Maintaining cellular integrity during storage is essential for the stable handling and quality control of living cells in future sensor-integrated biological systems. In this study, we investigated whether plant-derived substances improve the effectiveness of a supercooling-based nonfreezing preservation method for early embryos while maintaining cellular integrity. Mouse 2-cell embryos were used as a model system, and the University of Wisconsin (UW) solution was used as the basal preservation medium. Coffee lees extract was examined as a plant-derived preservation agent, and its representative components, caffeine and chlorogenic acid, were evaluated. Embryos preserved in UW solution alone at -6°C for 72 h showed residual membrane deformation, whereas supplementation with coffee lees extract, particularly at 10%, improved post-preservation morphology. Caffeine showed concentration-dependent protective and adverse effects, with the intermediate concentration providing the most favorable preservation outcome. Additional supporting experiments demonstrated that coffee lees extract and caffeine maintained stable supercooling without freezing under prolonged storage conditions and improved cytoskeletal integrity and post-preservation developmental competence, as assessed by blastocyst development after culture. These findings demonstrate that natural plant-derived substances enhance the nonfreezing preservation of early embryos under supercooling conditions while maintaining cellular integrity. The proposed method may provide a practical basis for the storage, transport, and quality control of living cells and support future applications involving sensor-integrated biological systems.
Because autonomous mobile robots require pose information for navigation, localization is crucial. Localization estimates a robot’s pose by matching currently observed features with a pre-constructed map. However, each sensor has environments in which the localization accuracy deteriorates owing to the environmental dependency of the sensors, making robust localization with a single sensor difficult. Sensor multiplexing methods have been proposed to address this issue. In addition, condition changes can alter observed environmental features, causing mismatches between current observations and the map because of the condition dependency of maps. This makes robust localization in such environments difficult. Map multiplexing methods have been proposed to address this. Robust localization can be achieved against the environmental dependency of sensors by multiplexing sensors and against the condition dependency of maps by multiplexing maps. However, multiplexing using sensors or maps is insufficient to achieve robust localization against both types of dependency. Hence, in this paper, we propose a system that multiplexes both sensors and maps. Experiments using a dataset confirmed that the proposed system achieved robust localization against both types of dependency.
“Sensor introduction into cells and tissues for information transmission” is crucial for understanding cellular and tissue states, as it allows real-time, noninvasive monitoring of dynamic physiological changes. In this review article, we highlight ultrasound technologies for cells and tissues as noninvasive, highly penetrative mechanical modalities for both sensor introduction and information retrieval. In both ultrasonic sensors and actuators, a persistent trade-off remains between achieving higher resolution through increased frequencies and the resultant significant signal attenuation. Ultimately, innovations in optical technologies play a significant role in advancing ultrasonic systems, and vice versa, fostering cross-disciplinary breakthroughs in biomedical engineering.
Cells possess sensors to detect external mechanical stimuli, and the process of converting these cues into biochemical reactions is known as mechanotransduction. Various vibration devices have been developed to evaluate cellular responses under vibratory stimulation. However, few devices can apply vibratory stimulation to a localized area while maintaining a low contamination risk during long-term culture. To address this challenge, we propose a magnetically driven device capable of applying vibratory stimulation to cells in vitro to evaluate cell proliferation and differentiation induction. The device integrates a polydimethylsiloxane membrane equipped with a neodymium magnet and a ring structure into a standard lidded culture dish. By utilizing the magnetic repulsive force from an electromagnet, the membrane vibrates via non-contact actuation. The device maintains a semi-sealed environment, minimizing the risk of contamination and making it highly suitable for long-term cultivation. Performance evaluations confirmed that membrane acceleration increased with the applied voltage. When vibratory stimulation with an acceleration of 0.1 G or higher was applied to cultured cells, the stimulated group exhibited a cell proliferation rate approximately 1.4 times greater than that of the non-stimulated group. Furthermore, culturing osteoblast-like cells in a differentiation-inducing medium resulted in widespread positive staining for alkaline phosphatase, confirming that the device environment supports osteogenic differentiation. Notably, no contamination or cell detachment occurred during a 72 h culture period. These results suggest that the proposed device is a potentially useful tool for evaluating cellular mechanotransduction under vibratory stimulation.
The turning motion of snake-like robots based on center of gravity shift has superior energy efficiency compared to the undulatory locomotion that simultaneously drives many joints, but precise guidance control has been difficult due to its nonlinear dynamic characteristics. In this paper, we propose a control method using deep reinforcement learning for following target points in all directions in the turning motion using center of gravity shift and ground reaction forces. The target direction is defined as a normalized vector in the body coordinate system. This allows us to present target direction information to the agent that is independent of changes in self-orientation, and we show that it can acquire a policy for accurate following in all directions. The results of motion analysis confirmed that the learned policy not only skillfully utilizes the ground reaction forces at the time of contact to make dynamic trajectory corrections, but also achieves target following by flexibly switching the turning strategy according to the target direction.
