Core body temperature, which is the temperature inside the body, is a useful biological indicator for understanding changes in various physical activities due to its characteristics of being insensitive to external disturbances. However, the gold standard measurement methods require inserting probes in the body, which is highly invasive and unsuitable during activity. Conversely, a patch-type sensor that estimates core body temperature from heat flow changes near the skin surface has been attracting attention as a suitable method during activity. However, its practical challenge has been to improve robustness to environmental changes. Recently, we have solved this problem by improving the conventional measurement probe. Nevertheless, the weight reduction of the measurement probe has been an additional challenge. Here, we focused on the probe cover, which had previously been identified as a significant obstacle to weight reduction. We investigated the potential of applying a typical lightweight structure, such as a hollow or stepped structure, to the probe cover in order to achieve both weight reduction and high accuracy of the measurement probe.

Microfluidic droplets can be used as a field of chemical reaction to decrease reagents and reduce reaction time, and they offer great advantage for high-throughput biochemical assays. However, the transport direction is limited to downward by the effect of gravity. In this study, we observed the vertical contact-separation process of droplet arrays under an inhomogeneous magnetic field. Because the intensity of a magnetic field decays from its center to its edges, only the magnetic particles in droplets within a threshold distance from the center were transported upward. We estimated the resolution of the visualization according to the threshold distance. We then succeeded in improving the resolution of the visualization by arranging the droplet array in a partially spiral conformation. Our method could contribute to the high-throughput manipulation of magnetic materials, such as magnetically labeled cells.