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OBJECTIVE: To enhance satisfaction, the cosmetics industry needs to clearly understand consumers' descriptions of their key tactile preferences. It is difficult for researchers to understand verbal descriptions from people whose native language is different from their own. Previous research has implied that some sensory words with the same lexical meanings have been observed in different haptic exploratory procedures (HEPs). Therefore, our study aims to investigate and understand the key tactile perceptions of people from five different countries based on their descriptions and their HEPs. METHODS: In Experiment 1, 1545 participants living in the US, Japan, China, Italy, and Thailand described their major tactile perceptions as efficacy in skincare, and we analysed the frequency of each word used in their answers. In Experiment 2, we confirmed the task to observe HEPs for Chinese, Italian, and Thai participants. A total of 24 participants in China, 33 participants in Italy, and 30 participants in Thailand freely explored their faces with their hands and answered which side more closely matched the major tactile adjectives. Experts classified the observed HEPs into six classifications within two categories and three contact area sizes and investigated the cultural differences. RESULTS: More than 2% of the Chinese, Italian, Thai, US, and Japanese participants described 33, 20, 29, 22, and 18 words, respectively, as efficacy in skincare. Verified words that described the major tactile perceptions in each native language had the same meanings as moistness, firmness, softness, smoothness, and so on. We could confirm the HEPs of these major feelings for the participants from each culture. Chinese and Thai participants' HEPs for moistness or softness were observed with a pressing movement. Conversely, Italian participants' HEPs for moistness or softness were observed with a rubbing movement. CONCLUSION: This study showed that words with the same lexical meanings evoked different HEPs. The results imply that different HEPs can provide different physical stimuli on the skin. Therefore, it is important to survey both objects and HEPs to better understand the tactile experience.

OBJECTIF: Pour améliorer la satisfaction, l'industrie cosmétique doit bien comprendre les descriptions que font les consommateurs de leurs principales préférences tactiles. Il est difficile pour les chercheurs de comprendre les descriptions verbales des personnes dont la langue maternelle est différente de la leur. Des recherches antérieures ont suggéré que certains mots sensoriels ayant les mêmes significations lexicales ont été observés dans différentes procédures exploratoires haptiques (PEH). Par conséquent, notre étude vise à étudier et à comprendre les perceptions tactiles clés des personnes de cinq pays différents en fonction de leurs descriptions et de leurs PEH. MÉTHODES: Dans l'expérience 1 545 participantes vivant aux États­Unis, au Japon, en Chine, en Italie et en Thaïlande ont décrit leurs principales perceptions tactiles comme l'efficacité dans les soins de la peau, et nous avons analysé la fréquence de chaque mot utilisé dans leurs réponses. Dans l'expérience 2, nous l'avons confirmé en observant les PEH pour les participantes chinoises, italiennes et thaïs. 24 participantes en Chine, 33 participantes en Italie et 30 participantes en Thaïlande ont librement exploré leur visage avec leurs mains et ont répondu à la question de savoir quel côté correspondait le mieux aux principaux adjectifs tactiles. Les experts ont classé les PEH observées en six classifications dans deux catégories et trois tailles de surface de contact, et ont étudié les différences culturelles. RÉSULTAT: Plus de deux pour cent des participantes chinoises, italiennes, thaïs, américaines et japonaises ont décrit 33, 20, 29, 22 et 18 mots, respectivement, comme une efficacité dans les soins de la peau. Les mots vérifiés qui décrivaient les principales perceptions tactiles dans chaque langue maternelle ayant les mêmes significations sont l'humidité, la fermeté, la douceur, la texture lisse, etc. Nous avons pu confirmer les PEH de ces sensations majeures pour les participants de chaque culture. Les PEH des participantes chinoises et thaïs pour l'humidité ou la douceur ont été observées avec un mouvement de pression. A l'inverse, les PEH pour l'humidité ou la douceur des participantes italiennes ont été observées avec un mouvement de frottement. CONCLUSION: Cette étude a montré que les mots ayant les mêmes significations lexicales évoquaient différentes PEH. Les résultats impliquent que différentes PEH peuvent fournir différents stimuli physiques sur la peau. Par conséquent, il est important d'étudier les objets et les PEH pour mieux comprendre l'expérience tactile.

