# Annular Microfluidic Meta-Atom Fusion-Enabled Broadband Metamaterial Absorber

## TL;DR

A new 3D-printed metamaterial absorber uses a unique microfluidic design to strongly absorb millimeter waves, useful for stealth and interference control.

## Contribution

A novel fused annular microfluidic meta-atom architecture for high-performance broadband millimeter wave absorption.

## Key findings

- FAMMA-based absorbers achieved ultra-low reflection loss of −42.1 dB.
- Effective absorption bandwidth reached 31.3 GHz with dual-band performance.
- The design significantly suppresses radar echo power and hides metallic targets.

## Abstract

Unique 3D-printed electromagnetic metamaterial absorber based on a fused annular microfluidic meta-atom architecture.Synergistic solid-liquid coupling effect of the unique three-dimensional orthogonal structure to achieve strong broadband absorption.High-performance broadband absorption for millimeter wave.

Unique 3D-printed electromagnetic metamaterial absorber based on a fused annular microfluidic meta-atom architecture.

Synergistic solid-liquid coupling effect of the unique three-dimensional orthogonal structure to achieve strong broadband absorption.

High-performance broadband absorption for millimeter wave.

The online version contains supplementary material available at 10.1007/s40820-025-02018-2.

Electromagnetic (EM) metamaterial absorbers (MMAs) with broadband absorption are of growing interest for applications such as stealth and EM interference mitigation. In this work, we present a novel 3D-printed MMA based on a fused annular microfluidic meta-atom (FAMMA) architecture, designed for W-band absorption. The FAMMA structure features three kinds of orthogonally fused annual meta-atoms, forming a complex 3D microfluidic meta-atom with intricate architecture. Fabricated via high-precision micro 3D printing technology, the FAMMA-based MMA exploits the synergistic solid–liquid coupling effect of the unique three-dimensional orthogonal structure to achieve strong broadband absorption. Three representative FAMMAs with different geometric dimensions have achieved ultra-low reflection loss (RL of − 42.1 dB), ultra-broadband effective absorption bandwidth (EAB of 31.3 GHz), and dual-band absorption (in 76.0–85.3 and 99.1–105.6 GHz), respectively. The underlying absorption mechanisms are elucidated by impedance matching theory and electromagnetic field distribution analyses. Application demonstrations show that the FAMMA-based MMA significantly suppresses radar echo power and renders metallic targets undetectable to both radar detector and radar imaging systems, highlighting its potential in stealth technology. Overall, this work establishes a new design concept for high-performance broadband millimeter wave MMAs, opening new avenue for future applications such as high-speed communication, through-wall sensing, and drone detection.

The online version contains supplementary material available at 10.1007/s40820-025-02018-2.