Integrating optically, electrically, and thermo-mechanically disparate materials into a fiber drawn from a preform is enabling fiber devices with unique functionalities. We present two examples: directionality-controlled radial fiber lasers and all-in-fiber chemical sensors.

A new all-in-fiber trace-level chemical sensing approach is demonstrated. Photoconductive structures, embedded directly into the fiber cladding along its entire length, capture light emitted anywhere within the fiber's hollow core and transform it directly into an electrical signal. Localized signal transduction circumvents problems associated with conventional fiber-optics, including limited signal collection efficiency and optical losses. This approach facilitates a new platform for remote and distributed photosensing.

We demonstrate an in-fiber gas phase chemical detection architecture in which a chemiluminescent (CL) reaction is spatially and spectrally matched to the core modes of hollow photonic bandgap (PBG) fibers in order to enhance detection efficiency. A peroxide-sensitive CL material is annularly shaped and centered within the fiber's hollow core, thereby increasing the overlap between the emission intensity and the intensity distribution of the low-loss fiber modes. This configuration improves the sensitivity by 0.9 dB/cm compared to coating the material directly on the inner fiber surface, where coupling to both higher loss core modes and cladding modes is enhanced. By integrating the former configuration with a custom-built optofluidic system designed for concomitant controlled vapor delivery and emission measurement, we achieve a limit-of-detection of 100 parts per billion (ppb) for hydrogen peroxide vapor. The PBG fibers are produced by a new fabrication method whereby external gas pressure is used as a control knob to actively tune the transmission bandgaps through the entire visible range during the thermal drawing process.

Photoconductive structures (PCS), embedded directly into the fiber cladding and extending its entire length, capture light emitted by a chemiluminescent material reacting with peroxide vapor flowing through the fiber core, as reported by Yoel Fink and co-workers on page 6005. The PCS directly transform this emissive signal into an electrical signal, thus facilitating a new all-in-fiber platform for remote and distributed photosensing. Image: courtesy of Yan Liang.

Fabrication and characterization 8-nm-sized conjugated polymer nanoparticles (CPNs) and two-photon (2P) imaging of CPN labeled endothelial cells in a collagen-gel-based microfluidic device is described. CPNs exhibit super brightness and photostability comparable to quantum dots. The hydrophilicity and non-toxicity of CPNs enable long-term monitoring of cells in a tissue model, supporting CPNs' potential in biological and biomedical applications.

Light up my life: Stable, bright, conjugated-polymer nanoparticles (CPNs) show promise for fluorescence imaging of live cells. The cell-permeable CPNs are synthesized by a simple solvent exchange, and accumulate exclusively in the cytosol (see picture) without any noticeable inhibition of cell viability. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2007/z701991_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Sensitive and reliable monitoring of kinase activity was reported by using highly efficient fluorescence resonance energy transfer of conjugated polymer nanoparticles (CPNs) to a rhodamine labelled peptide substrate.

Fabrication, characterization, and application of poly(phenylene ethynylene) (PPE)/silica composite particles are described. PPE is a class of conjugated polymers, which has been used for various sensory materials. However, its hydrophobic nature makes its application difficult in the aqueous phase, especially for biological substance detection. In this report, we utilized non-aqueous soluble PPE, 15 nm of colloidal silica particles, and aminosilane to fabricate a biosensory platform. The resulting composite showed high aqueous compatibility, large surface area, high quantum efficiency, and versatile chemical modification including oligonucleotide coupling. By monitoring the fluorescence quenching of PPE, we could detect a quencher-labeled target oligonucleotide specifically. Stern–Volmer (SV) analysis showed different accessibility of fluorophores (PPE) to a quencher labeled target oligonucleotide. The accessibility of fluorophores and SV constant are determined to be 0.54 and 4.2×107M−1, respectively, from a modified SV plot. This method will broaden the capability of conjugated polymers for the sensitive detection of biological substances.