Page 613 - IJB-10-3

International Journal of Bioprinting Wireless module system applied on 3D-printed implant

1. Introduction and peripheral measurement systems for data collection.
As a result, current strain sensing devices do not facilitate
Mandibular continuity defects refer to obvious bone or tissue real-time measurements performed by patients themselves
loss in the mandibular region, primarily caused by malignant or within a home setting. Therefore, the prime objective of
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tumors, external traumas, or congenital genetic disorders. this study is to integrate the strain gauge signal processor
These defects can have a detrimental impact on a patient’s into a microchip that can be installed into mandibular
facial aesthetics and may lead to speech and chewing implants to monitor the implant’s biomechanical status at
difficulties, affecting their quality of life. Currently, fibula the initial period after surgery.
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free flap (FFF) surgery used with traditional bone plates to
secure the bone graft is the gold standard for such treatments. In this study, we developed a miniaturized WMS for
Several advantages of this approach include the exit of the strain gauge measurement to achieve early biomechanical
fibular flap from the long vascular pedicle, segmented blood behavior detection in an experimental 3D-printed metal
supply, availability as a composite tissue, and enough bone model of a patient-specific segmental implant (MMPSI)
volume for host dental implants. However, reconstruction after surgery. This system was installed into a 3D-printed
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procedures remain challenging for surgeons because bone mandibular implant for in vitro fatigue mechanical testing
plate fatigue fractures may occur due to pre-bent implants to under different occlusal conditions applied on the simulated
conform to the mandibular curvature. 8-10 Furthermore, these plastic mandibular model after validating the feasibility
implants may not precisely match the patient’s mandibular through cantilever beam modeling and mechanical
curvature, resulting in the inability to fully restore patient tests. The goal was to prevent premature failure through
appearance and bite functionality. understanding the relationship between the received strain
signals from the in vitro simulated mandibular patient-
Recently, metal three-dimensional (3D) printing, specific 3D-printed implant and various occlusal forces.
medical image processing, and computer-aided design
(CAD) technologies were integrated to develop a patient- 2. Materials and methods
specific reconstruction implant for mandibular continuity
defect. This approach was accepted to restore the patient 2.1. WMS design
appearance and mandible structural strength. However, The CYBLE-214015-01 (Infineon Technologies, Neubiberg,
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metal 3D-printed implants introduce certain challenges, Germany) programmable microchip with a built-in low-
particularly in terms of implant weight and the potential power Bluetooth module was employed in this study. The
stress-shielding effect. To address these issues, topology internal amplifier and 12-bit analog-to-digital microchip
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optimization was proposed to preserve the implant converter were utilized for strain gauge signals acquisition
mechanical strength while reducing its excessive weight. at a sampling rate of 1500 Hz. The signals, following
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Nonetheless, the instability of large 3D-printed implant is median filtering, were transmitted to a mobile application
usually associated with their unfavorable biomechanical (APP) via low-power Bluetooth connection at a rate of 20
aspects, including experiencing high stress/strain and data points per second. To achieve power efficiency, the
significant displacement. Abnormal biomechanical microchip system automatically entered a sleep state in case
responses to the 3D-printed implant can result in implant of transmission interruption. The chip awakened to resume
loosening/extensive damage, and the implant might also data capture and transmission upon re-establishing the
become dislodged, penetrating through the adjacent Bluetooth connection. The program design is illustrated in
soft tissue. 14,15 Therefore, ensuring the early detection of Figure 1a. The microchip underwent fabrication processes
biomechanical anomalies in large implants is a critical such as exposure, development, and etching, as depicted in
consideration for mandibular reconstruction treatment. Figure 1b. This chip measured 17.5 mm in length and 12 mm
in width. The primary mobile APP functions can record data
Strain gauge used to measure deformation resulting with data saved in text format and allow the APP interface
from bending forces is a well-established technique in to adjust the adaptation of both the Bluetooth connection
both the mechanical and medical fields. Strain gauges time and the sleep interval time with the microchip to
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work by utilizing piezoelectric materials to deform and reduce chip power consumption. In subsequent steps, the
then amplify the voltage, pass it through a Wheatstone strain gauge and power wires were sequentially soldered to
bridge, and convert it into the strain measurement for the the wireless module chip, forming a WMS to communicate
tested object. In recent years, placing strain gauges within with the mobile APP (Figure 1c).
a bone plate has been proposed to detect and track post-
operative bone healing conditions. 17,18 However, the strain 2.2. WMS validation
signals measurements typically require specific settings Cantilever beam model structural mechanics were used to
and the use of external wearable devices (such as wires) validate the WMS feasibility. Finite element (FE) analysis

Volume 10 Issue 3 (2024) 605 doi: 10.36922/ijb.2553