Search

Relaxation is a critical counterbalance to the demands of modern business life. Footbaths, a simple yet highly effective therapeutic practice, have been used for centuries across various cultures to promote relaxation and overall well-being. This study presents a novel approach to simulating the experience of a public footbath through the use of tactile and thermal stimulation of airflow to the calf and those on the foot soles. Our system aims to offer a realistic and immersive virtual footbath experience without the need for actual water, by controlling the temperature and airflow to mimic the sensation of soaking feet in water or a water wave. Without using actual water, our system can be more compact, highly responsive, and more reproducible. The layer of airflow is made as thin as possible by adjusting air outlet, and the Coanda effect is also considered to generate a water surface more realistic. The system can provide a multi-sensory experience, including visual and audio feedback of water flow, enhancing the relaxation and therapeutic benefits of a footbath., Comment: Part of proceedings of 6th International Conference AsiaHaptics 2024

In this study, we experimentally demonstrated that the nonlinear optical coefficient of the original Si can be enhanced by incorporating a metamaterial structure into an existing silicon waveguide. The two-photon absorption coefficient enhanced by the metamaterial structure was 424 cm/GW, which is 1.2x10^3 times higher than that of Si. Using this metamaterial waveguide-based nonlinear optical activation function, we achieved a high inference accuracy of 98.36% in the handwritten character recognition task, comparable to that obtained with the ReLU function as the activation function. Therefore, our approach can contribute to the realization of more power-efficient and compact all-optical neural networks., Comment: 4 pages, 5 figures

We investigate interference between topological interfacial modes in a semiconductor photonic crystal platform with Dirac frequency dispersions, which can be exploited for interferometry switch. It is showcased that, in a two-in/two-out structure with four topological waveguides, geometric phases of the two-component spinor wavefunctions of topological photonic modes accumulate at turning points of waveguides, which govern the interferences and split the electromagnetic energy into two output ports with relative power ratio tunable by the relative phase of inputs. We unveil that this brand-new photonic phenomenon is intimately related to the spin-momentum locking property of quantum spin Hall effect, and results from the symphonic contributions of three phase variables: the spinor phase and geometric phase upon design, and the global phase controlled from outside. The present findings open the door for manipulating topological interfacial modes, thus exposing a new facet of topological physics. The topology-driven interference can be incorporated into other devices which is expected to leave far-reaching impacts to advanced photonics, optomechanics and phononics applications., Comment: 25 pages, 4 figures

Numerous studies have been conducted on display techniques for intranasal chemosensory perception. However, a limited number of studies have focused on the presentation of sensory spatial information. To artificially produce intranasal chemosensory spatial perception, we focused on a technique to induce intranasal chemosensation by transcutaneous electrical stimulation between the nasal bridge and the back of the neck. Whether this technique stimulates the trigeminal nerve or the olfactory nerve remains debatable; if this method stimulates the trigeminal nerve, the differences in the amount of stimulation to the left and right trigeminal branches would evoke lateralization of intranasal chemosensory perception. Therefore, we propose a novel method to lateralize intranasal chemosensation by selectively stimulating the left or right trigeminal nerve branches through the shifting of an electrode on the nasal bridge to the left or right. Finite element simulations reveal that electrical stimulation applied between the electrodes on the left/right nasal bridge and the back of the neck results in the construction of a high current density area on the left/right branch of the trigeminal nerve. The results of two psychophysical experiments reveal that intranasal chemosensation can be lateralized by using the proposed method. The results of our experiment also suggest that lateralization is not the result of electrically induced tactile sensation of the skin surface but rather due to the distribution of stimuli to the trigeminal nerves. To the best of our knowledge, this study is the first successful lateralization of intranasal chemosensation that utilizes an easy-to-apply method without involving nostril blocking.

