A combinatorial biofilm treatment involving a low dose of antibiotics along with a small amount of electricity is known as the bioelectric effect (BE). When an external electric field or current is applied, biofilms can be affected by the resulting electrostatic force. Our group is researching the maximization of electrostatic force through the integration of both alternating and direct currents, with a voltage below the electrolysis threshold (0.82 V). To validate the efficacy of this technology, in the present work we investigated two major biofilm applications: (1) dentistry for oral biofilm infection and (2) hygiene for aerobic biofilm contamination. For each application, testing devices were developed in the form of a toothbrush and an evaporator cleaner, respectively. The dental clinical results demonstrated a 75% reduction in gingivitis compared to the non-BE applied group (n = 40, ANOVA, paired t-test, p < 0.05). Meanwhile, the hygiene testing result demonstrated an 81.8% increase in biofilm removal compared to the initial untreated sample (n = 6, ANOVA, paired t-test, p < 0.05). In conclusion, this new BE technology showed efficacy in both dental- and hygiene-associated biofilms without causing electrolysis. Further investigation and development of the BE system should continue in both the medical and hygiene fields.

By virtue of their upright locomotion, similar to that of humans, motion analysis of non-human primates has been widely used in order to better understand musculoskeletal biomechanics and neuroscience problems. Given the difficulty of conducting a marker-based infrared optical tracking system for the behavior analysis of primates, a 2-dimensional (D) video analysis has been applied. Distinct from a conventional marker-based optical tracking system, a depth image sensor system provides 3-D information on movement without any skin markers. The specific aim of this study was to develop a novel algorithm to analyze the behavioral patterns of non-human primates in a home cage using a depth image sensor. The behavioral patterns of nine monkeys in their home cage, including sitting, standing, and pacing, were captured using a depth image sensor. Thereafter, these were analyzed by observers’ manual assessment and the newly written automated program. We confirmed that the measurement results from the observers’ manual assessments and the automated program with depth image analysis were statistically identical.

A compromised stability in the elderly population is considered a major factor for fall risk assessment. The dynamic stability of human gait with various mathematical metrics has been extensively studied to find a prediction index and fall prevention strategies that can be embedded in a wearable monitoring sensor. In this study, the zero-moment point method (ZMP) was utilized for analyzing the gait stability of young and elderly female populations. Participants in the young and elderly female groups with no musculoskeletal disorders and fall experience were asked to walk at a habitual speed on 10 m flat ground. Dynamic instability is defined by the percentage of the ZMP values that fall outside the base of support during one gait cycle. The ZMP trajectory between the left and right leg swing was not symmetrical considering flat-ground walking. Also, there was no statistical difference in the dynamic stability in the anterior–posterior direction (71.3 ± 7.9% for the young group and 73.6 ± 7.6% for the elderly group), but walking in the medial–lateral direction was more stable in the elderly group (53.9 ± 8.6%) than in the young group (44.1 ± 11.2%) because the habitual walking speed decreased in the elderly group.

An accurate thermal measurement of low-frequency stimulation (LFS) pads for thermotherapy was investigated using background subtraction (BGS) methods. The safety of LFS thermal pads must be investigated to prevent low-temperature burns (LTBs), because they frequently contact the sensitive skin in neck, shoulder and abdominal regions. The thermal measurement was based on thermal imaging using the active region-of-interest (ROI) from a foreground. The shape of the LFS thermal pad consists of complicated curves, thus it is difficult to extract the foreground using conventional shapes of ROIs. We proposed the foreground extraction using background subtraction (BGS) and digital and morphological filters to time-variant thermal images. The foreground extraction was implemented using open sources and experimented for abdominal, cervical and patellar pads. The results showed that the foreground can be separated from background regardless of the size, position, orientation and shape of the pad. The thermal characteristics of the LFS thermal pads were evaluated from the complicated shapes of the foreground with high accuracy. This study demonstrated that standard deviation of pixel history (SDPH) is a simple method for the BGS, but the SDPH is useful to find the safety risk of LTBs and prevent them in advance. The results also showed that the proposed SDPH was simple but had remarkable accuracy compared with the conventional BGS methods. These BGS methods are expected to increase the reliability of products used on the human body. Further, the BGS methods can be used to inspect the temperatures of static products in industrial processes.

Biofilms comprise diverse bacteria and fungi with slime material, especially in humid conditions. The surface of the heat ventilation and air conditioning (HVAC) system, especially at the evaporator, is in high moisture conditions due to the compression and relaxation of refrigerant. Biofilms comprise electrically polarized molecules, which include polysaccharide, DNA, liposome, and diverse amino acids. Thus, when an electric field is applied to biofilms, the field creates an electrostatic force that enhances the destruction of biofilms and results in detachment from the surface. The principles are known as the bioelectric effect. A new bioelectric (BE) technology has been developed that is focused on the optimization of electrical energy for biofilm removal, and its efficacy has been previously demonstrated. In this work, a prototype of the BE device for HVAC application has been fabricated and tested. Escherichia coli (E. coli) biofilms were utilized as a standard model of biofilm on the HVAC evaporator. The results demonstrate that when the BE technology was applied for one hour, approximately 81.8% of total biofilm was removed. Furthermore, live cells in biofilms were reduced by approximately 71.4% under the BE device, compared to non-treated biofilms.