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Laser Sintering of Zn Microparticles and Its Application in Printable Biodegradable Electronics
摘要： The rapid expansion of electronic technology and short lifespan of consumer devices create a huge amount of electronic waste. The disposal of discarded devices represents a serious environmental challenge. Biodegradable devices are able to decompose into benign components after a period of stable operation during its service life, which represents a potential solution to reduce the environmental footprint of electronic technology. The widespread applications of biodegradable electronics are still hampered by the lack of facile manufacturing approach for high quality devices. Here, a laser sintering technique to weld naturally oxidized Zn microparticles into biodegradable conductors is reported. The sintering process is carried out under ambient conditions and compatible with various biodegradable substrates. A low-cost fabrication procedure involving stencil printing and laser treatment is established to create conductive features with excellent conductivity and mechanical durability. The practical suitability of printed Zn conductor is demonstrated by fabricating near-field communication tags, which are flexible and fully functional with the transient behavior modulated by the choice of packaging materials. The printed biodegradable conductor may find potential applications in eco-friendly sensors, transient printed circuit boards, and implantable medical devices.
关键词： biodegradable electronics,transient electronics,printable electronics,laser sintering,biodegradable conductors
更新于2025-09-11 14:15:04
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Characterization and laser-induced degradation of a medical grade polylactide
摘要： In this study, we carried out the structural and thermal characterization of a medical-grade poly (lactide) (PLA) by SEC, TGA, DSC, NMR, ICP-MS and Py-GC/MS. Moreover, we investigated the laser-induced degradation occurring when ultrashort laser pulses (ULP) were employed to cut extremely thin polymer films prepared by solvent-casting. ULP polymer cutting technology is an interesting manufacturing process for its advantages in potential medical applications. In fact, heat transmission to the region surrounding the cuts is limited, so that the incisions are precise and the effects on the regions around them are small. In this way, the need for post-processing is reduced and ULP cutting becomes interesting for industrial applications. However, degradation induced by ULP may occur and compromise the properties of the polymer samples. To investigate this possibility, portions of PLA films, ultrashort laser cut (ULC) and uncut, were analysed by SEC, DSC, NMR and FTIR. Furthermore, PLA oligomers were studied by ESI-MS. Both SEC and NMR showed a decrease in the molecular weight. FTIR, ESI-MS and NMR spectra revealed the presence of olefin end groups originated from a b-H transfer mechanism, induced by heat and/or light (Norrish II mechanism). Additionally, the inspection of the ESI mass spectra highlighted the cleavage of ester bonds related to the Norrish I type mechanism, undetected by the other techniques.
关键词： Polymer degradation,Ultrafast laser sources,Norrish mechanisms,Biodegradable polymers,Polylactide,Micro-cutting
更新于2025-09-11 14:15:04
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Biodegradable Bi <sub/>2</sub> O <sub/>2</sub> Se Quantum Dots for Photoacoustic Imaging-Guided Cancer Photothermal Therapy
摘要： As new 2D layered nanomaterials, Bi2O2Se nanoplates have unique semiconducting properties that can benefit biomedical applications. Herein, a facile top-down approach for the synthesis of Bi2O2Se quantum dots (QDs) in a solution is described. The Bi2O2Se QDs with a size of 3.8 nm and thickness of 1.9 nm exhibit a high photothermal conversion coefficient of 35.7% and good photothermal stability. In vitro and in vivo assessments demonstrate that the Bi2O2Se QDs possess excellent photoacoustic (PA) performance and photothermal therapy (PTT) efficiency. After systemic administration, the Bi2O2Se QDs accumulate passively in tumors enabling efficient PA imaging of the entire tumors to facilitate imaging-guided PTT without obvious toxicity. Furthermore, the Bi2O2Se QDs which exhibit degradability in aqueous media not only have sufficient stability during in vivo circulation to perform the designed therapeutic functions, but also can be discharged harmlessly from the body afterward. The results reveal the great potential of Bi2O2Se QDs as a biodegradable multifunctional agent in medical applications.
关键词： biodegradable,Bi2O2Se,2D layered materials,photothermal agents,photoacoustic imaging
更新于2025-09-11 14:15:04
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Study of Physical and Degradation Properties of 3D-Printed Biodegradable, Photocurable Copolymers, PGSA-co-PEGDA and PGSA-co-PCLDA
摘要： As acrylated polymers become more widely used in additive manufacturing, their potential applications toward biomedicine also raise the demand for biodegradable, photocurable polymeric materials. Polycaprolactone diacrylate (PCLDA) and poly(ethylene glycol) diacrylate (PEGDA) are two popular choices of materials for stereolithography (SLA) and digital light processing additive manufacturing (DLP-AM), and have been applied to many biomedical related research. However, both materials are known to degrade at a relatively low rate in vivo, limiting their applications in biomedical engineering. In this work, biodegradable, photocurable copolymers are introduced by copolymerizing PCLDA and/or PEGDA with poly(glycerol sebacate) acrylate (PGSA) to form a network polymer. Two main factors are discussed: the effect of degree of acrylation in PGSA and the weight ratio between the prepolymers toward the mechanical and degradation properties. It is found that by blending prepolymers with various degree of acrylation and at various weight ratios, the viscosity of the prepolymers remains stable, and are even more 3D printable than pure substances. The formation of various copolymers yielded a database with selectable Young’s moduli between 0.67–10.54 MPa, and the overall degradation rate was significantly higher than pure substance. In addition, it is shown that copolymers fabricated by DLP-AM fabrication presents higher mechanical strength than those fabricated via direct UV exposure. With the tunable mechanical and degradation properties, the photocurable, biodegradable copolymers are expected to enable a wider application of additive manufacturing toward tissue engineering.
关键词： additive manufacturing,poly(glycerol sebacate) acrylate,photocurable polymer,poly(ethylene glycol) diacrylate,digital light processing,polycaprolactone diacrylate,biodegradable polymer
更新于2025-09-09 09:28:46
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Development of a Rapid Prototyping System for Microneedles Using Moving-mask Lithography with Backside Exposure
摘要： Moving-mask lithography with backside exposure was utilized to generate master male mold for biodegradable polymer microneedle production. The microneedle shape was calculated from the exposure dose, mask geometry, and moving trajectory using a newly developed computer simulation. Two conditions (90 μm aperture with 80 μm diameter of circular movement, and 90 μm aperture with 90 μm diameter of circular movement) were selected to evaluate the moving-mask exposure effectiveness. By changing the moving trajectory, two different sizes of microneedles were obtained from a single-size aperture mask. The fabricated microneedle and calculated microneedle geometry showed good qualitative agreement. The geometrical difference was 2% in basal diameter and 8%–16% in height. Using the master male mold, biodegradable polymer microneedles made of chondroitin sulfate C sodium salt (CSC) were fabricated by casting from a poly-dimethylsiloxane female mold. The shape of the biodegradable CSC microneedles showed good agreement with the master male mold.
关键词： backside exposure,biodegradable microneedles,moving-mask lithography
更新于2025-09-09 09:28:46