Tomohiro Yamada

Battery-less wireless communication system through human body for in-vivo healthcare chip

This paper proposes a battery-less wireless communication system for in-vivo healthcare chip. We measured attenuation characteristics through a human body equivalent for six frequencies. Measured attenuation of 13.56 MHz is 47 dB through 15 cm thickness of human body equivalent. It is too difficult to use the usual modulations under such low power consumption. Then, we implemented the proposed system using the 13-56 MHz band with pulse interval modulation (PIM). In the simulated result, 16 mV of output voltage can be obtained at the outside receiver when coupling factor is 0.1. We also investigate antenna structure, and a tablet structure is suitable for the proposed system.

Seebeck Effects and Electronic Thermal Conductivity of IV-VI Materials

Theoretical calculations of the Seebeck coefficient and electronic thermal conductivity of general materials such as metals, semiconductors, and quantum structures are described, and the dependence of the Seebeck coefficient on doping level and temperature is discussed for lead-salt materials. Experimental Seebeck coefficient was measured for PbS films and the value agreed well with the theoretical value, indicating a high thermoelectric performance comparable to that of PbTe. The temperature dependence of electronic thermal conductivity is also discussed for lead salts. It is shown that minority carriers in the narrow-gap semiconductor significantly affect electronic thermal conductivity, and electronic thermal conductivity at high temperatures can be reduced by high-level doping.

Localized Surface Plasmon Resonant Metal Nanostructures as Refractive Index Sensors

The sensitivities of localized surface plasmon resonant sensors can be improved by changing the shape, size, and arrangement of nanosized metal dots on a substrate. In this study, we fabricated nanosized gold structure arrays on a silica substrate by electron beam lithography combined with a liftoff process, and studied their performance as refractive index sensors. We found that the sensitivity of single gold square dot arrays increases with the pitch while the absorbance decreases. On the other hand, both the sensitivity and absorbance of twin gold square dot arrays increase as the gap distance decreases for a particular incident polarization. We discuss the sensitivity of these structures for practical sensor applications.

In Vivo Batteryless Wireless Communication System for Bio-MEMS Sensors

We propose a batteryless wireless communication system for in vivo healthcare chips. The system uses inductive coupling at 13.56 MHz with internal and external coils, and employs pulse interval modulation (PIM) to endure the large attenuation in the human body. A wireless communication circuit is presented in this paper, and 16 mV of output voltage can be obtained at the external receiver. The antenna coil structure is investigated, and it is found that a tablet structure is suitable for the proposed system.

RF attenuation characteristics for in vivo wireless healthcare chip

We investigate a wireless communication system for an in vivo healthcare chip. In this paper, we present measured attenuation characteristics through the human body at several frequencies. In the measurement, we use physiological saline and fresh meat instead of a real human body. From the measured results, we found that 13.56 MHz has an attenuation of 47 dB and is suitable for the proposed system.

Metastable-Atom Auger Deexcitation Spectroscopy of Clean and Oxygen-Covered Si(111) Surfaces

The energy distribution of electrons emitted from clean and oxygen-covered Si(111) surfaces upon impact of metastable He*atoms was measured. The metastable deexcitation at the clean Si(111) surface was shown to occur predominantly via Auger deexcitation mechanism: He*+S→He+S++e- (S: surface). The adsorption process was monitored by this technique with a high sensitivity to the outermost atomic layer. Differences between the present metastable-atom deexcitation spectra and previous photoemission spectra are discussed.

in-vivo Wireless Communication System for Bio MEMS Sensors

Bio sensors have been developed using bio MEMS technology as a key device of μ-TAS (micro-Total Analytical System) [1]. This paper proposes an in-vivo wireless communication system to extend an application of the μ-TAS. The proposed system provides a small-size and battery-less wireless communication through human body as shown in Fig.1. It was implemented into 1.8mm chip, and it can realize an interactive sensing of everywhere in human body by swallowing or implanting into human body. The crucial problem of the in-vivo wireless communication is very large attenuation of human body. In this paper, we report measured attenuation characteristics of human body and an antenna coil structure for the wireless communication chip.

Near field communication chip using PIM for bio MEMS sensors

This paper presents a small-size wireless communication system for bio MEMS sensors, which uses the near field communication of 13.56MHz with Pulse Interval Modulation (PIM). In simulated result, 16mV of output voltage can be obtained at the outside receiver when coupling factor is 0.1.