A miniature MRI technique that enables imaging of internal structures of micrometer-sized samples with nanometer resolution has been developed. This technology is called magnetic resonance force microscopy (MRFM), which detects and images magnetic resonance phenomena as mechanical forces. To achieve high-resolution MRFM, it has been necessary to design smaller and sharper magnets because a larger magnetic field gradient is required. On the other hand, a smaller magnet also limits the magnetic field distribution to a narrower area, and scanning a wide area requires time in the order of half a day. In this study, an ultra-sensitive magnetic force sensor that is extremely soft and sensitive to even the weakest forces was developed using silicon microfabrication technology, and spherical micro magnetic particles were attached to develop an MRFM system for electron spin resonance (ESR) detection that has both high sensitivity and a wide range, which will lead to higher speed in the future. In the conversion process from the 3D force distribution to the 3D radical density distribution obtained from the measurement, a convolutional fast Fourier transform using random noise was used to realize a faster and more accurate 3D imaging.

Assessment of impaired insulin secretion and insulin resistance are critical to determining the type of diabetes and planning optimal management and preventive strategies in clinical practice. To measure insulin resistance, a minimally invasive needle with measurement and administration flow channels for local glucose tolerance tests was fabricated. The administration flow channel has a hole on the tip end of the flow channel. The microperfusion flow channel starts from the root side of the needle, turns around at the needle-tip end, and returns back to the root side of the needle. It has a perforated membrane on the surface of the area placed in the skin when inserted. Glucose is administrated through the flow channel, and glucose concentration of the skin is measured by microperfusion before and after administration. When the perfusate is perfused into the microperfusion flow channel, since the glucose concentration of the skin is higher than the perfusate, glucose contained in the skin's interstitial fluid moves into the flow channel through the perforated membrane by concentration diffusion, and the glucose can be collected. The needle's administration and glucose-collecting functions were evaluated in the skin of mice.

We developed a static magnetic field for miniaturization of the nuclear magnetic resonance (NMR) measurement system to measure nutrient solution in agricultural field. Instead of the large electromagnets used in our previous work, a permanent magnet was used to establish a static magnetic field. The design was based on the Halbach array, which allows the magnetic field to be concentrated on one side to increase the magnetic force. To avoid the problem of reducing the magnetic force of the magnets, the array magnets were optimized so that they could be composed of a combination of simple square prism magnets. Observation of the magnetic flux density of the fabricated permanent magnets showed that the magnetic flux density at the center was 0.946 T, and an error of less than 5 mT in magnetic flux density could be achieved. As a result, we succeeded in producing the permanent magnet.NMR measurements of water and air were performed using the produced magnets. When measuring water, a signal at 39.679 MHz was observed, which is the signal of hydrogen. In contrast, no signal was observed in air. Therefore, the NMR signal was successfully measured using the fabricated permanent magnet.