Punctate Inner Choroidopathy: A Review

Punctate Inner Choroidopathy (PIC), an idiopathic inflammatory multifocal chorioretinopathy that predominantly affects young myopic women, appears to be relatively rare, but there is limited data to support accurate estimates of prevalence, and it is likely that the condition is under-diagnosed. The etiological relationship between PIC and other conditions within the 'white dot syndromes' group remains uncertain. We, like others, would suggest that PIC and multifocal choroiditis with panuveitis (MCP) represent a single disease process that is modified by host factors (including host immunoregulation) to cause the range of clinical phenotypes seen. The impact of PIC on the patient is highly variable, with outcome ranging from complete spontaneous recovery to bilateral severe sight-loss. Detection and monitoring has been greatly facilitated by modern scanning techniques, especially OCT and autofluorescence imaging, and may be enhanced by co-registration of sequential images to detect change over time. Depending on the course of disease and nature of complications, appropriate treatment may range from observation to systemic immunosuppression and anti-angiogenic therapies. PIC is a challenging condition where treatment has to be tailored to the patient's individual circumstances, the extent of disease, and the risk of progression

Miniature fluorescence sensor for quantitative detection of brain tumour

Fluorescence-guided surgery has emerged as a vital tool for tumour resection procedures. As well as intraoperative tumour visualisation, 5-ALA-induced PpIX provides an avenue for quantitative tumour identification based on ratiometric fluorescence measurement. To this end, fluorescence imaging and fibre-based probes have enabled more precise demarcation between the cancerous and healthy tissues. These sensing approaches, which rely on collecting the fluorescence light from the tumour resection site and its remote spectral sensing, introduce challenges associated with optical losses. In this work, we demonstrate the viability of tumour detection at the resection site using a miniature fluorescence measurement system. Unlike the current bulky systems, which necessitate remote measurement, we have adopted a millimetre-sized spectral sensor chip for quantitative fluorescence measurements. A reliable measurement at the resection site requires a stable optical window between the tissue and the optoelectronic system. This is achieved using an antifouling diamond window, which provides stable optical transparency. The system achieved a sensitivity of 92.3% and specificity of 98.3% in detecting a surrogate tumour at a resolution of 1 x 1 mm2. As well as addressing losses associated with collecting and coupling fluorescence light in the current remote sensing approaches, the small size of the system introduced in this work paves the way for its direct integration with the tumour resection tools with the aim of more accurate interoperative tumour identification

Punctate inner choroidopathy: A review

Punctate Inner Choroidopathy (PIC), an idiopathic inflammatory multifocal chorioretinopathy that predominantly affects young myopic women, appears to be relatively rare, but there is limited data to support accurate estimates of prevalence, and it is likely that the condition is under-diagnosed. The etiological relationship between PIC and other conditions within the 'white dot syndromes' group remains uncertain. We, like others, would suggest that PIC and multifocal choroiditis with panuveitis (MCP) represent a single disease process that is modified by host factors (including host immunoregulation) to cause the range of clinical phenotypes seen. The impact of PIC on the patient is highly variable, with outcome ranging from complete spontaneous recovery to bilateral severe sight-loss. Detection and monitoring has been greatly facilitated by modern scanning techniques, especially OCT and autofluorescence imaging, and may be enhanced by co-registration of sequential images to detect change over time. Depending on the course of disease and nature of complications, appropriate treatment may range from observation to systemic immunosuppression and anti-angiogenic therapies. PIC is a challenging condition where treatment has to be tailored to the patient's individual circumstances, the extent of disease, and the risk of progression

Flexible electronics: The next ubiquitous platform

Thin-film electronics in its myriad forms has underpinned much of the technological innovation in the fields of displays, sensors, and energy conversion over the past four decades. This technology also forms the basis of flexible electronics. Here we review the current status of flexible electronics and attempt to predict the future promise of these pervading technologies in healthcare, environmental monitoring, displays and human-machine interactivity, energy conversion, management and storage, and communication and wireless networks

Laser driven miniature diamond implant for wireless retinal prostheses

The design and benchtop operation of a wireless miniature epiretinal stimulator implant is reported. The implant is optically powered and controlled using safe illumination at near-infrared wavelengths. An application-specific integrated circuit (ASIC) hosting a digital control unit is used to control the implant\u27s electrodes. The ASIC is powered using an advanced photovoltaic (PV) cell and programmed using a single photodiode. Diamond packaging technology is utilized to achieve high-density integration of the implant optoelectronic circuitry, as well as individual connections between a stimulator chip and 256 electrodes, within a 4.6 mm x 3.7 mm x 0.9 mm implant package. An ultrahigh efficiency PV cell with a monochromatic power conversion efficiency of 55% is used to power the implant. On-board photodetection circuity with a bandwidth of 3.7 MHz is used for forward data telemetry of stimulation parameters. In comparison to implants which utilize inductively coupled coils, laser power delivery enables a high degree of miniaturization and lower surgical complexity. The device presented combines the benefits of implant miniaturization and a flexible stimulation strategy provided by a dedicated stimulator chip. This development provides a route to fully wireless miniaturized minimally invasive implants with sophisticated functionalities

