Publications by authors named "Ari Hokkanen"

This article presents the design, fabrication, and characterization of edge-coupled 1D optical phased arrays (OPAs) combined with collimating lenses. Our concept was tested with two OPAs having different collimation ranges. Both OPA designs have 3-μm waveguide spacing and the maximum beam steering range is about 30° based on wavelength tuning around 1550 nm.

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Article Synopsis
  • Polymer optical fibers (POFs) are lightweight and versatile, commonly used in networks and vehicles, but they are usually made from synthetic polymers that rely on nonrenewable resources.* -
  • Recent research focuses on creating biopolymeric optical fibers using materials like alginate and methylcelluloses, improving properties like mechanical strength, thermal stability, and optical performance for practical applications.* -
  • The new biopolymer fibers show impressive characteristics, such as high strain capacity and toughness, suitable for advanced uses including humidity sensing and biomedical applications, all while being environmentally friendly.*
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Efforts to engineer high-performance protein-based materials inspired by nature have mostly focused on altering naturally occurring sequences to confer the desired functionalities, whereas de novo design lags significantly behind and calls for unconventional innovative approaches. Here, using partially disordered elastin-like polypeptides (ELPs) as initial building blocks this work shows that de novo engineering of protein materials can be accelerated through hybrid biomimetic design, which this work achieves by integrating computational modeling, deep neural network, and recombinant DNA technology. This generalizable approach involves incorporating a series of de novo-designed sequences with α-helical conformation and genetically encoding them into biologically inspired intrinsically disordered repeating motifs.

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Energy efficiency in habitation spaces is a pivotal topic for maintaining energy sufficiency, cutting climate impact, and facilitating economic savings; thus, there is a critical need for solutions aimed at tackling this problem. One viable approach involves complementing active cooling methods with powerless or passive cooling ones. Moreover, considerable scope remains for the development of passive radiative cooling solutions based on sustainable materials.

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Optical fibers are a key component in modern photonics, where conventionally used polymer materials are derived from fossil-based resources, causing heavy greenhouse emissions and raising sustainability concerns. As a potential alternative, fibers derived from cellulose-based materials offer renewability, biocompatibility, and biodegradability. In the present work, we studied the potential of carboxymethyl cellulose (CMC) to prepare optical fibers with a core-only architecture.

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Flexible optoelectronic technologies are becoming increasingly important with the advent of concepts such as smart-built environments and wearable systems, where they have found applications in displays, sensing, healthcare, and energy harvesting. Parallelly, there is also a need to make these innovations environmentally sustainable by design. In the present work, we employ nanocellulose and its excellent film-forming properties as a basis to develop a green flexible photonic device for sensing applications.

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Article Synopsis
  • A high-throughput roll-to-roll (R2R) process is introduced for making foil-based PMMA chips with excellent optical quality, intended for identifying the mecA antibiotic resistance gene in Staphylococcus epidermidis.
  • R2R hot embossing is highlighted as an innovative method for creating polymer microfluidic devices, utilizing a heated embossing cylinder to shape the polymer foil.
  • Despite the potential for mass fabrication of these microfluidic chips for biological uses being recognized in the past, this study marks the first published research in this area.
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We describe successful long-term stimulation of human embryonic stem cell-derived cardiomyocyte clusters on thin-film microelectrode structures in vitro. Interdigitated electrode structures were constructed using plain titanium on glass as the electrode material. Titanium rapidly oxidizes in atmospheric conditions to produce an insulating TiO(χ) layer with high relative permittivity.

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Integrated solid-phase extraction-zone electrophoresis (SPE-ZE) device has been designed and fabricated on microchip. The structures were fabricated by using multiple layers of SU-8 polymer with a novel technique that enables easy alignment and high yield of the chips. SU-8 adhesive bonding has two major advantages: it enables bonding of high aspect ratio pillars and it results in fully SU-8 microchannels with uniform electrokinetic flow properties.

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Analysis of the beta-blockers oxprenolol, atenolol, timolol, propranolol, metoprolol, and acebutolol in human urine by a combination of isotachophoresis (ITP) and zone electrophoresis (ZE) was investigated. Methods were developed with a conventional capillary electrophoresis (CE) apparatus and a poly(methyl methacrylate) (PMMA) microchip system. With CE the separation of oxprenolol, atenolol, timolol, and acebutolol from a standard solution containing 5 microg/mL of each compound was accomplished by performing ZE with transient ITP.

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