Medical Design Briefs - August 2024 - 22

Sensors/Targeted Drug Delivery
ity. Depending on which surface of the MEMS contains the
functional elements, the wafer tapes could pull way and damage
key components. The DI water spray often has enough
force to damage MEMS as well, depending on water pressure
and blade wheel speed. A great alternative is laser dicing,
which still uses wafer tapes but does not use DI water, minimizing
the risk of damage to a wafer during singulation. However,
this process singulation method usually requires narrower
saw streets and thinner wafers.
Developing and validating manufacturing processes for
MEMS sensors requires careful planning, expertise, and proper
equipment sets. A dedicated process development stage is
necessary to fine-tune manufacturing steps, take precise measurements,
and perform destructive testing to validate the process.
These ensure that the sensors meet performance and reliability
standards. Using mechanical parts and coupons as
substitutes for expensive, functioning parts during validation
can help reduce costs and streamline the development process.
MEMS sensor packaging is a complex and multifaceted process
that demands careful consideration of various factors. By
addressing these challenges through innovative techniques
and meticulous process development, the potential of MEMS
sensors can be fully realized. Ensuring robust protection and
optimal performance of these sensors paves the way for their
continued integration into diverse applications, driving technological
advancement and enhancing the capabilities of
modern devices.
This article was written by Alfonso Villafuerte, a process engineering
at Promex, Santa Clara, CA. For more information,
visit www.promex.com.
Ultrasound Beam Triggers 'Nanodroplets' to Deliver
Drugs
Novel drug-delivery method is proven safe and efficient for the first time.
University of Utah, Salt Lake City, UT
C
onventional drug delivery is often like cracking a nut
with a sledgehammer. Whether the drug is swallowed,
injected, inhaled, or absorbed through the skin, it ultimately
diffuses to most parts of the body, including those where
it isn't needed - or where it even might cause harm.
But what if the delivery could be targeted at exactly the right
spot? This would allow the total dose to be dramatically lower,
thus minimizing side effects.
Now, U.S. scientists have found a way to perfect a promising,
emerging method that does just that. With their new
protocol, the method is made both safe and efficient for
the first time, hopefully paving the way for first-in-human
trials. The results are published in Frontiers in Molecular
Biosciences.
AB
p = 0.0013
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300 kHZ 900 kHz
Frequency
" Here we show a method to deliver drugs to specific areas of
the body where they are needed. We do so [by] using ultrasound
waves, which trigger drug release from circulating nanocarriers
when focused on the target, " says Matthew G. Wilson, a
graduate research assistant at the University of Utah, and the
study's first author.
" We developed a method to produce stable nanocarriers repeatably,
and identified ultrasound parameters that can activate
them. "
Nanoengineered Droplets
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The nanocarriers are minuscule droplets, between 470 and
550 nm across, with a hollow outer shell composed of polymer
molecules. These polymers have two distinct ends: a hydrophilic
one, which mixes well with watery
solutions like blood and which faces outward,
and a hydrophobic one that
doesn't mix with water and which faces
inward.
PFP (29°) DPF (55°)
Core (boiling point)
PFOB (142°)
Release from nanodroplets with distinct cores under two ultrasound frequency modes. Mean ± s.e.m. propofol
release relative to the amount encapsulated for the two ultrasound frequencies, combined across all cores (A) and
the three cores tested (B). The ultrasound was delivered in 100 ms pulses repeated 60 times over the period of 1
min. The p-value denotes the significance of a two-sample two-sided t-test. (Credit: Frontiers in Molecular Biosciences,
https://doi.org/10.3389/fmolb.2024.1408767)
22
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Within the shell is an inner core of hydrophobic
perfluorocarbons, molecules
that consist mostly of fluorine and carbon,
and which are mixed with an equally
hydrophobic drug of interest. The shells
keep the cores apart, preventing them
from coalescing into a single droplet, and
form a barrier against the immune system.
The effect is much like mayonnaise,
where proteins from eggs form droplets
of encapsulated oils, where otherwise the
oil and water would separate completely.
To release the drug, the researchers
played back an ultrasound - a sound
wave with a frequency beyond the upper
Medical Design Briefs, August 2024
Release %
Release %

http://www.promex.com https://doi.org/10.3389/fmolb.2024.1408767 https://www.medicaldesignbriefs.com

Medical Design Briefs - August 2024

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