A micro/nanofluidic device containing linearly arranged gold nanoparticles embedded in nanochannels was developed for highly sensitive and highly efficient surface-enhanced Raman spectroscopy (SERS). The Si nanochannel array was fabricated using a photolithography-based process. The nanochannel width was controlled from 100 to 400 nm. Synthesized particles of mean diameter 100 nm were arranged linearly in the nanochannels, using a nanotrench-guided self-assembly process. We developed a process for integrating linearly arranged nanoparticles and micro/nanofluidic components. The particle geometry provided significant Raman enhancement. Furthermore, efficient Raman analysis was possible by scanning a laser spot, because the particles were arranged in one direction. The fabricated structures were evaluated for SERS using 4,4$-bipyridine molecules at concentrations of 1 mM and 10 µM. The Raman peaks was obtained from a few hot spots. The Raman spectra showed that the molecule-specific Raman intensities were correlated with the number of hot spots in the nanochannel.

SUMMARY A micro/nanofluidic device containing linearly arranged gold nanoparticles embedded in nanochannels was developed for highly sensitive surface‐enhanced Raman spectroscopy (SERS). The Si nanochannel array was fabricated using a photolithography‐based process. Synthesized colloidal particles of mean diameter 100 nm were arranged linearly in the nanochannels, using a nanotrench‐guided self‐assembly process. The particle geometry provides significant Raman enhancement by matching the polarization direction of the incident light to the connection direction of the particles. The SERS spectrum was obtained from 1‐mM 4,4’‐bipyridine solution using the fabricated micro/nanofluidic SERS device. The directionally arranged particles showed the same polarization angle dependency as the simulated result. The molecule was detected from 10‐pM solution using the particle arrangement. We confirmed that the particle arrangement was appropriate for highly sensitive SERS.

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The ability t o make a prenatal diagnosis of duodenal atresia by real time ultrasonic scanning is described.The mother had developed polyhydramnios at 3 0 weeks of gestation, and ultrasonography showed two distended fluid-filled spaces within the fetal abdomen. Peristalsis-like movements of these spaces were observed by real time ultrasonic scanning.Amniofetography cleared demonstrated the absence of contrast medium in the gastrointestinal tract.The two fluid-filled cysts observed in the fetal upper abdomen and the peristalsis-like movement strongly suggest congenital duodenal atresia.