Strain-Isolating Materials and Interfacial Physics for Soft Wearable Bioelectronics and Wireless,Motion Artifact-Controlled Health Monitoring

Recent developments of micro-sensors and flexible electronics allow for the manufacturing of health monitoring devices, including electrocardiogram (ECG) detection systems for inpatient monitoring and ambulatory health diagnosis, by mounting the device on the chest. Although some commercial devices in reported articles show examples of a portable recording of ECG, they lose valuable data due to significant motion artifacts. Here, a new class of strain-isolating materials, hybrid interfacial physics, and soft material packaging for a strain-isolated, wearable soft bioelectronic system (SIS) is reported. The fundamental mechanism of sensor-embedded strain isolation is defined through a combination of analytical and computational studies and validated by dynamic experiments. Comprehensive research of hard-soft material integration and isolation mechanics provides critical design features to minimize motion artifacts that can occur during both mild and excessive daily activities. A wireless, fully integrated SIS that incorporates a breathable, perforated membrane can measure real-time, continuous physiological data, including high-quality ECG, heart rate, respiratory rate, and activities. In vivo demonstration with multiple subjects and simultaneous comparison with commercial devices captures the SIS's outstanding performance, offering real-world, continuous monitoring of the critical physiological signals with no data loss over eight consecutive hours in daily life, even with exaggerated body movements.     

Using reduced-processing training to improve decision efficiency among perfectionists

Cognition, Technology & Work - Previous research has demonstrated performance inefficiencies among perfectionists, which may be mitigated via the adoption of ‘good enough’...     

Using experimental trapping seasons to explore fisher harvest management uncertainties: is timing everything?

An experimental trapping season was used to address structural and partial controllability uncertainties related to the timing and duration of a fisher (Martes pennanti) trapping season in northern New York. Uncertainties regarding capture vulnerability and harvest effort have thwarted serious consideration of altering the season structure. An experimental extension to the trapping season was implemented in a portion of northern New York to explore these uncertainties. The study found that capture vulnerability did not change between the traditional portion of the season (25 October–10 December) and the experimental season extension (11 December–10 January). Trapping effort was significantly less during the extended portion of the season, in terms of both number of active trappers and mean individual effort. Thus, changes in the cumulative harvest appear to be driven by changes in harvest effort, rather than changes in capture vulnerability. Increasing harvest opportunity in this system does not appear to increase cumulative harvest proportionally.     

The influence of depth and velocity on age‐0 Scaphirhynchus sturgeon prey consumption: Implications for aquatic habitat restoration

After the pallid sturgeon (Scaphirhynchus albus) was listed as endangered in 1990, a variety of management actions focusing on early life history needs have been implemented to aid species recovery. Given the scarcity of age‐0 pallid sturgeon, managers and scientists have relied on sympatric congeners to evaluate the effectiveness of management actions in the short term; however, increased understanding of habitat requirements for age‐0 Scaphirhynchus sturgeon is still needed to appropriately focus management efforts. Recently, a lack of food‐producing and foraging habitats were proposed as potential limiting factors for pallid sturgeon, and the purpose of this study was to evaluate the current definition of these habitats at multiple spatial scales using data from age‐0 Scaphirhynchus sturgeon (shovelnose sturgeon [Scaphirhynchus platyrhynchus] or hybrid [shovelnose sturgeon x pallid sturgeon]). Results showed the water depths and velocities that currently define age‐0 pallid sturgeon foraging habitat had little effect on age‐0 Scaphirhynchus sturgeon prey consumption. Similar results occurred when evaluating the relationship between prey consumption and food‐producing habitat present 10, 20, and 30 days before capture. Assuming that individuals captured during this study were a valid surrogate, these results suggest that increasing foraging and food‐producing habitat as defined by the current depth and velocity criteria is unlikely to result in the desired benefits of increased growth and survival of age‐0 pallid sturgeon.     

