arXiv subjects

Eiji Iwase

Publications and source records attributed to Eiji Iwase.

6 recordsLinked to original sources

arXiv2026

3D-Printing Water-Soluble Channels Filled with Liquid Metal for Recyclable and Cuttable Wireless Power Sheet

A recyclable and cuttable wireless power transfer (WPT) sheet is proposed, enabled by H-tree wiring and water-soluble channels filled with liquid metal (LM). Conventional 2D WPT systems lose their functionality when physically damaged or modified. The H-tree wiring pattern maintains the operation of the remaining coils even after the outer region of the sheet is cut away. The LM can be recovered by dissolving 3D-printed polyvinyl alcohol (PVA) channels in water. The sheet dimensions were experimentally optimized, and a Q-factor over 55 was achieved at 6.78 MHz. The sheet maintained its bending stiffness and electrical resistance during 100 bending cycles. After four dissolution-refabrication cycles, 98 percent of the LM was recovered with stable electrical properties. The WPT sheet can be integrated into everyday objects and enables long-term, continuous operation of surrounding electronic devices, contributing to IoT applications and ambient computing.

cs.HC↗

arXiv2024

Friction jointing of distributed rigid capacitors to stretchable liquid metal coil for full-body wireless charging clothing

For full-body wireless power transfer (WPT), a liquid metal (LM)-based meandered textile coil has been proposed. Multiple rigid capacitors must be inserted in a long coil for efficiency; however, the conventional adhesive jointing suffers from the fragile connection between a rubber tube filled with LM and the capacitor due to the poor adhesion of the rubbers. This paper presents a friction-based jointing, which covers the capacitor with a rigid capsule to enhance the frictional force between the tube and capsule. By experimentally optimizing the capsule design, the LM coil with capacitors showed 3.1 times higher stretch tolerance (31.8 N) and 3.5 times higher bending tolerance (25.9 N) than the adhesive jointing. Moreover, the WPT garment prototype shows excellent mechanical durability against repeated stretching and washing over 100 times. Our full-body meandered textile coil can enable wireless charging to wearable devices around the body for long-term continuous healthcare monitoring, activity recognition, and AR/VR.

cs.HC↗

arXiv2018

Electro-mechano-optical detection of nuclear magnetic resonance

Signal reception of nuclear magnetic resonance (NMR) usually relies on electrical amplification of the electromotive force caused by nuclear induction. Here, we report up-conversion of a radio-frequency NMR signal to an optical regime using a high-stress silicon nitride membrane that interfaces the electrical detection circuit and an optical cavity through the electro-mechanical and the opto-mechanical couplings. This enables optical NMR detection without sacrificing the versatility of the traditional nuclear induction approach. While the signal-to-noise ratio is currently limited by the Brownian motion of the membrane as well as additional technical noise, we find it can exceed that of the conventional electrical schemes by increasing the electro-mechanical coupling strength. The electro-mechano-optical NMR detection presented here opens the possibility of mechanical parametric amplification of NMR signals. Moreover, it can potentially be combined with the laser cooling technique applied to nuclear spins.

quant-ph↗

arXiv2012

Optomechanical and Photothermal Interactions in Suspended Photonic Crystal Membranes

We present here an optomechanical system fabricated with novel stress management techniques that allow us to suspend an ultrathin defect-free silicon photonic-crystal membrane above a Silicon-on-Insulator (SOI) substrate with a gap that is tunable to below 200 nm. Our devices are able to generate strong attractive and repulsive optical forces over a large surface area with simple in- and outcoupling and feature the strongest repulsive optomechanical coupling in any geometry to date (gOM/2π ~ -65 GHz/nm). The interplay between the optomechanical and photo-thermal-mechanical dynamics is explored, and the latter is used to achieve cooling and amplification of the mechanical mode, demonstrating that our platform is well-suited for applications in low-power mass, force, and refractive index sensing as well as and optomechanical accelerometry.

physics.optics↗

arXiv2011

Designing evanescent optical interactions to control the expression of Casimir forces in optomechanical structures

We propose an optomechanical structure consisting of a photonic-crystal (holey) membrane suspended above a layered silicon-on-insulator substrate in which resonant bonding/antibonding optical forces created by externally incident light from above enable all-optical control and actuation of stiction effects induced by the Casimir force. In this way, one can control how the Casimir force is expressed in the mechanical dynamics of the membrane, not by changing the Casimir force directly but by optically modifying the geometry and counteracting the mechanical spring constant to bring the system in or out of regimes where Casimir physics dominate. The same optical response (reflection spectrum) of the membrane to the incident light can be exploited to accurately measure the effects of the Casimir force on the equilibrium separation of the membrane.

physics.optics↗

arXiv2011

Bonding, antibonding and tunable optical forces in asymmetric membranes

We demonstrate that tunable attractive (bonding) and repulsive (anti-bonding) forces can arise in highly asymmetric structures coupled to external radiation, a consequence of the bonding/anti-bonding level repulsion of guided-wave resonances that was first predicted in symmetric systems. Our focus is a geometry consisting of a photonic-crystal (holey) membrane suspended above an unpatterned layered substrate, supporting planar waveguide modes that can couple via the periodic modulation of the holey membrane. Asymmetric geometries have a clear advantage in ease of fabrication and experimental characterization compared to symmetric double-membrane structures. We show that the asymmetry can also lead to unusual behavior in the force magnitudes of a bonding/antibonding pair as the membrane separation changes, including nonmonotonic dependences on the separation. We propose a computational method that obtains the entire force spectrum via a single time-domain simulation, by Fourier-transforming the response to a short pulse and thereby obtaining the frequency-dependent stress tensor. We point out that by operating with two, instead of a single frequency, these evanescent forces can be exploited to tune the spring constant of the membrane without changing its equilibrium separation.

physics.optics↗