Photofabrication Techniques Research Articles

Photofabrication of Highly Transparent Platinum Counter Electrodes at Ambient Temperature for Bifacial Dye Sensitized Solar Cells

Platinum (Pt) counter electrodes (CEs) have consistently shown excellent electrocatalytic performance and holds the record of the highest power conversion efficiency (PCE) for dye-sensitized solar cells (DSSCs). However, its use for large-scale production is limited either by high temperature required for thermal decomposition of its precursor or by wastage of the material leading to high cost or sophisticated equipment. Here, we report a novel photofabrication technique to fabricate highly transparent platinum counter electrodes by ultraviolet (UV) irradiation of platinic acid (H2PtCl6.6H2O) on rigid fluorine-doped tin oxide (FTO) and flexible indium-doped tin oxide (ITO) on polyethylene terephthalate (PET) substrates. The photofabrication technique is a facile and versatile method for the fabrication of Pt CEs for dye sensitized solar cells (DSSCs). The photofabricated Pt CEs were used to fabricate bifacial DSSCs with power conversion efficiencies (PCEs) attaining 7.29% for front illumination and 5.85% for rear illumination. The highest percentage ratio of the rear illumination efficiency to the front illumination efficiency (ηR) of 85.92% was recorded while the least ηR is 77.91%.

Multilayered receive coil produced using a non-planar photofabrication process for an intraluminal magnetic resonance imaging

An intraluminal probe coil is a promising signal detecting technique in magnetic resonance imaging (MRI) for small pathological lesions: it may allow acquisition of relatively high resolution images while maintaining similar signal-to-noise ratio (SNR) compared with external coils. In the present work, multilayered, saddle-shaped intraluminal coils with outer diameters of approximately 2mm were fabricated using a newly developed non-planar photofabrication technique. Single-, double- and quadruple-layered coils suitable for side-view scanning were prototyped and evaluated in terms of spatial resolution and SNR at 1.5T. The coils generated intraluminal MR images with sufficient SNR and spatial resolution.

3D Photo-Fabrication for Tissue Engineering and Drug Delivery

The most promising strategies in tissue engineering involve the integration of a triad of biomaterials, living cells, and biologically active molecules to engineer synthetic environments that closely mimic the healing milieu present in human tissues, and that stimulate tissue repair and regeneration. To be clinically effective, these environments must replicate, as closely as possible, the main characteristics of the native extracellular matrix (ECM) on a cellular and subcellular scale. Photo-fabrication techniques have already been used to generate 3D environments with precise architectures and heterogeneous composition, through a multi-layer procedure involving the selective photocrosslinking reaction of a light-sensitive prepolymer. Cells and therapeutic molecules can be included in the initial hydrogel precursor solution, and processed into 3D constructs. Recently, photo-fabrication has also been explored to dynamically modulate hydrogel features in real time, providing enhanced control of cell fate and delivery of bioactive compounds. This paper focuses on the use of 3D photo-fabrication techniques to produce advanced constructs for tissue regeneration and drug delivery applications. State-of-the-art photo-fabrication techniques are described, with emphasis on the operating principles and biofabrication strategies to create spatially controlled patterns of cells and bioactive factors. Considering its fast processing, spatiotemporal control, high resolution, and accuracy, photo-fabrication is assuming a critical role in the design of sophisticated 3D constructs. This technology is capable of providing appropriate environments for tissue regeneration, and regulating the spatiotemporal delivery of therapeutics.

Reflective Microoptical Element Array Fabricated by Photofabrication Technique

The authors present reflective microoptical element arrays fabricated by a photofabrication technique. The three-dimensional base of the microoptical element array is photofabricated by exposing photopolymerizable resin to a light beam through a grayscale mask. Reflective film on the photopolymerized base of the optical element is introduced to prevent serious problems in photofabricated refractive optical elements, such as when the optical characteristics of the elements fundamentally depends on the spectroscopic property of the material of the photofabricated optical element. The relationship between the pixel value in the grayscale bitmap image used for making the grayscale transparency mask and the cure depth of the photofabricated base is experimentally clarified for a photopolymerizable resin. 15×15 unit convex and concave micromirror arrays, in which each optical element has a diameter of 930 µm, have been batch fabricated. The focusing capability of the fabricated concave micromirror array is demonstrated.

Reflective Optical Element Fabricated by Photofabrication Technique Using A Photographic Film

Reflective Optical Element Fabricated by Photofabrication Technique Using A Photographic Film

Fabrication of Optical Components and Modules Using Photo-fabrication Technique

We describe optical components and optical modules using a photofabrication technique to demonstrate applicability of the technique for optical purposes. A thick plate and a prism were fabricated to study fabric characteristics. Examples of optical modules implemented by the photofabrication technique are a beam expander and an interferometer baseplate.