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BACKGROUND: Tactile sensation plays a crucial role in object manipulation, communication, and even emotional well-being. It has been reported that the deformability of skin (also described as skin compliance) that shows a large mechanical response to stimuli is associated with high tactile sensitivity. However, although the compliance of the stratum corneum, the outermost layer of skin, can change daily due to skin care and environmental factors, few studies have quantified the effect of the stratum corneum on tactile sensation. AIMS: We investigated the changes in tactile sensitivity resulting from skin hydration and identified corresponding alterations in the compliance of the stratum corneum. METHODS: A randomized controlled trial was conducted. Participants were randomly assigned to an intervention group (n = 20) that had a moisturizing cream applied to their cheeks or a control group (n = 19) that had Milli-Q water applied to their cheeks. Tactile discrimination performance was assessed using psychophysical techniques before and after application. The water content, mechanical response characteristics, and penetration of PEG/PPG-17/4 dimethyl ether from the cream in the stratum corneum were evaluated to identify hydration effects. Skin deformations occurring during tactile sensation were measured concurrently using a suction device employed for tactile stimulation. RESULTS: Tactile sensitivity was increased in participants who had cream applied to the skin surface, while no significant change was observed in participants who received Milli-Q water. The improved discrimination of tactile stimulus intensity was directly related to the magnitude of skin displacement. The higher water content of the stratum corneum due to cream application decreased the dynamic modulus of elasticity of the stratum corneum and increased the skin's extensibility in response to tactile stimuli. CONCLUSIONS: Hydrating the stratum corneum significantly enhances tactile sensitivity and is accompanied by an increase in skin extensibility, a factor in tactile intensity perception. The compliance of the thin stratum corneum layer plays a crucial role in tactile experiences that involve skin stretching.

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OBJECTIVE: The mechanical condition and tactile evaluation of skin are essential for the development of skin care products. Most of the existing commercial instruments and studies aim to evaluate the skin surface by pressing it for hardness or by using imaging sensors, but there have been few instrumental measurements employing rubbing motion. Here, we have developed a sensor specialized for tactile sensation and the contact phenomenon during skin rubbing. METHODS: The developed sensor has three features: It can measure body parts including cheeks and arms, automate the rubbing motion of the probe and measure vibration and friction simultaneously. It is hand-held, with metal probes that rub the skin surface while rotating under a motor drive; it has an accelerometer and a force sensor beneath the probe measuring vibration and friction forces. To evaluate the validity of the sensor's measurements, artificial skin models were measured using the developed sensor and commercially available sensors and the results were compared. The relationship between the sensor output, surface roughness measurement and sensory evaluation was also investigated. Additionally, we evaluated the inter-rater reliability when measuring actual skin. RESULTS: The measurements of five artificial skin models with different surface shapes showed a high correlation (r = 0.99) between the vibration intensity values evaluated by the developed sensor and those measured by a tri-axial acceleration sensor attached to a fingernail. The correlation coefficient between the vibration intensity values and surface roughness was r = 0.91, and the correlation with the sensory evaluation score of roughness was r = 0.99. The friction coefficients measured by the developed sensor and the force plate had r = 0.93, based on measurements of five artificial skin models with different friction conditions. The inter-rater correlation coefficients between the three participants of the developed sensor were as high as 0.92 and 0.94 for the vibration and friction measurements respectively. CONCLUSION: The vibration intensities and friction coefficients from the sensor were highly correlated with those of the conventional sensor. The inter-rater reliability was also high. The developed sensor can be useful for tactile evaluation in skin-care product development.

