Guidelines for the fabrication of nanoscale light-emitting diode arrays (i.e., nanoLED arrays) based on patterned gallium nitride (GaN) with very small dimensions and pitches have been derived in this work. Several challenges during top-down LED array processing have been tackled involving hybrid etching and polymer-based planarization to yield completely insulated highaspect-ratio LED fin structures and support the creation of p-GaN crossing line contacts, respectively. Furthermore, simulations of the light emission patterns were also performed providing hints for enhancing the device designs. As a result, regardless of the required device processing optimization, the developed nanoLED arrays are expected to offer high potential as novel illumination sources in biomedical imaging and sensing applications (e.g., mini compact microscopes and wearable biological/chemical nanoparticle counters)

Our contribution focuses on humidity gas-sensing device formation of metal oxide materials such as BaTiO3 nanorods and TiO2-BaTiO3 nanotubes. Processing of humidity sensors based on BaTiO3 nanostructured materials, that can operate under severe environmental conditions is of great relevance due to their small size and small weight. As a result, these sensors possess high stability, fast response times and reproducibility. Furthermore, gas sensor properties are not only interesting in terms of device applications, but also pave the way to study in deep ionic and electronic conduction mechanisms in individual nano-based devices.

A compact lensless microscope comprising a custom-made LED engine and a CMOS imaging sensor has been developed for live-cell culture imaging inside a cell incubator environment. The imaging technique is based on digital inline-holographic microscopy, while the image reconstruction is carried out by angular spectrum approach with a custom written software. The system was tested with various biological samples including immortalized mouse astrocyte cells inside a petri dish. Besides the imaging possibility, the capability of automated cell counting and tracking could be demonstrated. By using image sensors capable of video frame rate, time series of cell movement can be captured.

A waveguide Bragg grating (WBG) can facilitate an adaptable method for glucose monitoring according to the optical properties of polymer materials. We propose the design and fabrication of a WBG for glucose monitoring. By exploiting glucose oxidase as the upper cladding, polydimethylsiloxane was used as the substrate, and polymethyl methacrylate was used as the core layer. We investigated the effects of the diffraction order, waveguide structure, and grating period on the reflected spectrum of the WBG. Finally, process reproducibility after long-term storage and the capability to eliminate background solution interference (to achieve more specific glucose detection) were evaluated. The experimental results showed that when the glucose concentration was in the range of [0, 3.6] mg/ml, as the glucose concentration increased, the wavelength decreased approximately linearly, with a sensitivity of approximately 242.9 pm/(mg/ml) in the range of 0–2.7 mg/ml, while maintaining good selectivity and stability. The WBG for glucose monitoring has the advantages of a large measurement range and high sensitivity. This approach facilitates the application potential of such polymer material-based WBG photonic sensors in wearable technology and realizes the measurement of human blood glucose.

A novel sensing concept was developed; namely solar diode sensor (SDS), based on the integration and correlation of complementary functionalities originating from multiple junctions in a singular nanostructure to enable self-sustained gas sensors working without any external power sources except solar light. In this work, the gas sensing and solar energy harvesting abilities of metal oxide semiconductors were utilized to deliver a self-generated sensing signal. The fabricated sensors, based on CdS@n-ZnO/p-Si nanoelements, were capable of detecting oxidising and reducing gases with reproducible response at room temperature by solely using solar illumination. A new sensing mechanism (change of open circuit voltage, V oc), in comparison to the well-known conductometric sensors (change of resistance, R), was demonstrated and explained in terms of gas-material surface interactions and the subsequent changes in the doping level (N D) of metal oxides, which is manifested in the variation of V oc at the n-ZnO/p-Si heterojunction diode. Furthermore, the generality of the concept was demonstrated by extending the new sensing approach to other systems such as thin-film based heterojunctions and core-shell radial heterojunctions. The here reported gas sensors are promising candidates for the development of a new generation of commercially appealing, technically feasible and easy to use self-powered gas sensor nanodevices.