Miniaturized reconfigurable three dimensional printed frequency selective surface based microwave absorbers

Three-dimensional printer is widely used in industry, biology, and medical fields. We report a finger prosthesis produced by a three-dimensional scanner and printer for a 67-year-old man with a right thumb amputation above the metacarpophalangeal joint. His right amputated and left intact hands were scanned with a three-dimensional scanner, and the left-hand image was rotated to the right side to design the right thumb prosthesis. The designed prosthesis was printed with a three-dimensional printer using the fused filament fabrication output system. The Jebsen-Taylor hand function test and Box and Block Test scores improved after application of the prosthesis. Most Quebec User Evaluation of Satisfaction with Assistive Technology results were "very satisfied," and most Orthotics and Prosthetics Users' Survey results were "very easy." Preparing the prosthesis made by three-dimensional scanner and three-dimensional printer was faster and cheaper than preparing a conventional prosthesis. Clinical relevance Using three-dimensional scanning and printing technique, we can easily produce specifically shaped finger prostheses for specific movements in amputated patients with low cost.

Background: An increasing number of reconstructive surgeons are using modern imaging technologies for preoperative planning and intraoperative surgical guidance. Conventional imaging modalities such as CT and MRI are relatively affordable and widely accessible and offer powerful functionalities. In the first of a two-part series, we evaluate established three-dimensional (3D) imaging and printing techniques based on CT and MRI used in plastic and reconstructive surgery. Method: A review of the published English literature dating from 1950 to 2017 was taken using databases such as PubMed, MEDLINE®, Web of Science and EMBASE. Result: In plastic and reconstructive surgery, the most commonly used, free software platforms are 3D Slicer (Surgical Planning Laboratory, Boston, MA, USA) and OsiriX (Pixmeo, Geneva, Switzerland). Perforator mapping using 3D-reconstructed images from computed tomography angiography (CTA) and magnetic resonance angiography (MRA) is commonly used for preoperative planning. Three- dimensional volumetric analysis using current software techniques remains labour-intensive and reliant on operator experience. Three-dimensional printing has been investigated extensively since its introduction. As more free open-source software suites and affordable 3D printers become available, 3D printing is becoming more accessible for clinicians. Conclusion: Numerous studies have explored the application of 3D-rendered conventional imaging modalities for perforator mapping, volumetric analysis and printing. However, there is a lack of comprehensive review of all established 3D imaging and printing techniques in a language suitable for clinicians.

Objective: To investigate reduction and fixation of complex acetabular fractures using three-dimensional (3D) printing technique and personalized acetabular wing-plate via lateral-rectus approach. Methods: From March to July 2016, 8 patients with complex acetabular fractures were surgically managed through 3D printing personalized acetabular wing-plate via lateral-rectus approach at Department of Orthopedics, the Third Affiliated Hospital of Southern Medical University. There were 4 male patients and 4 female patients, with an average age of 57 years (ranging from 31 to 76 years). According to Letournel-Judet classification, there were 2 anterior+ posterior hemitransverse fractures and 6 both-column fractures, without posterior wall fracture or contralateral pelvic fracture. The CT data files of acetabular fracture were imported into the computer and 3D printing technique was used to print the fractures models after reduction by digital orthopedic technique. The acetabular wing-plate was designed and printed with titanium. All fractures were treated via the lateral-rectus approach in a horizontal position after general anesthesia. The anterior column and the quadrilateral surface fractures were fixed by 3D printing personalized acetabular wing-plate, and the posterior column fractures were reduction and fixed by antegrade lag screws under direct vision. Results: All the 8 cases underwent the operation successfully. Postoperative X-ray and CT examination showed excellent or good reduction of anterior and posterior column, without any operation complications. Only 1 case with 75 years old was found screw loosening in the pubic bone with osteoporosis after 1 month's follow-up, who didn't accept any treatment because the patient didn't feel discomfort. According to the Matta radiological evaluation, the reduction of the acetabular fracture was rated as excellent in 3 cases, good in 4 cases and fair in 1 case. All patients were followed up for 3 to 6 months and all patients had achieved bone union. According to the modified Merle D'Aubigné and Postel scoring system, 5 cases were excellent, 2 cases were good, 1 case was fair. Conclusions: Surgical management of complex acetabular fracture via lateral-rectus approach combine with 3D printing personalized acetabular wing-plate can effectively improve reduction quality and fixation effect. It will be truly accurate, personalized and minimally invasive.