OBJECTIF: l'état mécanique et l'évaluation tactile de la peau sont essentiels au développement de produits de soins de la peau. La plupart des instruments disponibles sur le marché et des études publiées à ce jour évaluent la surface de la peau en la comprimant pour déterminer sa dureté ou en utilisant des capteurs d'imagerie, mais il n'y a eu que peu de mesures instrumentales utilisant le mouvement de frottement. Ici, nous avons développé un capteur spécialisé pour la sensation tactile et le phénomène de contact lors du frottement de la peau. MÉTHODES: le capteur développé possède trois caractéristiques : il permet d'exercer des mesures sur plusieurs parties du corps, y compris les joues et les bras ; il automatise le mouvement de frottement de la sonde et il mesure simultanément les vibrations et les frottements. Tenu à la main, doté de sondes en métal qui frottent la surface de la peau tout en tournant sous l'action d'un moteur, il est équipé d'un accéléromètre et d'un capteur de force situé sous la sonde qui mesure les forces de vibration et de frottement. Pour déterminer la validité des mesures du capteur, des modèles de peau artificielles ont été évalués à l'aide du capteur développé et de capteurs déjà disponibles sur le marché, et les résultats ont été comparés. Le lien entre les mesures réalisées à l'aide du capteur, la mesure de la rugosité de la surface de la peau et l'évaluation sensorielle a également été étudié. En outre, nous avons évalué la fiabilité inter-évaluateurs lors de la mesure réelle de la peau. RÉSULTATS: les mesures de cinq modèles de peau artificielle avec des formes de surface différentes ont montré une forte corrélation (r = 0,99) entre les valeurs d'intensité des vibrations évaluées par le capteur développé et celles mesurées par un capteur d'accélération triaxial fixé à un ongle. Le coefficient de corrélation entre les valeurs d'intensité des vibrations et la rugosité de la surface était r = 0,91, et la corrélation avec le score d'évaluation sensorielle de la rugosité était r = 0,99. Les coefficients de frottement mesurés par le capteur développé et la plaque de force étaient r = 0,93, sur la base des mesures de cinq modèles de peau artificielle avec des conditions de frottement différentes. Les coefficients de corrélation inter-évaluateurs entre les trois participants utilisant le capteur développé ont atteint 0,92 et 0,94 pour les mesures de vibrations et de frottement, respectivement. CONCLUSION: les intensités des vibrations et les coefficients de frottement du capteur se sont avérés fortement corrélés avec ceux du capteur conventionnel. La fiabilité inter-évaluateurs était également élevée. Le capteur développé peut être utile pour l'évaluation tactile lors du développement de produits de soins de la peau.

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BACKGROUND: The tactile perceptions arising on the skin mediate representations of the body and perceptions of the external physical world. Thus, these tactile sensations greatly impact our lives. Although tactile perception is caused by skin deformation, few studies have investigated the contribution of skin physical properties to tactile perception because the skin deformation in response to mechanical stimuli is difficult to measure in real time. In this study, we investigated how the skin deforms in response to externally applied mechanical stimuli and the effect of skin deformation on tactile perception. MATERIALS AND METHODS: Tactile perception was assessed using psychophysical methods. A suction device was used to measure skin deformation in response to mechanical stimuli while assessing tactile perception. The relationship between skin deformation and tactile perception was investigated. RESULTS: Individuals show different skin deformation behavior in response to stimuli of the same intensity, and the amount of skin deformation affects the perceived pressure induced by suction stimulation. Furthermore, when the amount of skin deformation is small, tactile perception becomes more difficult, and the ease of tactile perception varies. CONCLUSION: We argue that dynamic skin behavior is an important factor in tactile perception. Focusing on skin physical characteristics from a constructivist perspective of complex tactile perception may lead to improved tactile communication perception through the control of skin physical properties and realistic tactile presentation in remote environments.

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OBJECTIVE: Many people want to have healthy facial skin. They tend to check their skin's condition by touching their face with their hands. In the cosmetic industry, we need to understand what consumers are perceiving in a tactile sense when touching their own facial skin. The purpose of this study was to investigate these observation methods in order to systematically understand people's haptic exploratory procedures (HEPs). METHODS: Thirty-four participants living in the United States and twenty-two participants living in Japan freely explored their faces and answered which side felt more closely related to the six tactile adjectives. A new analysis was applied to classify the observed HEPs into six classifications within two categories and three sizes of contact area by experts. RESULT: It was confirmed that the new task was useful to observe the HEPs for participants from United States and Japan. The US participants' HEPs for 'moisturized' were mainly a middle-sized contact area using a stroking motion. On the other hand, Japanese participants' HEPs for 'moisturized' ('shittori' in Japanese) mainly used a pushing movement. Moreover, the US participants' HEPs for 'soft' included both pushing and stroking, but Japanese participants HEPs for 'soft' ('yawarakai' in Japanese) were again mainly pushing. CONCLUSION: This study suggests that the proposed analysis method enables the systematic understanding of HEPs when checking the skin, along with the cross-cultural differences affecting those procedures. These systematic findings could allow cosmetic formulators to have a better understanding of the tactile sensations consumers themselves are feeling in a variety of different global markets.

