Medical Design Briefs - April 2024 - 22

Design Briefs
excerpt from the Journal of the American
Medical Association (JAMA) article:
" Surveillance of all medical devices,
including those modified through PMA
supplements, would become feasible,
enabling safety concerns to be prospectively
identified. More timely notification
could also be provided to patients
who had been treated with a recalled
device, thereby mitigating
harm....
American healthcare is built to facilitate
transactions, and the system's current
transaction standards don't enable
tracking of UDIs. This means that the
over 3.5 million devices with UDIs today
are functionally invisible to the patients
that use them, the providers that purchase
them, and the payers that reimburse
for them. " 2
So, absent an imminent implementation
deadline or other regulatory catalyst,
expect continued UDI expansion
in fits and starts. Many UDI professionals
are not satisfied with the current situation,
but they don't think it is permanent
either.
" I feel we're closer to getting there,
but we're not getting there, " says Wilson.
" I think we're going to overcome
the inertia, " says Capatch of Geisinger.
" There is so much opportunity; that is
what continues to drive us. "
References
1. " A Playbook for Health System Unique Device Identifier
Implementation at the Point of Care, " Nestcc,
2023, https://nestcc.org/nestcc-udi-playbook.
2. Hope Caughron, et al., " Medical Device Modifications
Through Premarket Approval Supplements-Ensuring
Patient Safety, " JAMA, April
12, 2023, https://jamanetwork.com/journals/
jamanetworkopen/fullarticle/2803742
This article was written by Mary Lou
Bosco, Chief Executive Officer, AIM
North America, Warrendale, PA. Contact:
marylou@aimglobal.org. For more
information, visit www.aimglobal.org.
Part 2: Designing Piezo Handpieces for Ultrasonic
Surgery
To prevent overheating during operation of the handpiece, low-loss
piezoelectric materials with a high mechanical grade are used.
By Dr.-Ing. Timo Scholehwar, PI Ceramic
ltrasonic handpieces are being used
with growing frequency in medical
applications, for example, with
minimally invasive surgical procedures
and in dentistry. These instruments, which
include ultrasonic scalpels, phaco handpieces,
and scalers, use acoustic waves to
U
facilitate the processing of hard or soft
tissue. Part 1 of this article , which ran in
March 2023, looked at the general structure,
design variants, and system design of
ultrasonic medical handpieces. Part 2 now
reviews driver design, special applications,
drive electronics, and failure mechanisms.
Driver Design
In principle, a high-power ultrasonic
driver consists of an even number
of hard PZT (lead zirconate titanate)
rings clamped with a bolt between a
base body and an inertial mass (see Figure
1). The resonant frequency and the
deflection of the driver are determined
by the entire structure and not solely
by the properties of the assembled PZT
components. The choice of PZT material
is mainly determined by the available
electronics and cooling. Materials with
high coupling, low internal losses and
medium bandwidth, e.g. PIC 181, PIC
184, or PIC 144, are usually available
(see Table 1).
Ultrasonic handpieces, which include ultrasonic scalpels, phaco handpieces and scalers, use acoustic waves to
facilitate the processing of hard or soft tissue. (Credit: Physik Instrumente)
22
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The electrical contact is established by
means of intermediate electrodes made
of metal foils. Perforated copper-alloy
foils are used to carry the high currents
in resonance operation and to dissipate
the heat from internal losses. The perforation
ensures improved force distribution
over the surface while maintaining
dimensional stability.
Care must be taken to ensure that the
correct surfaces to be clamped are as
parallel as possible. Angular or tapered
surfaces usually lead to immediate failure
during assembly. Undercutting the
inner edges against which the PZT comMedical
Design Briefs, April 2024

https://nestcc.org/nestcc-udi-playbook https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2803742 https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2803742 http://www.aimglobal.org http://www.medicaldesignbriefs.com

Medical Design Briefs - April 2024

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