Inspired by the collective intelligence in natural swarms, microrobotic agents have been controlled to form artificial swarms for targeted drug delivery, enhanced imaging, and hyperthermia. Different from these well-investigated tasks, this work aims to develop microrobotic swarms for embolization, which is a clinical technique used to block blood vessels for treating tumors, fistulas, and arteriovenous malformations. Magnetic particle swarms were formed for selective embolization to address the low selectivity of the present embolization technique that is prone to cause complications such as stroke and blindness. We established an analytical model that describes the relationships between fluid viscosity, flow rate, branching angle, magnetic field strength, and swarm integrity, based on which an actuation strategy was developed to maintain the swarm integrity inside a targeted region under fluidic flow conditions. Experiments in microfluidic channels, ex vivo tissues, and in vivo porcine kidneys validated the efficacy of the proposed strategy for selective embolization.
Heart
beating is triggered by the generation and propagation of
action potentials through the myocardium, resulting in the synchronous
contraction of cardiomyocytes. This process highlights the importance
of electrical and mechanical coordination in organ function. Investigating
the pathogenesis of heart diseases and potential therapeutic actions in vitro requires biosensing technologies which allow for
long-term and simultaneous measurement of the contractility and electrophysiology
of cardiomyocytes. However, the adoption of current biosensing approaches
for functional measurement of in vitro cardiac models
is hampered by low sensitivity, difficulties in achieving multifunctional
detection, and costly manufacturing processes. Leveraging carbon-based
nanomaterials, we developed a biosensing platform that is capable
of performing on-chip and simultaneous measurement of contractility
and electrophysiology of human induced pluripotent stem-cell-derived
cardiomyocyte (iPSC-CM) monolayers. This platform integrates with
a flexible thin-film cantilever embedded with a carbon black (CB)-PDMS
strain sensor for high-sensitivity contraction measurement and four
pure carbon nanotube (CNT) electrodes for the detection of extracellular
field potentials with low electrode impedance. Cardiac functional
properties including contractile stress, beating rate, beating rhythm,
and extracellular field potential were evaluated to quantify iPSC-CM
responses to common cardiotropic agents. In addition, an in
vitro model of drug-induced cardiac arrhythmia was established
to further validate the platform for disease modeling and drug testing.
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