OBJECTIF: de nombreuses personnes veulent avoir une peau du visage en bonne santé. Elles ont tendance à examiner l'état de leur peau en se touchant le visage avec les mains. Dans l'industrie cosmétique, nous devons comprendre ce que les consommateurs perçoivent d'un point de vue tactile lorsqu'ils se touchent la peau du visage. L'objectif de cette étude était d'évaluer ces méthodes d'observation afin de comprendre de manière systématique les procédures exploratoires haptiques (PEH) des individus. MÉTHODES: trente-quatre participants vivant aux États-Unis et vingt-deux vivant au Japon ont librement examiné leur visage en le touchant et indiqué quel côté semblait le plus proche des six adjectifs tactiles. Une nouvelle analyse a été appliquée pour classer les PEH observées en six groupes de classification au sein de deux catégories et trois tailles de zone de contact par des experts. RÉSULTAT: il a été confirmé que cette nouvelle étude était utile pour observer les PEH chez les participants provenant des États-Unis et du Japon. Les PEH des participants américains pour l'adjectif « hydratée ¼ correspondaient principalement à des mouvements de caresse sur une zone de contact de taille moyenne. En revanche, les PEH des participants japonais pour « hydratée ¼ (« shittori ¼ en japonais) correspondaient principalement à des mouvements de pression. De plus, les PEH des participants américains pour l'adjectif « douce ¼ comprenaient à la fois des mouvements de caresse et de pression, mais celles des participants japonais pour « douce ¼ (« yawarakai ¼ en japonais) correspondaient de nouveau principalement à des mouvements de pression. CONCLUSION: cette étude suggère que la méthode d'analyse proposée permet une compréhension systématique des PEH lors de l'examen de la peau, ainsi que des différences interculturelles influençant ces procédures. Ces résultats systématiques pourraient permettre aux formulateurs de cosmétiques de mieux comprendre les sensations tactiles des consommateurs eux-mêmes pour un ensemble de marchés mondiaux différents.

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The quantification of stickiness experienced upon touching a sticky or adhesive substance has attracted intense research attention, particularly for application to haptics, virtual reality, and human-computer interactions. Here, we develop and evaluate a device that quantifies the feeling of stickiness experienced upon touching an adhesive substance. Keeping in mind that a typical pressure distribution sensor can only measure a pressing force, but not a tensile force, in our setup, we apply an offset pressure to a pressure distribution sensor and measure the tensile force generated by an adhesive substance as the difference from the offset pressure. We propose a method of using a magnetic force to generate the offset pressure and develop a measuring device using a magnet that attracts magnetic pin arrays and pin magnets; the feasibility of the method is verified with a first prototype. We develop a second prototype that overcomes the noise problems of the first, arising from the misalignment of the pins owing to the bending of the magnetic force lines at the sensor edges. We also obtain measurement results for actual samples and standard viscosity liquids. Our findings indicate the feasibility of our setup as a suitable device for measuring stickiness.

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BACKGROUND/AIMS: Few attempts have been made to distinguish the softness of different skin layers, though specific measurement of the superficial layer would be useful for evaluating the emollient effect of cosmetics and for diagnosis of skin diseases. MATERIALS AND METHODS: We developed a sensor probe consisting of a piezoelectric tactile sensor and a load cell. To evaluate it, we firstly measured silicone rubber samples with different softness. Then, it was applied to human forearm skin before and after tape-stripping. A VapoMeter and skin-surface hygrometer were used to confirm removal of the stratum corneum. A Cutometer was used to obtain conventional softness data for comparison. RESULTS AND CONCLUSIONS: Both the piezoelectric tactile sensor and the load cell could measure the softness of silicone rubber samples, but the piezoelectric tactile sensor was more sensitive than the load cell when the reaction force of the measured sample was under 100 mN in response to a 2-mm indentation. For human skin in vivo, transepidermal water loss and skin conductance were significantly changed after tape-stripping, confirming removal of the stratum corneum. The piezoelectric tactile sensor detected a significant change after tape-stripping, whereas the load cell did not. Thus, the piezoelectric tactile sensor can detect changes of mechanical properties at the skin surface. The load cell data were in agreement with Cutometer measurements, which showed no change in representative skin elasticity parameters after tape-stripping. These results indicate that our sensor can simultaneously measure the mechanical properties of the superficial skin layer and whole skin.

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Subcellular organelles in living cells were inactivated by tightly focusing femtosecond laser pulses inside the cells. Photodisruption of a mitochondrion in living cells was experimentally confirmed by stacking three-dimensional confocal images and by restaining of organelles. The viability of the cells after femtosecond laser irradiation was ascertained by impermeability of propidium iodide as well as by the presence of cytoplasmic streaming.