designs is needed. The elements of HSE undergo conditions with elevated thermal stresses while in operation. That is known to have an impact on their performance and lifetime, thus making a proper heat management of the LED crucial. Due to the novel additive manufacturing methods, structures, and unconventional material combinations, many thermal management related aspects are not known. In this study, a two-step hybrid method, including thermal modeling and measurements, is used to estimate the thermal behavior of a surface-mounted LED on polymer substrate used in HSE. The model is created and simulated in COMSOL Multiphysics. The validity and accuracy of the model’s thermal behavior are verified through measurements with thermal transient measurements. Based on the experimental verification, the proposed simulation model only has small (less than 2%) temperature variations when compared with measurements. Hence, the developed model can be used as a basis for designing structural LED elements and predicting their performance characteristics in different user cases

Erythroid/megakaryocytic differentiation confers BCL-XL dependency and venetoclax resistance in acute myeloid leukemia

Funding Information: This study was supported by the Cancer Foundation Finland, the Helsinki Institute of Life Science (HiLIFE) Fellow grants, the Academy of Finland (grant 1320185 ), the Sigrid Jusélius Foundation , the Finnish Cancer Institute , the Finnish Medical Foundation , University of Helsinki , and the Finnish special governmental subsidy for health sciences, research, and training . The FIMM High Throughput Biomedicine Unit is financially supported by the University of Helsinki (HiLIFE) and Biocenter Finland. O.D. was supported by the K. Albin Johansson Foundation , the Emil Aaltonen Foundation , and the Juhani Aho foundation . Publisher Copyright: © 2023 The American Society of HematologyMyeloid neoplasms with erythroid or megakaryocytic differentiation include pure erythroid leukemia, myelodysplastic syndrome with erythroid features, and acute megakaryoblastic leukemia (FAB M7) and are characterized by poor prognosis and limited treatment options. Here, we investigate the drug sensitivity landscape of these rare malignancies. We show that acute myeloid leukemia (AML) cells with erythroid or megakaryocytic differentiation depend on the antiapoptotic protein B-cell lymphoma (BCL)-XL, rather than BCL-2, using combined ex vivo drug sensitivity testing, genetic perturbation, and transcriptomic profiling. High-throughput screening of >500 compounds identified the BCL-XL–selective inhibitor A-1331852 and navitoclax as highly effective against erythroid/megakaryoblastic leukemia cell lines. In contrast, these AML subtypes were resistant to the BCL-2 inhibitor venetoclax, which is used clinically in the treatment of AML. Consistently, genome-scale CRISPR-Cas9 and RNAi screening data demonstrated the striking essentiality of BCL-XL-encoding BCL2L1 but not BCL2 or MCL1, for the survival of erythroid/megakaryoblastic leukemia cell lines. Single-cell and bulk transcriptomics of patient samples with erythroid and megakaryoblastic leukemias identified high BCL2L1 expression compared with other subtypes of AML and other hematological malignancies, where BCL2 and MCL1 were more prominent. BCL-XL inhibition effectively killed blasts in samples from patients with AML with erythroid or megakaryocytic differentiation ex vivo and reduced tumor burden in a mouse erythroleukemia xenograft model. Combining the BCL-XL inhibitor with the JAK inhibitor ruxolitinib showed synergistic and durable responses in cell lines. Our results suggest targeting BCL-XL as a potential therapy option in erythroid/megakaryoblastic leukemias and highlight an AML subgroup with potentially reduced sensitivity to venetoclax-based treatments.Peer reviewe

Erythroid/megakaryocytic differentiation confers BCL-XL dependency and venetoclax resistance in acute myeloid leukemia

Myeloid neoplasms with erythroid or megakaryocytic differentiation include pure erythroid leukemia, myelodysplastic syndrome with erythroid features, and acute megakaryoblastic leukemia (FAB M7) and are characterized by poor prognosis and limited treatment options. Here, we investigate the drug sensitivity landscape of these rare malignancies. We show that acute myeloid leukemia (AML) cells with erythroid or megakaryocytic differentiation depend on the antiapoptotic protein B-cell lymphoma (BCL)-XL, rather than BCL-2, using combined ex vivo drug sensitivity testing, genetic perturbation, and transcriptomic profiling. High-throughput screening of >500 com-pounds identified the BCL-XL-selective inhibitor A-1331852 and navitoclax as highly effective against erythroid/megakaryoblastic leukemia cell lines. In contrast, these AML subtypes were resistant to the BCL-2 inhibitor venetoclax, which is used clinically in the treatment of AML. Consistently, genome-scale CRISPR-Cas9 and RNAi screening data demonstrated the striking essentiality of BCL-XL-encoding BCL2L1 but not BCL2 or MCL1, for the survival of erythroid/megakaryoblastic leukemia cell lines. Single-cell and bulk transcriptomics of patient samples with erythroid and megakaryoblastic leukemias iden-tified high BCL2L1 expression compared with other subtypes of AML and other hematological malignancies, where BCL2 and MCL1 were more prominent. BCL-XL inhibition effectively killed blasts in samples from patients with AML with erythroid or megakaryocytic differentiation ex vivo and reduced tumor burden in a mouse erythroleukemia xenograft model. Combining the BCL-XL inhibitor with the JAK inhibitor ruxolitinib showed synergistic and durable responses in cell lines. Our results suggest targeting BCL-XL as a potential therapy option in erythroid/mega-karyoblastic leukemias and highlight an AML subgroup with potentially reduced sensitivity to venetoclax-based treatments.Peer reviewe