薄膜フラックゲート磁気センサの試作・評価

We fabricated a thin-film ring-core fluxgate sensor, using photofabrication techniques. The sensor consists of a perm- alloy ring-core, an excitation coil, and a differential pick-up coil. The two coils are wound round the core. The core is 4.24 mm in diameter, 160μm in width, and 1.5,μm in thick- ness. When the sensor is operated in a feedbackloop, the magnetic sensitivity is about 0.42 V/μT at an excitation frequency of 500 kHz, and a noise level of 1 nT/√Hz is estimated at 25°C and 100 Hz. This magnetometer system has good linearity for a magnetic field in the range from -26μT to 26μT. The magnetic sensitivity and the fluctuation of the zero point are independent of the tempera- ture in the range from -20°C to 65°C.

Further investigations of red cell deformability with nickel mesh

Although the filtration method has been widely employed in red cell deformability studies, the structural irregularity of the pores of a Nuclepore polycarbonate membrane has always been a major problem. Anegawa, T. et al. (Clin. Hemorheol., 7, 1987) obtained a higher reproducibility with the filtration method using a newly designed thin metal film with pores engraved by the photofabrication technique. We further studied the pressure - flow rate relationship of red cell suspension employing this nickel mesh. The filtration of red cell suspensions through the nickel mesh was not influenced by leukocytes contamination or added leukocytes up to a leukocyte count of 250 cells/mm3 within an experimental limitation. On the other hand, the flow was greatly influenced by leukocytes contamination when the polycarbonate membrane was used. The nickel mesh was found to be useful in detecting major determinants of red cell deformability, such as cell geometry and internal cellular viscosity, and in detecting abnormalities of red cell deformability in a patient with microangiopathic hemolytic anemia. In conclusion, the present study clearly shows that the nickel mesh is preferable for investigating red cell deformability to the polycarbonate membrane from a quantitative point of view. This material should contribute to the physiologic and clinical investigation of red cell deformability.

Fabrication of non-uniformly excited wide-band ultrasonic transducers

The plane and edge wave model of the action of an ultrasonic transducer has been used to predict that improved short-pulse, wide-band transducers could be produced by varying the excitation of the transducer elements as a function of the distance from its centre. The form of variation required has been determined by computer modelling and the means of achieving it was investigated experimentally. Photofabrication techniques based on those used in integrated circuit technology using photoresist for photoetching have been adapted to cope with the metallized surfaces of piezoelectric ceramics. Some examples of non-uniform transducers have been made and tested. When interrogating small targets, these transducers are shown to be as sensitive as conventional, uniformly-excited, short-pulse transducers, but with lateral resolution as much as an order of magnitude better. Compared with conventional focussed transducers the non-uniform wide-band transducers have a greatly increased depth of field.

Solving manufacturing problems by combining photofabrication with surface treatment and finishing techniques

SummaryThe subject of this paper is the utilisation of photofabrication techniques and surface treatment and finishing for the production of functional engineering components and decorative articles.Photofabrication is the term given to manufacturing methods employing photographic and photoresist technologies to produce stencil patterns on substrates which are then utilised to form components. These components maybe formed by photochemical machining (PCM), photoforming or associated processes.Surface treatment and finishing techniques include the processes of electroplating, anodising, electropolishing and various coating procedures using enamels, lacquers, paints and plastics.

Optical scales, reticles, gratings, masks, and standards

Photofabrication techniques using positive photoresists, developed for the quantity production of theodolite circular scales, have been adapted to making master chrome masks for photoetching moire fringe radial diffraction gratings. Diamond stylus wear, or chipping of the diamond tip, on a precision surface measuring instrument is difficult to detect and can cause incorrect surface texture measurements. A stylus wear standard was developed, and fabrication problems were solved by the anisotropic etching of a silicon slice using a chrome mask and photoresist. An essential feature of this process was precise orientation of the mask with a crystal cleavage plane. Experience gained suggests the means for quantitative quality control of diamond tools used for micromachining.

Flexible printed-circuit probe for electrophysiology

Photofabrication techniques have been used to produce a nickel-iron microelectrode array on Kapton film specifically designed for biological implantation. The probe is 2·5 mm×2 mm and carries four tissue terminals, each 2 μm in width. Both spontaneous and evoked potentials have been recorded from frog sciatic nerve. Developmental possibilities for the probe are fully discussed.