Optical waveguide theory is essential to the development of various optical devices. Although there are reports on the theory of optical waveguides with magneto-optical (MO) and magnetoelectric (ME) effects, a comprehensive theoretical analysis of waveguides considering these two effects has not yet been published. In this study, the conventional waveguide theory is extended by considering constitutive relations that account for both MO and ME effects. Using the extended waveguide theory, the propagation properties are also analyzed in a medium where metamaterials and magnetic materials are arranged such that MO and ME effects can be controlled independently. It has been confirmed that the interaction between MO and ME effects occurs depending on the arrangement of certain metamaterials and the direction of magnetization. This suggests a nonreciprocal polarization control that rotates the polarization in only one direction when propagating in free space and enhances the nonreciprocal nature of the propagating waves in waveguide propagation., Comment: 24 pages, 9 figures

Pseudo-haptic techniques are used to modify haptic perception by appropriately changing visual feedback to body movements. Based on the knowledge that tendon vibration can affect our somatosensory perception, this paper proposes a method for leveraging tendon vibration to enhance pseudo-haptics during free arm motion. Three experiments were performed to examine the impact of tendon vibration on the range and resolution of pseudo-haptics. The first experiment investigated the effect of tendon vibration on the detection threshold of the discrepancy between visual and physical motion. The results indicated that vibrations applied to the inner tendons of the wrist and elbow increased the threshold, suggesting that tendon vibration can augment the applicable visual motion gain by approximately 13\% without users detecting the visual/physical discrepancy. Furthermore, the results demonstrate that tendon vibration acts as noise on haptic motion cues. The second experiment assessed the impact of tendon vibration on the resolution of pseudo-haptics by determining the just noticeable difference in pseudo-weight perception. The results suggested that the tendon vibration does not largely compromise the resolution of pseudo-haptics. The third experiment evaluated the equivalence between the weight perception triggered by tendon vibration and that by visual motion gain, that is, the point of subjective equality. The results revealed that vibration amplifies the weight perception and its effect was equivalent to that obtained using a gain of 0.64 without vibration, implying that the tendon vibration also functions as an additional haptic cue. Our results provide design guidelines and future work for enhancing pseudo-haptics with tendon vibration., Comment: This paper has been accepted by IEEE TVCG

We present a comment on "Spin-Momentum-Locked Edge Mode for Topological Vortex Lasing, Phys. Rev. Lett. vol. 125, 013903 (2020)"(hereafter the Letter).In the Letter, Yang et al. reported on an elegant topological vortex laser and proposed that the near-field spin and OAM of the topological edge mode lasing have a one-to-one far-field radiation correspondence. The near-field information is based on frequency dispersions of the topological edge modes, without supporting measurements and/or computer simulations. Unfortunately, their frequency dispersions shown in Fig. 1(c) (see also Fig. S6 and Eqs. (5.3) and (5.4) in Supplemental Material) are wrong. As the result, the mode assignment of the main mode |-2,+> investigated in the Letter is mistaken, which should be |2,+>. This spoils the one-to-one correspondence claimed in the Letter.

2D materials are expected to be favorable channel materials for field-effect transistor (FET) with extremely short channel length because of their superior immunity to short-channel effects (SCE). Graphene, which is the most famous 2D material, has no bandgap without additional techniques and this property is major hindrance in reducing the drain leakage. Therefore, 2D materials with finite band gap, such as transition metal dichalcogenides (TMDs, e.g. MoS2 WSe2) or phosphorene, are required for the low power consumption FETs. Hafnium disulfide (HfS2) is a novel TMD, which has not been investigated as channel material. We focused on its potential for well-balanced mobility and bandgap properties. The higher electron affinity of Hf dichalcogenides compared with Mo or W chalcogenides facilitates the formation of low resistance contact and staggered heterojunction with other 2D materials. Here we demonstrate the first few layer HfS2 FET with robust current saturation and high current on/off ratio of more than 10^4., Comment: 16 pages, 10 figures

Is it possible to actually make Harry's invisibility cloaks? The most promising approach for realizing such magical cloaking in our real world would be to use transformation optics, where an empty space with a distorted geometry is imitated with a non-distorted space but filled with transformation medium having appropriate permittivity and permeability. An important requirement for true invisibility cloaks is nonreciprocity; that is, a person in the cloak should not be seen from the outside but should be able to see the outside. This invisibility cloak, or a nonreciprocal shield, cannot be created as far as we stay in conventional transformation optics. Conventional transformation optics is based on Riemann geometry with a metric tensor independent of direction, and therefore cannot be used to design the nonreciprocal shield. To overcome this problem, we propose an improved theory of transformation optics that is based on Finsler geometry, an extended version of Riemann geometry. Our theory shows that nonreciprocal shielding can be realized by covering cloaking space with transformation medium having anisotropic, nonreciprocal permittivity and permeability. This theory includes conventional transformation optics as special cases. We show the method for designing the spatial distribution of the permittivity and permeability required to make the nonreciprocal shield., Comment: 10 pages, 2 figures