ABSTRACTThe distribution of fibers in the composite (which takes into account both their locations and orientations) is one of the important factors that affect the mechanical properties of FRCs. However, this parameter depends on various factors during composite fabrication, and controlling the distribution of fibers in the produced material represents a significant challenge. In this study, the applicability of three-dimensional (3D) printing technique for controlling fiber distributions was evaluated. The fibers fabricated using a 3D printer were placed inside a mold to produce cementitious composites. Three-point bending tests were conducted and the results of the experiment were discussed.

Creating biophysically and biologically desirable porous scaffolds has always been one of the greatest challenges in tissue engineering (TE). Advanced additive manufacture (AM) methods such as three-dimensional (3D) printing techniques have established remarkable improvements in the fabrication of porous scaffolds and structures close in architecture to biological tissue. Such fabrication techniques have opened new areas of research in TE. Recently, it was shown that porous scaffolds which are mathematically designed by using triply periodic minimal surface (TPMS) pore geometry and fabricated through 3D printing techniques have remarkably high cell viability and mechanical strength when compared with conventional scaffolds. The enhanced cell adhesion, migration, and proliferation of TPMS-based scaffolds arise from the high surface area to volume ratio (SA/V ratio) that is a basic and fundamental concept of biology. Here, we report the design of multi-void TPMS-based scaffolds that dramatically increase the SA/V ratio of conventional TPMS scaffolds. Our findings suggest that the proposed novel design methodology can be applied to create a variety of computational models for prototyping and printing of biomimetic scaffolds and bioartificial tissues.

BackgroundThe purpose of this study was to explore the feasibility of ulnar groove plasty guided by a three-dimensional (3D) printing technique for treatment of moderate to severe cubital tunnel syndrome (CuTS) caused by elbow osteoarthritis.Material/MethodsPatients with moderate to severe CuTS secondary to osteoarthritis of the elbow were enrolled in our hospital from April 2015 to March 2018. Based on a previously proposed “elbow canal index”, a 1: 1 model of the elbow joint was printed using CT image data collected preoperatively. After computer-aided measurement, the standard for enlargement of the ulnar nerve groove was calculated and a personalized “trial model” was created by 3D reconstruction. After intraoperative exposure of the ulnar nerve sulcus, the proliferative osteoid was burred with a grinding drill, and the cubital enlargement was verified by the trial model. The ulnar nerve was decompressed and reincorporated into the enlarged cubital canal, and the Osborne ligament was zig-zag elongated and reconstructed.ResultsNone of the patients reported experiencing medial elbow instability, medial elbow pain, ulnar nerve subluxation, flexor-pronator weakness, or incision infection. There was significant improvement of the motor nerve conduction velocity, sensory nerve conduction velocity, two-point discrimination of the little finger, grip strength, pinch strength of the thumb and index finger, VAS score, and DASH score in this study (P<0.001).ConclusionsUlnar groove plasty guided by a 3D printing technique may be another effective treatment of moderate to severe CuTS caused by elbow osteoarthritis.

Method for visualizing the shear process of rock joints using 3D laser scanning and 3D printing techniques

Osteogenesis of 3D printed porous Ti6Al4V implants with different pore sizes.

Three-dimensional printing is a rapidly developing area of technology and manufacturing in the field of oral surgery. The aim of this study was comparison of presurgical models made by two different types of three-dimensional (3D) printing technology. Digital reference models were printed 10 times using fused deposition modelling (FDM) and digital light processing (DLP) techniques. All 3D printed models were scanned using a technical scanner. The trueness, linear measurements, and printing time were evaluated. The diagnostic models were compared with the reference models using linear and mean deviation for trueness measurements with computer software. Paired t-tests were performed to compare the two types of 3D printing technology. A P value < 0.05 was considered statistically significant. For FDM printing, all average distances between the reference points were smaller than the corresponding distances measured on the reference model. For the DLP models, the average distances in the three measurements were smaller than the original. Only one average distance measurement was greater. The mean deviation for trueness was 0.1775 mm for the FDM group and 0.0861 mm for the DLP group. Mean printing time for a single model was 517.6 minutes in FDM technology and 285.3 minutes in DLP. This study confirms that presurgical models manufactured with FDM and DLP technologies are usable in oral surgery. Our findings will facilitate clinical decision-making regarding the best 3D printing technology to use when planning a surgical procedure.