Laser Driven Miniature Diamond Implant for Wireless Retinal Prostheses

AbstractThe design and benchtop operation of a wireless miniature epiretinal stimulator implant is reported. The implant is optically powered and controlled using safe illumination at near‐infrared wavelengths. An application‐specific integrated circuit (ASIC) hosting a digital control unit is used to control the implant's electrodes. The ASIC is powered using an advanced photovoltaic (PV) cell and programmed using a single photodiode. Diamond packaging technology is utilized to achieve high‐density integration of the implant optoelectronic circuitry, as well as individual connections between a stimulator chip and 256 electrodes, within a 4.6 mm × 3.7 mm × 0.9 mm implant package. An ultrahigh efficiency PV cell with a monochromatic power conversion efficiency of 55% is used to power the implant. On‐board photodetection circuity with a bandwidth of 3.7 MHz is used for forward data telemetry of stimulation parameters. In comparison to implants which utilize inductively coupled coils, laser power delivery enables a high degree of miniaturization and lower surgical complexity. The device presented combines the benefits of implant miniaturization and a flexible stimulation strategy provided by a dedicated stimulator chip. This development provides a route to fully wireless miniaturized minimally invasive implants with sophisticated functionalities

Thin film coil design considerations for wireless power transfer in flat panel display

Wireless power transfer is experimentally demonstrated by transmission between an AC power transmitter and receiver, both realised using thin film technology. The transmitter and receiver thin film coils are chosen to be identical in order to promote resonant coupling. Planar spiral coils are used because of the ease of fabrication and to reduce the metal layer thickness. The energy transfer efficiency as a function of transfer distance is analysed along with a comparison between the theoretical and the experimental results. © 2012 Materials Research Society

An all-diamond, hermetic electrical feedthrough array for a retinal prosthesis

The interface between medical implants and the human nervous system is rapidly becoming more and more complex. This rise in complexity is driving the need for increasing numbers of densely packed electrical feedthrough to carry signals to and from implanted devices. This is particularly crucial in the field of neural prosthesis where high resolution stimulating or recording arrays near peripheral nerves or in the brain could dramatically improve the performance of these devices. Here we describe a flexible strategy for implementing high density, high count arrays of hermetic electrical feedthroughs by forming conducting nitrogen doped nanocrystalline diamond channels within an insulating polycrystalline diamond substrate. A unique feature of these arrays is that the feedthroughs can themselves be used as stimulating electrodes for neural tissue. Our particular application is such a feedthrough, designed as a component of a retinal implant to restore vision to the blind. The hermeticity of the feedthroughs means that the array can also form part of an implantable capsule which can interface directly with internal electronic chips. The hermeticity of the array is demonstrated by helium leak tests and electrical and electrochemical characterisation of the feedthroughs is described. The nitrogen doped nanocrystalline diamond forming the electrical feedthroughs is shown to be non-cyctotoxic. New fabrication strategies, such as the one described here, combined with the exceptional biostability of diamond can be exploited to generate a range of biomedical implants that last for the lifetime of the user without fear of degradation

Vertical Ge-Si Nanowires with Suspended Graphene Top Contacts as Dynamically Tunable Multispectral Photodetectors

Numerous applications would be enabled by pixels for multispectral imaging whose spectral responses can be dynamically tuned and that can be potentially manufactured at low cost. Here, we show such a capability, by experimentally demonstrating arrays of vertically oriented germanium-silicon heterojunction nanowires with graphene top contacts. Our devices present opportunities for multispectral imaging because their responsivity spectra can be tailored by choice of nanowire radius for enhanced absorption at certain wavelengths across the visible to short-wave infrared. Importantly, these responsivity spectra can also be dynamically tuned by bias voltage. We demonstrate this experimentally by tuning the responsivity peak of a single pixel across the visible region by varying the bias voltage and by showing that this would allow red/green/blue channels to be reconstructed. This opens the exciting prospect of a single pixel that can resolve color (i.e., replacing the three red/green/blue pixels of traditional approaches) or even resolve several bands for multispectral imaging