Cyrille Delage

A new custom made bioceramic implant for the repair of large and complex craniofacial bone defects

INTRODUCTION Neurosurgery and Maxillofacial Surgery Departments of Limoges University Hospital Centre have developed a new concept of a custom made ceramic implant in hydroxyapatite (HA) for the reconstruction of large and complex craniofacial bone defects (more than 25 cm(2)). MATERIALS AND METHODS The manufacturing process of the implants used a stereolithography technique that produces implants with three-dimensional shapes derived directly from the scan file of the patients skull without moulding or machining. Eight patients received 8 implants between 2005 and 2008. RESULTS The surgical procedure is simple and fast. The post-operative follow-up was 12 months. No major complications (infection or fracture of the implant) were observed. The cosmetic result was considered satisfactory by both patients and surgeons. CONCLUSIONS These new implants are well suited for reconstruction of large craniofacial bone defects (greater than 25 cm(2)) in adults and children over 8 years.

Ceramic Layer-By-Layer Stereolithography for the Manufacturing of 3-D Millimeter-Wave Filters

Three-dimensional (3-D) ceramic stereolithography has been developed and used to manufacture RF devices using periodic structures. To our knowledge, it is the first time that zirconia and high-performance Ba3ZnTa2O9 ceramics are used with that process to manufacture high unloaded quality factor resonant structures and bandpass filters working in the Ka-band. A theoretical study on the performances of periodic arrangements of high-permittivity structures has been carried out and has led to the manufacture of a high unloaded quality factor cavity and narrow three-pole filter (1% bandwidth) measured at a working frequency of 33 GHz

Narrow Ka Bandpass Filters Made Of High Permittivity Ceramic By Layer-By-Layer Polymer Stereolithography

Electromagnetic bandgap (EBG) concept is used to create cavity by dimensioning a variant cell (or defect) inside a 2D EBG material. Compact high unloaded Q cavity (Qu ~ 2500) and narrow two and three pole filters are designed in Ka band. They are manufactured by layer-by-layer stereolithography and made out of high permittivity yttria-stabilized Zirconia. Measurements of the three pole filter working at 33.45GHz exhibits an 1.05% bandwidth and an insertion loss of 1.7dB. These specifications are close to the theoretical values of 33GHz (1.5% shift in central working frequency) and 0.95% bandwidth

Innovative Shielded High

This letter presents a compact design of a shielded high unloaded Q dielectric resonator. The main interest of this work is the use of the three-dimensional stereolithography process to manufacture innovative ceramic radio frequency devices. Thus, a resonator, its support, and the surrounding cavity is manufactured in one part out of alumina by that process. The measured structure exhibits an unloaded Q of 3900 at 11.88GHz and is free of spurious modes over a 3-GHz range

Q

The finite element method is coupled with the topology gradient method for optimizing the shape of microwave components using a numerical model. The approach, which consists in minimizing a cost function with respect to the physical property of individual topological elements, is first described. Regarding given electrical specifications, the technique is applied for optimizing the distribution of dielectric material in 3D in order to improve the behavior of a classical dual-mode filter including a dielectric resonator.

Dielectric Resonator Made of Alumina by Layer-by-Layer Stereolithography

Innovative resonant cavities based on 2D and 3D Electromagnetic Band Gap crystal properties are presented in this paper. Their geometrical sizes and shapes have been designed and optimized in order to obtain satisfying electrical performances concerning the resonant frequency and the unloaded Q factor. A particular attention has been paid to the Input/Ouput feeding of the structures. The EBG crystals have been designed, optimized and manufactured in one monolithic piece with zirconia or alumina materials. Two specific 3D ceramic stereolithography processes have been developed. Experimental structures have been manufactured and successfully tested compared to the theoretical results.

Topology optimization applied to the design of a dual-mode filter including a dielectric resonator

The shape of ceramic components is optimized for designing microwave filters. The approach consists in optimizing the transfer function with respect to the distribution of dielectric material. Regarding a classical way of design, the technique is applied for both improving the filter performance and simplifying its implementation.

Electromagnetic band gap millimeter and sub-millimeter 3D resonators manufactured by ceramic stereolithography

A design technique based on a shape optimization strategy (topology gradient algorithm) and a 3D ceramic stereolithography process are described in this paper. Our goals are to propose innovative components in terms of electric performances and topologies, by using these two approaches together. Several components have been designed, manufactured and tested with success. An example is given for the design of microwave filters including dielectric resonators.

Topology optimization of microwave filters including dielectric resonators

A 3D Electromagnetic band gap layer-by-layer crystal is studied in the millimeter wave domain. It has been designed and manufactured by 3D ceramic stereolithography with the ceramic material called zircon. Its particular properties have been used to design a high unloaded quality factor cavity (structural defect) localized within this crystal. This cavity has been measured at 30.5 GHz to demonstrate the concept in the millimeter wave domain. This resonant defect has also theoretically been studied while considering a low loss ceramic material such as BZT. It shows that an unloaded Q close to 10 000 can be obtained at this frequency.