Objective To explore the application value of three-dimensional (3D) printing in skull base tumor resection. Methods Fourteen patients accepted resection of skull base tumors in our hospital from May 2016 to November 2017 were chosen in our study; before surgery, solid models of the tumors, having bones of the skull base, tumor tissues and main blood supply arteries, were established by 3D printing; resection was simulated in these models and the surgical approaches and surgical methods were determined accordingly. The disease history, preoperative and postoperative imaging data were analyzed retrospectively. Results The mean time for making a solid model of the tumors was 18.5 h, and the cost was about 5,000 Yuan. Postoperative CT and MR imaging showed that total excision was achieved in 8 patients, subtotal excision was achieved in 5 patients, and one with tumor of the jugular foramen achieved total excision of the intracranial tumor and subtotal excision of the extracranial tumor. One patient had large hemispheric infarction after operation and decompressive craniectomy was performed; the other 13 patients recovered well without serious complications or death. Conclusion The 3D printing technique can assist the preoperative simulation and formulation of skull base tumor resection, and improve the efficiency and safety of the operation. Key words: Three-dimensional printing; Tumor of base of skull; Tumor resection

Abstract

Frequency selective surface (FSS) is a spatial filter that has frequency selection characteristics for electromagnetic waves with different operating frequencies, polarization states and incident angles. At the same time, frequency selective surface has the advantages of simple structure and easy processing compared with the traditional filters. FSS have been investigated for many decades and extensively utilized in various applications. It can used in radar radomes to reduce the radar cross section (RCS) of an array antenna, as a reflector to transmit and reflect electromagnetic waves in different frequency bands. Normally, electromagnetic waves are incident at an oblique Angle onto the target surface. Therefore, the research of FSS absorbers with stable absorbing performance under oblique incidence has tremendous practical application value. This paper proposes a new design scheme for designing a FSS absorber with stable oblique incident response range from 0° to 70°. A single-square-loop array with lumped resistors and square patch printed on the dielectric substrate is proposed, and it exhibits a characteristic impedance matching for wide incident angles from 0° to 70°. The design scheme of the FSS layer under the condition of oblique incidence is introduced in detail, and the equivalent circuit is adopted to make the design clearer and more direct. The results show the absorption bands with oblique incident angles from 0° to 30°, 30° to 50°, and 50° to 70° reflection coefficients below –10 dB are 3.44 to 9.03 GHz, 4.49 to 9.06 GHz, and 4.87 to 8.96 GHz for TE polarization, respectively. The absorber proposed in this paper will contribute much to the development of ultra-wide-angle oblique incidence.

Experimental method for internal deformation measurement of 3D solids with embedded cracks based on 3D printing and digital speckle techniques

Three-dimensional (3D) printing is a versatile technique used for various tissue-engineering applications and regenerative medicine. Tissue engineering comprises three primary components used with the aim of restoring, maintaining, or replaceing organs. Three-dimensional printing techniques have significant capability in creating three-dimensional scaffolds for tissue engineering and employing variety of biomaterials for scaffold fabrication. Three-dimensional scaffolds have an important role in cellular attachment, proliferation, nutrient transportation and vascularization. This review aims to introduce 3D printing techniques in hard-tissue engineering (bones and teeth) and soft-tissue engineering (cardiovascular system, nerves, cartilage, liver, skin and trachea) including scaffolds, applications and recent advances.

Dynamic covalent bonds within polymer materials have been the subject of ongoing research. These bonds impart polymers, particularly thermosets, with capabilities for self-healing and reprocessing. Concurrently, three-dimensional (3D) printing techniques have undergone rapid advancement and widespread adoption. Since polymers are among the primary materials used in 3D printing, networks featuring dynamic covalent bonds have emerged as a prominent research area. This review outlines approaches for incorporating dynamic covalent bonds into polymers suitable for 3D printing and examines representative studies that leverage these chemistries in material design. Polymers produced using these strategies demonstrate both self-healing and reprocessability, primarily via bond-exchange (metathesis) reactions. In addition, we discuss how the type and amount of dynamic bonds in the network affect the resulting material properties, with particular emphasis on their mechanical, physical, and thermal performance. In particular, the introduction of dynamic covalent bonds seems to significantly improve the degree of anisotropy, which has been the limitation of 3D printing techniques. Finally, we compile recent applications for objects printed from polymers that include dynamic covalent bonds.