Increased intrapelvic pressure (IPP) due to irrigation during flexible ureteroscopy (f-URS) can pose a risk of postoperative severe urinary tract infection associated with pyelovenous backflow. An automatic regulation system for maintaining safe IPP levels could enable surgeons to perform f-URS safely without postoperative complications. This study aimed to assess the measurement accuracy of an ultra-miniature fiber-optic pressure sensor incorporated into a small-caliper ureteroscope for assessing IPP and to develop an automatic irrigation system linked to this sensor. A porcine kidney was used for the ex vivo experiment. The nephrostomy catheter, connected to the conventional pressure transducer, was placed on the renal pelvis to evaluate the actual IPP (a-IPP). For measuring IPP using the fiber-optic pressure sensor (fo-IPP) built into the f-URS, a diaphragm pressure sensor of Φ250 μm was used. To establish an irrigation system, the optimal proportional–integral–derivative (PID) controller was explored to accurately adjust the irrigation pump flow rate. A high correlation between a-IPP and fo-IPP was confirmed across irrigation pressure values of 60–180 mbar (all, r ≥ 0.7, p < 0.001). When performing bolus irrigation, although fo-IPP showed relatively a higher peak value than a-IPP, the response time of fo-IPP was equivalent to that of a-IPP. After PID parameter optimization, our automatic irrigation system based on fo-IPP smoothly and accurately regulated the intended IPP set in the 5–20 mmHg range without overshooting. We successfully developed and demonstrated an automatic irrigation system regulating IPP based on the PID controller for f-URS, utilizing a fiber-optic pressure sensor. Further research, including in vivo studies, will be needed to assess clinical feasibility.

The ability to sense force in surgery is in high demand in many applications such as force feedback in surgical robots and remote palpation (e.g., tumor detection in endoscopic surgery). In addition, recording and analyzing surgical data is of substantial value in terms of evidence-based medicine. However, force sensing in surgery remains challenging because of the specific requirements of surgical instruments, namely, they must be small, bio-compatible, sterilizable, and tolerant to noise. In this study, we propose a modular optic force sensor using a Fabry–Perot interferometer that can be used on surgical devices. The the proposed sensor can be implemented like a strain gauge, which is widely used in industrial applications but not compatible with surgery. The proposed sensor includes two key elements, a fiber-optic pressure sensor using a Fabry–Perot interferometer that was previously developed by one of the authors and a structure that includes a carbide pin that contacts the pressure sensor along the long axis. These two elements are fixed in a guide channel fabricated in a 3 × 2 × 0.5 mm sensor housing. The experimental results are promising, revealing a linear relationship between the output and the applied load while showing a linear temperature characteristic that suggests temperature compensation will be needed in use.

Background and purpose: This study aimed to evaluate the characteristics of ureteral access sheaths (UASs) that can reduce the insertion force while accessing the upper urinary tract. Materials and methods: Six different types of 12/14-Fr UASs were used. We evaluated the properties of UASs such as the diameter of the outer sheath, length of the inner dilator tip exposed from the outer sheath, sheath flexibility (assessed in terms of bending force of the tip or base), flexibility ratio (i.e., bending force value of tip-to-base ratio), and frictional force of the outer sheath surface. We measured the force required for inserting the UAS into an artificial ureteral model and examined the correlation between the relevant characteristics and insertion force for each UAS. Results: Overall, a lower tip-to-base flexibility ratio (r = 0.66) and a lower frictional force (r = 0.50) were inversely correlated with insertion force. The force of insertion into the bifurcation was associated with the flexibility of the base (r = -0.64), flexibility ratio (r = 0.79), and frictional force (r = 0.66). Moreover, a shorter dilator tip (r = 0.52), lower flexibility ratio (r = 0.52), and lower frictional force (r = 0.50) were correlated with a lower insertion force at the proximal ureter. Conclusion: A UAS with a rigid base and flexible tip parts, a smoother surface, and a shorter dilator tip would be preferable for reducing the insertion force. These findings may be crucial for selecting or developing an ideal UAS that can decrease the risk of ureteral injury.

This study examines restroom cleanliness in public facilities, department stores, supermarkets, and schools by using water droplet volumes around washbowls as an indicator of usage. Rising cleaning costs due to labour shortages necessitate more efficient restroom maintenance. Quantifying water droplet accumulation and predicting cleaning schedules can help optimise cleaning frequency. To achieve this, water droplet volumes were measured at specific time intervals, with significant variations indicating increased restroom usage and potential dirt buildup. For real-world assessment, acrylic plates were placed on both sides of washbowls in public restrooms. These plates were collected every hour over five days and analysed using near-infrared photography to track changes in water droplet areas. The collected data informed the development of a prediction system based on the decision tree method, implemented via the LightGBM framework. This paper presents the developed prediction system, which utilises in situ water droplet volume measurements, and evaluates its accuracy in forecasting restroom cleaning needs.

Plasma actuators are promising devices for near-wall flow control; however, conventional actuators often produce jets and forcing regions with excessive wall-normal spread, which reduces near-wall actuation selectivity. In this study, micro plasma actuator arrays with SDBD and pulsed-DC configurations were experimentally characterized to examine jets and forcing patterns confined closer to the wall. Micro actuator arrays consisting of eight integrated elements with sub-millimeter electrodes (0.5 mm exposed width) were fabricated by photolithography. Mean velocity fields were evaluated by conventional particle image velocimetry (PIV), while near-electrode flow structures were examined by single-pixel PIV. In addition, the streamwise body-force distribution was estimated from the high-spatial-resolution velocity fields. The results showed that the micro actuator arrays formed jets confined closer to the wall than the conventional actuators, with repeated re-acceleration along the electrode array. The estimated body-force distribution showed that the SDBD configuration retained a reverse-sign forcing pattern near the wall, whereas the pulsed-DC configuration formed a more concentrated near-wall positive forcing pattern with a weaker reverse-sign region and a lower positive peak location (0.54 mm, compared with 1.38 mm for the SDBD configuration). Under the tested quiescent-air characterization conditions, the pulsed-DC configuration produced a more wall-confined positive estimated-forcing pattern.