A robust k ∼ 2.3 SiCOH low-k film formed by porogen removal with UV-cure

Aurora^®ELK films were fabricated by PE-CVD of a SiCOH matrix precursor and an organic porogen material. The porogen material is removed during a subsequent thermally assisted UV-cure step with a short wavelength UV-lamp (λ < 200 nm). This results in film thickness shrinkage of 13.2% and a robust low-k film with k-value ∼ 2.3, elastic modulus ∼5.0 GPa and intrinsic film stress ∼59 MPa. The microscopic film properties during UV-cure were evaluated by FT-IR. A decrease in the CH_x peak area is related to the porogen removal from the film resulting in a reduced dielectric constant. The decrease of the Si-CH₃ peak and increase in the SiO network area are associated to the network restructuring and increase in elastic modulus. The nature of the Si-H peaks which appear during UV-cure has to be investigated carefully to determine their impact on film reliability. The dielectric diffusion barrier can work as an UV absorption layer which reduces UV-curing of underlying layers and possible UV reflections on interfaces. The SiCN/A-SiCO diffusion barrier film properties during UV-cure show a decrease in k-value, increase in intrinsic film stress and a slight increase in leakage. More research is needed to evaluate the impact of porogen removal by UV-cure on BEOL integration.     

Improving the Back-Propagation Algorithm Using Evolutionary Strategy

In order to overcome the existence of the local minimum in the multilayer perceptron (MLP) implemented with back-propagation (BP) algorithm, the evolutionary strategy (ES) is proposed. Introducing the factors of the chromosome and gene mutation rates, one can enhance the flexibility of the mutation. The bounds of the chromosome and gene mutation rates are derived. Simulation results are shown to verify the theoretical calculations and also suggest appropriate strategy parameter values. The theoretical results are studied using the MLP-based decision feedback equalizer (MLP DFE) scenarios. The results indicate that the evolutionary strategy outperforms the BP algorithm     

Domain wall motion in synthetic Co2Si nanowires

We report the synthesis of single crystalline Co(2)Si nanowires and the electrical transport studies of single Co(2)Si nanowire devices at low temperature. The butterfly shaped magnetoresistance shows interesting ferromagnetic features, including negative magnetoresistance, hysteretic switch fields, and stepwise drops in magnetoresistance. The nonsmooth stepwise magnetoresistance response is attributed to magnetic domain wall pinning and depinning motion in the Co(2)Si nanowires probably at crystal or morphology defects. The temperature dependence of the domain wall depinning field is observed and described by a model based on thermally assisted domain wall depinning over a single energy barrier.     

A Self‐Powered and Flexible Organometallic Halide Perovskite Photodetector with Very High Detectivity

Flexible and self‐powered photodetectors (PDs) are highly desirable for applications in image sensing, smart building, and optical communications. In this paper, a self‐powered and flexible PD based on the methylammonium lead iodide (CH₃NH₃PBI₃) perovskite is demonstrated. Such a self‐powered PD can operate even with irregular motion such as human finger tapping, which enables it to work without a bulky external power source. In addition, with high‐quality CH₃NH₃PBI₃ perovskite thin film fabricated with solvent engineering, the PD exhibits an impressive detectivity of 1.22 × 10¹³ Jones. In the self‐powered voltage detection mode, it achieves a large responsivity of up to 79.4 V mW^?1 cm^?2 and a voltage response of up to ≈90%. Moreover, as the PD is made of flexible and transparent polymer films, it can operate under bending and functions at 360 ° of illumination. As a result, the self‐powered, flexible, 360 ° omnidirectional perovskite PD, featuring high detectivity and responsivity along with real‐world sensing capability, suggests a new direction for next‐generation optical communications, sensing, and imaging applications.     

An improved explicit scheme for whole-building hygrothermal simulation

Implicit schemes require important sub-iterations when dealing with highly nonlinear problems such as the combined heat and moisture transfer through porous building elements. The computational cost rises significantly when the whole-building is simulated, especially when there is important coupling among the building elements themselves with neighbouring zones and with HVAC (heating ventilation and air conditioning) systems. On the other hand, the classical Euler explicit scheme is generally not used because its stability condition imposes very fine time discretisation. Hence, this paper explores the use of an improved explicit approach—the DuFort–Frankel scheme—to overcome the disadvantage of the classical explicit one and to bring benefits that cannot be obtained by implicit methods. The DuFort–Frankel approach is first compared to the classical Euler implicit and explicit schemes to compute the solution of nonlinear heat and moisture transfer through porous materials. Then, the analysis of the DuFort–Frankel unconditionally stable explicit scheme is extended to the coupled heat and moisture balances on the scale of a one- and a two-zone building models. The DuFort–Frankel scheme has the benefits of being unconditionally stable, second-order accurate in time O(Δt2) and to compute explicitly the solution at each time step, avoiding costly sub-iterations. This approach may reduce the computational cost by twenty as well as it may enable perfect synchronism for whole-building simulation and co-simulation.