The RAFE that we developed enabled an expert endoscopist to perform the ESD procedure without any problems and allowed a non-endoscopist to control the endoscope more easily and quickly than a manual endoscope. The RAFE is expected to undergo further development.

We have developed a new matrix array transducer for controlling the behavior of microbubbles, which is different from that for high-intensity focused ultrasound (HIFU) therapy, in order to emit continuous wave by designing an acoustic field including multiple focal points. In the experiment using a thin-channel model, a wider acoustic field has an advantage for trapping microbubbles. In the experiment using a straight-path model, we have confirmed that a higher concentration of acoustic energy does not result in more aggregates. The dispersion of acoustic energy is important because the trapping performance is affected by the relationship between the shape of the acoustic field and the concentration of the suspension.

Early-stage gastrointestinal cancer is often treated by endoscopic submucosal dissection (ESD) using a flexible endoscope. Compared with conventional percutaneous surgery, ESD is much less invasive and provides a high quality of life for the patient because it does not require a skin incision, and the organ is preserved. However, the operator must be highly skilled because ESD requires using a flexible endoscope with energy devices, which have limited degrees of freedom. To facilitate easier manipulation of these flexible devices, we developed a surgical robot comprising a flexible endoscope and two articulating instruments. The robotic system is based on a conventional flexible endoscope, and an extrapolated motor unit moves the endoscope in all its degrees of freedom. The instruments are thin enough to allow insertion of two instruments into the endoscope channel, and each instrument has a bending section that allows for up–down, right–left, and forward–backward motion. In this study, we performed an ex vivo feasibility evaluation using the proposed robotic system for ESD in a porcine stomach. The procedure was successfully performed by five novice operators without complications. Our findings demonstrated the feasibility of the proposed robotic system and, furthermore, suggest that even operators with limited experience can use this system to perform ESD.

Bubble liposomes (BLs), which are gas-encapsulated liposomes several hundred nanometers in diameter, are expected to be developed as a novel tool for gene and drug delivery using ultrasound acoustic radiation force. However, since BLs are several hundred nanometers in diameter, difficulties exist in controlling their behaviors in blood flow under ultrasound exposure, since acoustic radiation forces have less effect on these small bubbles. In this study, we investigated the feasibility of active control of BLs in an artificial blood vessel under ultrasound exposure and attempted to evaluate the controllability. Then, we investigated the appropriate ultrasound conditions for active path selection of BLs in a bifurcated flow by applying acoustic radiation force. We prepared a single transducer to orient BLs toward one desired path. Two other transducers were targeted at the two paths after the bifurcation. We evaluated the areas of trapped BLs in the two paths after the bifurcation, to determine which path had increased BLs. The result showed a significant increase in area of trapped BLs in the desired path compared to the other path. Then, we defined the induction index of BLs by evaluating the area of trapped BLs, and changed the ultrasound conditions for active path selection of BLs by varying the sound pressure and frequency. We found that more BLs could be oriented to a desired path at higher sound pressure. For further study, we are aiming at active control of BLs in vivo.

Quantitative and qualitative evaluations of the fluorolaser navigation system show that it can support accurate guidance and intuitive surgical tool insertion procedures without preoperative 3D image volumes and registration processes.