Cases / Results

The three-dimensional (3D) imaging by magnetic resonance force micro-scopy (MRFM) based on electron spin resonance (ESR) measurement is demonstrated at room temperature. For a microsample containing radicals, the 3D force distribution was obtained using a custom-made Si nano-wire and a permanent magnet. This result contributes to improving the long scanning time and achieving the high sensitive and wide range measurement.

The fabrication and evaluation of a microchannel with thin Si windows and a trapping structure for injected liquid samples is demonstrated. East cells and latex particles were observed using a scanning electron microscope (SEM) under vacuum.

Supercapacitor electrodes, composed of vertically-oriented graphene (VG) and MnO2, are synthesized on native SiO2-passivated silicon wafers. The VG layers with a thickness of ~3 μm are deposited directly on the substrates. The specific capacitance as high as 470.80 mF/cm2 at 20 mV/s is achieved with the increasing loadings of MnO2. The original retention of 99.29% after 5000 cycles demonstrates the excellent cycling stability, which is ascribed to the strong bonds between VG/SiO2/Si and MnO2/VG.

An actuator with large displacement is beneficial for camera shake compensation, but conventional MEMS electrostatic actuators are unable to achieve a displacement more than hundreds of µm. We, therefore, developed a magnetic actuator with a large displacement of 200 µm using soft springs of parylene and magnets embed in a Si substrate.

By moving the components of metamaterials by microactuators, it is possible to realize a “MEMS metamaterials” that has both the unique optical characteristics of the metamaterials and dynamic tunability. We have developed a transmittance tunable filter by incorporating a microactuator into an electromagnetically induced transparency (EIT) metamaterial that responds in the terahertz band and controlling the gap between the dipoles and quadrupoles that makes up the EIT metamaterial. It is expected to be applied to terahertz wave control, which plays an important role for next-generation wireless communication (Beyond 5G/6G).

If the dielectric layer that constitutes metal-dielectric-metal (MIM) metamaterials is an air gap, it is possible to construct “movable metamaterials” in which the thickness of the dielectric layer changes due to force. We have developed an optical force sensor that can measure the force applied on the diaphragm by measuring the resonance peak shift seen in the reflection spectrum. This sensor can achieve higher sensitivity than the conventional Fabry–Pérot interferometric optical force sensor.

In order to improve the performance, integration, and flexibility of flexible devices, we have conducted research on hetero-integration of heterogeneous device chiplets into a flexible substrate using compression-molding-based fan-out wafer-level package (FOWLP) technology. In this study, for the purpose of SpO2 monitoring by photo plethysmography (PPG), we realized high-precision assembly of tiny chips and successfully integrated μLEDs, driver circuits, and photodiodes in a PDMS.

In order to realize spiking neural networks as hardware, devices that can reproduce neuronal functions are necessary. In this study, we fabricated a nonvolatile tunnel FET memory that can operate at both large memory capacity and low operation voltage, and showed that it can reproduce spike timing-dependent plasticity, one of the neuronal functions.

“Plasmonic color filters” that use metal nanostructures have various advantages over conventional color filters that use pigment absorption, such as the ability to collectively form filters with various color characteristics with a thickness of only a few tens of nanometers. By manufacturing plasmonic color filters on a photodiode array, we have developed a compact spectrometer that is miniaturized compared to conventional spectrometers and is small enough to fit on a fingertip.

A silicon micromechanical resonator as a resonant temperature sensor and microchannel were fabricated in a microfluidic chip, which can measure the temperature of small objects in solutions. The cavity around the resonator can be evacuated to vacuum without interfering with the liquid-filled microchannel.

“Silicon waveguide” is an elemental technology of optical circuits that will play an important role for next-generation optical communication. We have developed an optical switch that switches the optical path by driving the silicon waveguide with a microactuator and controlling the optical coupling efficiency with the microdisk resonator.

STT-MRAM is a magnetoresistive change memory that uses a data rewriting technique called spin transfer torque (STT), but it has the problem of low thermal endurance. In this study, we succeeded in three-dimensional integrated STT-MRAM using Through-Si Via (TSV) by suppressing the thermal load due to the integration process.

“Photonic crystal” is a fine periodic structure with the same size as the wavelength of light and has the function of blocking and confining light. We have developed a reflectance-variable filter that controls the optical coupling efficiency of a nano-optical resonator and controls the light blocking characteristics by controlling the position of the photonic crystal with high accuracy using a microactuator.