Digital enzyme-linked immunosorbent assay (ELISA) is a single molecule counting technology and is one of the most sensitive immunoassay methods. The key aspect of this technology is to concentrate enzyme reaction products from a single target molecule in femtoliter droplets. On the other hand, we have developed a novel Digital ELISA that does not require droplets; instead, enzyme reaction products are concentrated using a tyramide signal amplification system. In this study, we present a method that enables the multiplex detection of proteins based on Droplet-free Digital ELISA. First, two types of paramagnetic beads immobilized with antibodies specific to different target proteins were incubated with a sample solution, and target proteins were captured on their specific beads. Then, these beads were labeled with horseradish peroxidase (HRP), and tyramide substrate reacted with HRP on beads, resulting in products of this reaction deposited on those beads. This signal amplification on beads makes it possible to count the number of labeled beads digitally. We used this approach to simultaneously detect IL-6 and HBs Ag with single molecule resolution. The obtained limit of detections were 0.1 pg/mL and 0.013 IU/mL, respectively. Our method has potential applications in simple in vitro diagnostic systems for simultaneous and high sensitive detection of protein biomarkers.

Luminal flow in a vascular network delivers nutrients and oxygen to cells in human bodies and applies mechanical stimuli to maintain vascular functions. Although many in vitro vascular models have been developed, there are no reports elucidating the effect of a long-term perfusion in a vascular network. Here, we report two types of microfluidic devices to investigate a vascular remodeling and long-term tissue culture in vitro. We observed formation of angiogenic spouts and a change of the volume of the vascularized tissue model in our microfluidic devices. Our method provides a new platform to study developmental biology with a long-term perfusion.

In this paper, we report on analytical results of terahertz (THz)-wave response of frame structures that support a thin film where metamaterial elements exist. Since the transmittance spectra of the metamaterial including the support frames differ from those of the metamaterial elements excluding the frames, investigation of influences of the frames on the measured spectra is important. A preliminary analysis revealed that the spectra of the metamaterial elements are partially recovered by compensating the measured spectra using time-domain transmittance waves of a bulk silicon-on-insulator wafer, from which the support frames are made. We experimentally demonstrate that the spectra of the support frames depend on the width, but not on the pitch, of the frames. Moreover, we show that a slab-type waveguide model can explain the interference between the support frames and the incident THz waves. The physical mechanism of THz response of support frames, which are clarified in this article, will be helpful to design thin-film type metamaterials.

This review provides the spintronic strain-gauge sensor (Spin-SGS) based on a magnetic tunnel junction (MTJ) with a high gauge factor in excess of 5000, which was realized by adopting a novel amorphous Fe-B-based sensing layer with high magnetostriction and low coercivity in a high magnetoresistance Mg-O barrier MTJ. This review also provides a demonstration of novel “Spintronic MEMS (Spin-MEMS) microphone,” in which a series of Spin-SGSs are integrated onto a bulk micromachined diaphragm. The Spin-MEMS microphone exhibits a signal-to-noise ratio (SNR) of 57 dB(A) due to the high strain sensitivity of the Spin-SGSs.

The author investigated gauge factors (Gf) of Cr-Al-N thin films in high temperature range. As a result, it was found that the thin film showed a uniform and high Gf of about 8 over the temperature range from -50℃ to around 350℃. It was considered that the films were able to be expected as high sensitive strain sensors to use in high temperature range.

In this paper, we propose a design approach for MEMS microphone that achieves SNR over 68 dB. Squeeze-film damping resistance was calculated for various diameter/pitch of acoustic holes arranged in backplate. Output noise level was estimated by equivalent circuit model. We show optimization method that considers capacitance change, process stability and mechanical robustness. Noise spectrum and SNR simulated by this method showed good agreement with experimental data. The results emphasize the importance of total optimization for MEMS-ASIC-package system. This design approach is expected to be applied to a variety of MEMS sensors that are susceptible to squeeze-film damping effect.

Near-infrared detectors by silicon based devices with large scale integration are very attractive for secure applications about image sensors. Beyond the silicon bandgap, we focus on PbS colloidal quantum dots (CQDs) and silicon integration. In this paper, we investigated fabrication processes of PbS CQDs and silicon hybrid IR detector. Temperature dependent photoluminescence of PbS CQDs thin films are measured and we found the bandgap of PbS CQDs do not change by various temperature. Optical response by a spectrometer were observed in 1550 nm range.

This paper addresses a capacitive MEMS hydrogen sensor using Pd based metallic glass for future hydrogen society. Firstly, we investigate PdCuSi as Pd based metallic glass (MG) and show this material is promising for capacitive MEMS hydrogen sensor. Secondly, we apply the Pd based MG to a hydrogen sensor having inverted T-shaped electrode. The sensor was fabricated by a surface micromachining process. We show that the fabricated hydrogen sensor exhibits hysteresis free and fast response property at room temperature.

MEMS post-process is now used to develop the ability of an LSI chip. In this paper, increasing of breakdown voltage of a standard CMOS LSI chip is mainly remarked. Especially, MEMS post-processed transistors are described. The technology enables us to use standard CMOS foundry-made transistors on a silicon-on-insulator (SOI) wafer. The key fabrication process is mesa isolation postprocessing that physically separates a series-connected transistor's body. The process is a combination of anisotropic and isotropic deep reactive ion etching (DRIE) with a single mask. The high-voltage switching circuit can be integrated with series-connected high-voltage PV cells and has the possibility of an on-chip MEMS driver in a self-powered IoT device.

For long-term culture of a single neuron, many astrocytes and a single neuron were co-cultured on both sides of a 1 µm thick silicon nitride membrane which has many microholes of 3 µm in diameter. After astrocytes were cultured on the back side of the membrane for 1 week, a neuron was seeded on the front side of the membrane of a microwell bottom and cultured for 5 weeks. By fluorescently staining VGLUT1 (vesicular glutamate transporter 1) which is localized at a presynaptic terminal, we found that the number of synapses formed by a single neuron drastically increases within the first 2 weeks and keeps high values for weeks afterward.