Electrically Small Circularly Polarized UWB Intraocular Antenna System for Retinal Prosthesis.

OBJECTIVE: This paper presents the design of an electrically small circularly polarized (CP) 3 × 3 mm2 antenna system as an intraocular unit for retinal prosthesis application. METHODS: The system is operating in ISM and ultra-wideband (UWB) bands to target high programmability of retina stimulation and recording, respectively. The electrical dimensions, including the ground plane, are λ0/41 × λ0/41 × λ0/191. Physical limitations of the antenna are discussed based on Hansen and Collin's limitations. The proposed wire patch antenna exhibits wideband characteristics by combining multiple modes of the patch antenna in the presence of an interface PCB circuit. RESULTS: By loading polyimide encapsulated patch with stubs, dominant TM010 mode is combined with the higher order modes TM020-TM070 to exhibit wide -10 dB impedance bandwidth of 2-11 GHz. Annular rings and shorting pins in the ground plane provide CP radiation at 2.45, 5.8, and 8 GHz with 3-dB axial-ratio bandwidth of 0.3, 0.16, and 1.2 GHz, and far-field left hand circularly polarized (LHCP) gain of -18.4, -7.6, and -4.7 dBic, respectively, in broadside direction. A biocompatible antenna system is designed using Ansys HFSS in the presence of a detailed multilayer canonical eye model. Additionally, it is examined in an anatomical HFSS head model. Near and far-field electric field distribution is studied along with peak 1-g average specific absorption rate (SAR) calculations. CONCLUSION: The proposed antenna is fabricated, and the performance, including coupled power from an external antenna, is measured in a custom made eye model including head phantom. A reasonable agreement is obtained between simulated and measured results. SIGNIFICANCE: To generate an artificial vision, image perception capability could be improved with implantable UWB communication systems that feature particularly high data-rate and small size.

Nanosystems as modulators of intestinal dapsone and clofazimine delivery.

The aim of this work was to assess the feasibility of drug nanosystems combination for oral therapy of multibacillary leprosy. The anti-leprotic drugs dapsone (DAP) and clofazimine (CLZ) were incorporated within polymeric nanosystems and studied per se and in combination. DAP was loaded in Eudragit L100 nanoparticles (NPs-DAP) while CLZ was loaded in (poly(lactic-co-glycolic acid) (NPs-CLZ). The nanosystems exhibited around 200 nm in size and a drug loading of 12% for each drug. In vitro cytotoxicity on intestinal Caco-2 cells revealed that after 8 h incubation, DAP alone and within NPs were not toxic up to 100 µg mL-1, while CLZ per se was toxic, reducing cell viability to 30% at 50 µg mL-1. Caco-2 exposed to the combination of NPs-DAP (100 µg mL-1) and NPs-CLZ (50 µg mL-1) exhibited 80% of viability. Caco-2 monolayer permeability assays revealed that DAP and CLZ in the nanosystems per se or in NPs-DAP/ NPs-CLZ combination crossed the intestinal barrier. No significant differences were observed between the single nanosystems or in combination with the apparent permeability values and the amount of permeated drug. Thus, the NPs-DAP/NPs-CLZ combination seems to be a promising platform to deliver both drugs in association, representing an important step towards the improvement of multibacillary leprosy therapy.

The application of biomedical engineering techniques to the diagnosis and management of tropical diseases: a review.

This paper reviews a number of biomedical engineering approaches to help aid in the detection and treatment of tropical diseases such as dengue, malaria, cholera, schistosomiasis, lymphatic filariasis, ebola, leprosy, leishmaniasis, and American trypanosomiasis (Chagas). Many different forms of non-invasive approaches such as ultrasound, echocardiography and electrocardiography, bioelectrical impedance, optical detection, simplified and rapid serological tests such as lab-on-chip and micro-/nano-fluidic platforms and medical support systems such as artificial intelligence clinical support systems are discussed. The paper also reviewed the novel clinical diagnosis and management systems using artificial intelligence and bioelectrical impedance techniques for dengue clinical applications.

Simultaneous assessment of contact pressure and local electrical coupling index using robotic navigation.

PURPOSE: Contact with cardiac tissue is a determinant of lesion efficacy during atrial fibrillation (AF) ablation. The Sensei®X Robotic Catheter System (Hansen Medical, CA) has been validated for contact force sensing. The electrical coupling index (ECI) from the EnSite Contact™ system (St. Jude Medical, MN) has been validated as an indicator of tissue contact. We aimed at analyzing ECI behavior during radiofrequency (RF) pulses maintaining a stable contact through the robotic navigation contact system. METHODS: In 15 patients (age, 59 ± 12) undergoing AF ablation, pulmonary vein (PV) isolation was guided by the Sensei®X System, employing the Contact™ catheter. RESULTS: During the procedure, we assessed ECI changes associated with adequate contact based on the IntelliSense® force-sensing technology (Hansen Medical, CA. Baseline contact (27 ± 8 g/cm(2)) ECI value was 99 ± 13, whereas ECI values in a noncontact site (0 g/cm(2)) and in a light contact site (1-10 g/cm(2)) were respectively 66 ± 12 and 77 ± 10 (p < 0.0001). Baseline contact ECI values were not different depending on AF presentation (paroxysmal AF, 98 ± 9; persistent AF, 100 ± 9) or on cardiac rhythm (sinus rhythm, 97 ± 7; AF,101 ± 10). In all PVs, ECI was significantly reduced during and after ablation (ECI during RF, 56 ± 15; ECI after RF, 72 ± 16; p < 0.001). A mean reduction of 32.2% during RF delivery and 25.4% immediately after RF discontinuation compared with baseline ECI was observed. CONCLUSIONS: Successful PV isolation is associated with a significant decrease in ECI of at least 20 %. This may be used as a surrogate marker of effective lesion in AF ablation.