The combination of biliary stent with photodynamic and chemotherapy seemed to be a beneficial palliative treatment of unresectable cholangiocarcinoma. However, by intravenous delivery to the target tumor the distribution of the drug had its limitations and caused serious side effect on non-target organs. Therefore, in this study, we are going to develop a localized eluting stent, named PDT-chemo stent, covered with gemcitabine (GEM) and hematoporphyrin (HP). The prototype of PDT-chemo stent was made through electrospinning and electrospraying dual-processes with an electrical charge to cover the stent with a drug-storing membrane from polymer liquid. The design of prototype used PU as the material of the backing layer, and PCL/PEG blends in different molar ratio of 9:1 and of 1:4 were used in two drug-storing layers with GEM and HP loaded respectively. The optical microscopy revealed that the backing layer was formed in fine fibers from electrospinning, while drug-storing layers, attributed to the droplets from electrospraying process. The covered membrane, the morphology of which was observed by scanning electron microscopy (SEM), covered the stent surface homogeneously without crack appearances. The GEM had almost 100% of electrosprayed efficiency than 70% HP loaded on the covered membrane due to the different solubility of drug in PEG/PCL blends. Drug release study confirmed the two-phased drug release pattern by regulating in different molar ratio of PEG/PCL blends polymer. The result proves that the PDT-chemo stent is composed of a first burst-releasing phase from HP and a later slow-releasing phase from GEM eluting. This two-phase of drug eluting stent may provide a new prospect of localized and controlled release treatment for cholangiocarcinoma disease.

This paper presents a nanosecond-fiber-laser-based method for manufacturing polycrystalline-diamond (PCD) tool blanks. The effects of variations in the process path and operating parameters on the cut-surface morphology and surface-quality of the processed PCD workpieces have been analyzed. The results obtained in this study reveal the reactive fusion cutting mechanism to yield a processing depth of 155.2 µm at 30-W average laser power, 200-ns pulse width, and 30-kHz pulse frequency. The successful cutting of a 1.2-mm-thick PCD workpiece via implementation of the horizontal-shifting and vertical layer–by-layer processing methods is reported. Compared to the wire-electrical-discharge machining (WEDM), the proposed approach yields superior cut-surface roughness (Ra = 0.378 µm). Moreover, the laser processing was performed on a single-axis curved stage, on which the workpiece placed at an inclination during laser cutting and finishing. Thus, a PCD insert with an orthogonally cut edge, flat and pit-free finishing surface, and excellent tool-surface roughness (Ra = 0.202 µm) was obtained, thereby verifying the feasibility of the proposed approach. Furthermore, it is evident that the nanosecond-fiber laser can be used to not only cut and finish PCD inserts but also produce PCD workpieces oriented at different rake and clearance angles.

This paper presents the first try to fabricate degradable polylactic acid (PLA) biomedical stents with round edges by the multi-axis micro-milling process. Conventionally biomedical stents are produced by laser processing. Post-processing operations are usually required to handle sharp edges and thermal defects of the stent due to laser processing. A computer graphics software package was used to design the strut structures with round corners of the PLA stent. A PLA tube was first created using injection molding, and a degradable biomedical stent was then fabricated through micro-milling by using a five-axis computer numerical control (CNC) machine tool. This study investigated the error in the rotation center that can occur during five-axis micro-milling. Data obtained from experiments on center-of-rotation errors were substituted into homogeneous coordinate conversion formulas. Center-of-rotation errors in the five-axis machine tool were compensated for improving the milling precision (A and C axes) to be within 5 $\mathsf{\mu }$ m. Furthermore, milling parameter optimization experiments were conducted, which determined the optimal conditions for milling PLA to be a spindle speed of 60,000 rpm, feed per tooth of 0.005 mm, and feed rate of 600 mm/min, and achieved the minimum burr 0.01 mm and the average surface roughness (Ra) 0.4 $\mathsf{\mu }$ m. These optimal cutting parameters will be used in the following actual stent processing experiments. Finally, the error compensation and optimal parameters were combined in a CAM software package and layered spiral micromilling to machine the actual stent. The experimental results revealed that the combination of five-axis micro-milling led to the successful fabrication of a degradable biomedical stent (stent diameter = 6 mm, strut width = 0.3 mm, and radius at round corners = 0.1 mm). The machined actual stent had cross-section height and width errors within 0.01 mm, and arc depth of cut variation within 6 $\mathsf{\mu }$ m. In addition, the PLA stent machining results indicated a rebound of approximately 33% at the strut round edge machining. This work may also open up future possibilities for complex three-dimensionally structured biomedical stents for better performance and special functionality.

In this study, a non-invasive pressure monitoring system that is portable and convenient was designed for detecting compartment syndrome. The system combines a wireless module and smartphone, which aids in the achievement of mHealth objectives, specifically, the continuous monitoring of the compartment pressure in patients. A compartment syndrome detecting method using a wireless sensor system and finite element analysis is developed and verified with an in vitro lower-leg model by rapid prototyping. The sensor system is designed to measure a five point pressure variation from the outside of the lower leg and transmit the data to a smartphone via Bluetooth. The analysis model based on the finite element method is employed to calculate the change of pressure and volume inside the four compartments of the lower leg. The in vitro experimental results show that the non-invasive detecting method can monitor the compartment pressure and provide a warning for the occurrence of compartment syndrome if the compartment pressure is higher than 30 mmHg. Furthermore, the theoretical simulation of the real lower leg shows similar trends to those of the in vitro experiments and can promptly detect the occurrence of compartment syndrome. Measured pressure values exceeding 6.3, 2.7, and 2.8 kPa for the three sensors contacting the outside centers of the superficial posterior, anterior, and lateral compartments, respectively, can indicate that each compartment contains a pressure higher than 30 mmHg. These results can provide a warning for the risk of compartment syndrome of each compartment. In addition, the measured values from the three sensors contacting the superficial posterior compartment at the outside center, close to the tibia, and close to the lateral compartment exceeding 1.8, 0.7, and 0.7 kPa, respectively, can indicate the risk of deep posterior compartment syndrome.

This study presents the development of a novel biodegradable, self-expanding stent designed to facilitate arteriovenous fistula (AVF) maturation. The stent, made of polylactic acid (PLA), is engineered to be crimped into a standard 6 Fr (2 mm) catheter for delivery and to self-expand, increasing the vein diameter beyond 4.2 mm with the aid of pre-strained elastic lines, thereby enhancing maturation rates. A validated finite element model was utilized to design the stent, ensuring it meets functional requirements with less than 3% strain in both crimped and fully expanded states. The stent prototype was fabricated using a modified fused deposition modeling (FDM) 3D printer, and the Taguchi method was employed to optimize manufacturing parameters, achieving strut width and thickness variations of less than 5%. Experimental validation demonstrated that the PLA stent could be crimped to 2 mm, self-expand to 6.4 mm, and deliver a radial force of 0.08 N/mm, meeting the performance requirements of AVF stents. Additionally, the stent exhibits excellent elasticity post-implantation, minimizing the risk of damage from external forces, and fully degrades after AVF maturation, reducing the risk of long-term vascular obstruction and related complications. This novel stent design offers a promising biodegradable solution for enhancing AVF maturation and improving patient outcomes.