Summary A new approach for body heat energy harvesting was proposed, and the theoretical performance has been demonstrated for wearable health care sensors as a target. One of the most important issues in the wearable system is a power supply. Humans keep their body temperature constant as long as they are alive. If we use thermal energy effectively, we could get the energy no matter when and where we go. However, thermal energy has hardly been used as power supply because thermoelectric conversion efficiency is very low. Quite different from the conventional thermoelectric device, the new approach uses rotation of turbine by stack effect. The driving force for the turbine is the pressure difference (ΔP) created by stack effect in a closed system. To obtain high performance, the device parameters are optimized by theoretical analysis. The obtained power density is 97.2 mW/cm3 when the outside air temperature is 277.15 K, and the device size is 5 mm × 2 mm × 10 mm. The energy density of the device is five or more times larger than that of a solar cell. The energy device can be assembled directly inside the various kind of wearable health care sensors. Therefore, the new approach for the body heat energy harvesting is a promising power supply means for the wearable system.

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A novel organic crystal, (-)-1-(4-dimethylaminophenyl)-2-(2-hydroxypropylamino)cyclobutene-3,4-dione (DAD), has been grown and its linear and nonlinear optical properties have been characterized. The DAD crystal belongs to a space group P1 with a large second-order nonlinear optical coefficient d11, which is measured by the Maker-fringe method to be 200 +or- 40 pm V-1 at a fundamental wavelength of 1.064 mu m.

A coexistence with normal and reverse scattering modes is demonstrated in a single liquid crystal (LC) cell by using a polymer stabilized effect. The homogeneously oriented or twisted LC cell containing a small amount of reactive mesogen is exposed with UV light under a suitable curing voltage application. A light scattering state is obtained and it becomes clear by applying voltage. The cell fabricated without the curing voltage shows a reverse mode property, that is, a transparent voltage off-state and the light scattering on-state. A driving voltage of the normal mode is almost the same as that of the reverse mode. A domain with the normal mode property is successfully fabricated in the reverse mode LC cell by two step UV exposures through a photomask with and without the curing voltage. Scattering and transparent patterns simultaneously turns to transparent and scattering states without electrode partitions.

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