Takeo Nishikawa

Development of New Localized Surface Plasmon Resonance Sensor with Nanoimprinting Technique

A new localized surface plasmon resonance sensor fabricated by the nanoimprinting technique is presented. Nanoimprinting, one of the most important nanofabrication technologies, can produce stable nanopatterns on a substrate with high throughput. In this study, we apply this technique to the preparation of sensor chips for a low-cost and reliable biosensor. The optimal cross-sectional structure of the sensor chip was calculated by a two-dimensional finite-difference time domain (FDTD) simulation method. The sensor chip with the optimized structure was fabricated by nanoimprinting of the nanopatterned metal mold onto a UV-curable resin and subsequent sputtering of a thin gold film. Using this fabrication process, an extremely large number of sensor chips can easily be produced from a single metal mold with high accuracy and reproducibility. The characteristics of the fabricated sensor chips were evaluated by measuring their absorption spectra. The absorption peak due to the localized SPR could be observed, which was almost consistent with the simulation result. The sensitivity of this sensor chip was confirmed to be comparable with that of the standard localized SPR sensor under development. The low-cost, stable, high-sensitivity biosensors that can be constructed by the present process will generate practical protein chips and point-of-care chips, which are expected to become key diagnosis tools in the future

Localized Surface Plasmon Resonance Sensor Based on Fabricating Nano-period Structure for High Throughput by Polymer

To realize a low-cost sensor and a sensor chip, we propose a localized surface plasmon resonance (LSPR) sensor in which nano-imprinting technology is applied to produce periodic arrangements of metallic nanostructures; we also verify its utility. LSPR can concentrate electric fields in the vicinity of nano-order metal structures. Accordingly, the sensing depth can be localized, resulting in noise reduction. Furthermore, nano-imprinting can be applied inexpensively and with high accuracy to fabricate nano-patterned sensor chips in large quantities. This work involves the design of an original nano-period structure and the application of nano-imprint technology to the fabrication of a sensor chip. The result is a proposal for a biosensor that allows fabrication with both higher throughput and lower cost.

A Nanobiosensor Fabricated by Nanoimprinting Technology

A new biosensor with a high sensitivity and a low process cost is presented in this paper. Localized surface plasmon resonance generated inside the nanogrooves was verified to have a high sensitivity and this structure could be produced using a nano imprinting technology which realizes a high reproducibility and a mass-production. The present sensor had five times as high sensitivity as the conventional colloidal localized surface plasmon resonance sensor. And the detection of BSA antigen using the present sensor was attained in this research.

Highly Sensitive SPR Biosensor Based on Nanoimprinting Technology

Detection of biomolecular interactions is becoming more important as a technique to achieve rapid diagnoses of incipient diseases and preventive medical care. Among various detection techniques currently available (e.g., fluorometry, quartz crystal microbalance, etc.), surface plasmon resonance (SPR)-based biosensing has received much attention since it does not require any labelling of the analytes and enables high-throughput real-time sensing. The SPR technique allows very fast measurements of the order of several minutes, whereas conventional enzyme-linked immunosorbent assay (ELISA) methods are often lengthy processes. Recently, SPR-based biosensors have been extensively applied to analyses in biomedical (Vaisocherova et al., 2006), environmental (Dostalek et al., 2006), and food sciences (Ladd et al., 2006). In conventional SPR, the evanescent field penetrates into the metal surface by as much as ~300 nm (Stenberg et al., 1991, Homola, 2003). When the target analyte binds to the metal surface, changes in the local refractive index occur, which in turn causes the SPR angle to shift. However, the sensing of target molecules suffers due to unwanted noise factors such as the instability of the temperature and the change in the refractive index of the mobile phase. Thus, the “sensing depth” of conventional SPR is significantly larger than the range required for practical use such as in clinical diagnoses. In this paper, we demonstrate that the sensing depth of SPR can be controlled by producing a pattern of periodic metal nanogrooves on the sensor surface.

Development of Localized Surface Plasmon Resonance Sensor Based on Nanoimprinting Technology

This paper introduces a localized surface plasmon resonance biosensor fabricated by using nanoimprinting technology. The detection of a cancer marker (alpha-fetoprotein) by a desktop proto-model based on this principle is also presented.