Compact Ultrasonic Transducer Integrated Dual-Domain Metamaterials ‘MiPAL’ Achieve Ultra-Broadband Directional Audio Generation

August 17, 2026

PMC Unknown

Overview

Researchers have developed MiPAL, a compact ultrasonic transducer co-integrated with dual-domain metamaterials, for highly directional audio generation. Unlike conventional parametric array loudspeakers, MiPAL uses a single piezoelectric driver and co-designed acoustic metasurface and elastic meta-units to achieve a simple, cost-effective, and highly integrated architecture. Experiments demonstrate that MiPAL generates ultra-broadband directional sound over four octaves (500 Hz to 10 kHz), laying the foundation for immersive audio and extended reality applications.

In Depth

Key Findings

Researchers have innovatively developed a device named “MiPAL” (Micro-parametric Array Loudspeaker) that integrates a compact ultrasonic transducer with dual-domain metamaterials, enabling highly directional and ultra-broadband audio generation. This breakthrough significantly expands the possibilities for immersive audio experiences and extended reality (XR) applications.

Technical / Clinical Details

Unlike conventional parametric array loudspeakers, which typically require complex multiple driver arrays, MiPAL achieves a simple, cost-effective, and highly integrated architecture by combining a single piezoelectric driver with co-designed acoustic metasurfaces and elastic meta-units. The acoustic metasurface plays a crucial role in precisely controlling sound wave propagation, generating and modulating ultrasonic beams. The elastic meta-units contribute to structural stability and optimize vibration characteristics. These components are manufactured using SLA 3D printing technology with photo-polymer UV resin, with their precise design underpinning MiPAL’s high performance. Experimental results demonstrated that MiPAL can generate highly directional sound over an ultra-broadband range, spanning more than four octaves from 500 Hz to 10 kHz. This capability enables “private audio,” delivering sound to specific listening zones without affecting other areas.

Background & Context

In audio technology, particularly in directional loudspeakers, there is a growing need to deliver sound to specific locations to reduce noise and provide personalized listening environments. This is especially important in office settings, museums, public spaces, and next-generation immersive entertainment (VR/AR). Traditional directional audio technologies often rely on acoustic lenses or large speaker arrays, leading to challenges in device size and increased cost. Metamaterial technology is gaining attention as an innovative approach that can overcome these challenges, enabling compact and high-performance acoustic devices.

Strategic Significance & Outlook

The advent of MiPAL opens new horizons for audio technology applications. It promises enhanced immersive audio experiences, realistic acoustic feedback in extended reality (XR) devices, targeted information delivery to specific individuals, and effective sound masking in noise-sensitive environments. Future research will focus on directional control over an even broader frequency range, increasing sound pressure levels, and optimizing manufacturing costs. This technology is poised to drive the miniaturization and performance enhancement of acoustic devices, redefining future sound interactions.

Source: https://pmc.ncbi.nlm.nih.gov/articles/PMC13385809/

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