Distributed Element Designs for a Wireless System

A prototype binary frequency shift keying (BFSK) RF link operating in the 2.4 GHz ISM band was identified as a need for a potential undergraduate engineering laboratory activity. This system would be used to showcase various RF circuit engineering principles and techniques such as controlled trace impedances, frequency mixing, voltage-controlled oscillators, distributed element filters, and power splitters. This investigation focused on designing a prototype system that put a priority on ease of measurement and circuit tuning to help foster a more hands on approach. Each major circuit element was broken into separate PCBs to increase the modularity of the design and allow for each of them to be measured independently of the system. All schematic capture and layout was performed in Altium Designer. The RF system was able to transmit up to 60 cm with an input power of 0 dBm without any dedicated amplification. The use of a distributed element 2.4 GHz bandpass filter was used as an opportunity to investigate the impact on filter performance that different substrates and filter subtypes had on the overall filter design. Four substrates of various thickness, 50 to 62 mils, and dielectric constants, εr = 3.55 to 10.2, were used for stepped impedance, edge-coupled, hairpin, and elliptic filters. All 16 of the filters were designed using Genesys 2015, laid out using Altium 2015, and routed on a LPKF ProtoMat S103 circuit board router. It was found that the stepped impedance and elliptic filters required traces less than 2 mils wide which are not easily manufacturable. Only the edgecoupled and hairpin designs were built. Out of these eight designs, the substrates with the lower dielectric constants performed the closest to their simulated results. However, this could have been due to unanticipated challenges when routing the higher dielectric materials that was not present for the lower dielectrics

Patient specific ankle-foot orthoses using rapid prototyping

Background Prefabricated orthotic devices are currently designed to fit a range of patients and therefore they do not provide individualized comfort and function. Custom-fit orthoses are superior to prefabricated orthotic devices from both of the above-mentioned standpoints. However, creating a custom-fit orthosis is a laborious and time-intensive manual process performed by skilled orthotists. Besides, adjustments made to both prefabricated and custom-fit orthoses are carried out in a qualitative manner. So both comfort and function can potentially suffer considerably. A computerized technique for fabricating patient-specific orthotic devices has the potential to provide excellent comfort and allow for changes in the standard design to meet the specific needs of each patient. Methods In this paper, 3D laser scanning is combined with rapid prototyping to create patient-specific orthoses. A novel process was engineered to utilize patient-specific surface data of the patient anatomy as a digital input, manipulate the surface data to an optimal form using Computer Aided Design (CAD) software, and then download the digital output from the CAD software to a rapid prototyping machine for fabrication. Results Two AFOs were rapidly prototyped to demonstrate the proposed process. Gait analysis data of a subject wearing the AFOs indicated that the rapid prototyped AFOs performed comparably to the prefabricated polypropylene design. Conclusions The rapidly prototyped orthoses fabricated in this study provided good fit of the subject's anatomy compared to a prefabricated AFO while delivering comparable function (i.e. mechanical effect on the biomechanics of gait). The rapid fabrication capability is of interest because it has potential for decreasing fabrication time and cost especially when a replacement of the orthosis is required

Cannabidiol in the acute phase of febrile infection-related epilepsy syndrome (FIRES)

Febrile infection-related epilepsy syndrome (FIRES) is a prolonged refractory status epilepticus (SE) that develops among healthy individuals after a febrile infection. FIRES treatment is challenging due to its poor response to antiseizure medications (ASMs) and anesthetic drugs. The use of cannabidiol (CBD) as an adjunctive treatment has been suggested, albeit data about its role in the acute phase is lacking. This report describes the use of purified CBD in the acute phase of two pediatric cases of FIRES and their long-term outcome. Both children were treated with several ASMs, immunomodulators, anesthetics, and nonpharmacological treatment (ketogenic diet). CBD was administered, as an adjunctive treatment, through nasogastric tube about 30 days after onset. SE resolved within 3 days of reaching the target dose and both were seizure-free for 1 year after. Although it is difficult to define the extent to which each previous therapy contributed to recovery, in both cases CBD therapy was a turning point, reinforcing its potential role as add-on treatment in the acute phase of FIRES

Adding functionality with additive manufacturing : fabrication of titanium-based antibiotic eluting implants

Additive manufacturing technologies have been utilised in healthcare to create patient-specific implants. This study demonstrates the potential to add new implant functionality by further exploiting the design flexibility of these technologies. Selective laser melting was used to manufacture titanium-based (Ti-6Al-4V) implants containing a reservoir. Pore channels, connecting the implant surface to the reservoir, were incorporated to facilitate antibiotic delivery. An injectable brushite, calcium phosphate cement, was formulated as a carrier vehicle for gentamicin. Incorporation of the antibiotic significantly (p=0.01) improved the compressive strength (5.8±0.7MPa) of the cement compared to non-antibiotic samples. The controlled release of gentamicin sulphate from the calcium phosphate cement injected into the implant reservoir was demonstrated in short term elution studies using ultraviolet-visible spectroscopy. Orientation of the implant pore channels were shown, using micro-computed tomography, to impact design reproducibility and the back-pressure generated during cement injection which ultimately altered porosity. The amount of antibiotic released from all implant designs over a 6hour period (<28% of the total amount) were found to exceed the minimum inhibitory concentrations of Staphylococcus aureus (16μg/mL) and Staphylococcus epidermidis (1μg/mL); two bacterial species commonly associated with periprosthetic infections. Antibacterial efficacy was confirmed against both bacterial cultures using an agar diffusion assay. Interestingly, pore channel orientation was shown to influence the directionality of inhibition zones. Promisingly, this work demonstrates the potential to additively manufacture a titanium-based antibiotic eluting implant, which is an attractive alternative to current treatment strategies of periprosthetic infections

Rolling polyhedra on a plane, analysis of the reachable set

The problem of dexterous manipulation of objects, i.e. of arbitrary relocation and reorientation of rigid bodies by action of some mechanism, is considered. We build upon previous results on the possibility of implementing dexterous “robot hands ” with few actuators, which can be afforded through the exploitation of nonholonomic rolling of regular surfaces. In this paper we focus on the manipulation of polyhedral objects, and prove a necessary and sufficient controllability–like result, which discloses some of the interesting aspects and perspectives of this problem.