84 research outputs found
Explainable machine learning to enable high-throughput electrical conductivity optimization of doped conjugated polymers
The combination of high-throughput experimentation techniques and machine
learning (ML) has recently ushered in a new era of accelerated material
discovery, enabling the identification of materials with cutting-edge
properties. However, the measurement of certain physical quantities remains
challenging to automate. Specifically, meticulous process control,
experimentation and laborious measurements are required to achieve optimal
electrical conductivity in doped polymer materials. We propose a ML approach,
which relies on readily measured absorbance spectra, to accelerate the workflow
associated with measuring electrical conductivity. The first ML model
(classification model), accurately classifies samples with a conductivity >~25
to 100 S/cm, achieving a maximum of 100% accuracy rate. For the subset of
highly conductive samples, we employed a second ML model (regression model), to
predict their conductivities, yielding an impressive test R2 value of 0.984. To
validate the approach, we showed that the models, neither trained on the
samples with the two highest conductivities of 498 and 506 S/cm, were able to,
in an extrapolative manner, correctly classify and predict them at satisfactory
levels of errors. The proposed ML workflow results in an improvement in the
efficiency of the conductivity measurements by 89% of the maximum achievable
using our experimental techniques. Furthermore, our approach addressed the
common challenge of the lack of explainability in ML models by exploiting
bespoke mathematical properties of the descriptors and ML model, allowing us to
gain corroborated insights into the spectral influences on conductivity.
Through this study, we offer an accelerated pathway for optimizing the
properties of doped polymer materials while showcasing the valuable insights
that can be derived from purposeful utilization of ML in experimental science.Comment: 33 Pages, 17 figure
Automated Electrokinetic Stretcher for Manipulating Nanomaterials
In this work, we present an automated platform for trapping and stretching
individual micro- and nanoscale objects in solution using electrokinetic
forces. The platform can trap objects at the stagnation point of a planar
elongational electrokinetic field for long time scales, as demonstrated by the
trapping of ~100 nanometer polystyrene beads and DNA molecules for minutes,
with a standard deviation in displacement from the trap center < 1 micrometer.
This capability enables the stretching of deformable nanoscale objects in a
high-throughput fashion, as illustrated by the stretching of more than 400 DNA
molecules within ~4 hours. The flexibility of the electrokinetic stretcher
opens up numerous possibilities for contact-free manipulation, with size-based
sorting of DNA molecules performed as an example. The platform described
provides an automated, high-throughput method to track and manipulate objects
for real-time studies of micro- and nanoscale systems.Comment: 9 pages, 7 figure
Constructing Custom Thermodynamics Using Deep Learning
One of the most exciting applications of AI is automated scientific discovery
based on previously amassed data, coupled with restrictions provided by the
known physical principles, including symmetries and conservation laws. Such
automated hypothesis creation and verification can assist scientists in
studying complex phenomena, where traditional physical intuition may fail. Of
particular importance are complex dynamic systems where their time evolution is
strongly influenced by varying external parameters. In this paper we develop a
platform based on a generalised Onsager principle to learn macroscopic
dynamical descriptions of arbitrary stochastic dissipative systems directly
from observations of their microscopic trajectories. We focus on systems whose
complexity and sheer sizes render complete microscopic description impractical,
and constructing theoretical macroscopic models requires extensive domain
knowledge or trial-and-error. Our machine learning approach addresses this by
simultaneously constructing reduced thermodynamic coordinates and interpreting
the dynamics on these coordinates. We demonstrate our method by studying
theoretically and validating experimentally, the stretching of long polymer
chains in an externally applied field. Specifically, we learn three
interpretable thermodynamic coordinates and build a dynamical landscape of
polymer stretching, including (1) the identification of stable and transition
states and (2) the control of the stretching rate. We further demonstrate the
universality of our approach by applying it to an unrelated problem in a
different domain: constructing macroscopic dynamics for spatial epidemics,
showing that our method addresses wide scientific and technological
applications
Accelerating Materials Development via Automation, Machine Learning, and High-Performance Computing
Successful materials innovations can transform society. However, materials
research often involves long timelines and low success probabilities,
dissuading investors who have expectations of shorter times from bench to
business. A combination of emergent technologies could accelerate the pace of
novel materials development by 10x or more, aligning the timelines of
stakeholders (investors and researchers), markets, and the environment, while
increasing return-on-investment. First, tool automation enables rapid
experimental testing of candidate materials. Second, high-throughput computing
(HPC) concentrates experimental bandwidth on promising compounds by predicting
and inferring bulk, interface, and defect-related properties. Third, machine
learning connects the former two, where experimental outputs automatically
refine theory and help define next experiments. We describe state-of-the-art
attempts to realize this vision and identify resource gaps. We posit that over
the coming decade, this combination of tools will transform the way we perform
materials research. There are considerable first-mover advantages at stake,
especially for grand challenges in energy and related fields, including
computing, healthcare, urbanization, water, food, and the environment.Comment: 22 pages, 3 figure
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