AutoBio1000 Supports ECNU & KAIST in High-Impact Materials Research

Recently, Dr. Zhe Yu, Assistant Researcher at the School of Communication and Electronic Engineering / School of Integrated Circuits at East China Normal University (ECNU), together with Associate Professor U Bin from the Korea Advanced Institute of Science and Technology (KAIST), published a high-impact research paper in the top international journal *Journal of Materials Chemistry A*. The article is titled *“Multiple artificial mechanoreceptor-embedded waterproof ciliated E-skin via direct-ink-writing vertically 3D printing toward health management of seafarers”* (DOI: 10.1039/d5ta04906g).

In this study, the AutoBio1000 3D printer developed and manufactured by Soongon Technology efficiently completed the fabrication of high–aspect ratio micro-ciliated structures through vertical direct-ink-writing (DIW) 3D printing. This provided essential technical support for advancing the performance of the newly developed waterproof ciliated electronic skin (WCES).

Section I. Research Background: The urgent need for breakthroughs in health monitoring in maritime environments

More than 80% of global cross-border trade relies on maritime transportation. Seafarers work for long periods in enclosed and highly humid shipboard environments, making them susceptible to health problems such as abnormal blood pressure, circulatory disorders, and dysfunction of the autonomic nervous system. However, traditional wearable sensors often suffer from signal instability in high-humidity conditions, making continuous physiological monitoring difficult. Existing waterproof electronic skins (E-skins) also face limitations such as low sensitivity and complex fabrication processes, preventing them from meeting the practical needs of maritime applications.

To address these challenges, the research teams from ECNU and KAIST drew inspiration from the structural and functional characteristics of human epidermal hair and mechanoreceptors. They proposed a synergistic design that integrates vertically 3D-printed microciliated structures with embedded artificial mechanoreceptors. With its precise extrusion control and strong process compatibility, the Soongon AutoBio1000 DIW 3D printer served as the key equipment enabling this innovative design.

Concept Figure 1: Schematic illustration of epidermal hair and microciliated arrays.

(a) Diagram of epidermal hair and its interactions with multiple mechanoreceptors in the dermis, such as rapidly adapting and slowly adapting receptors.

(b) Design principle of the waterproof ciliated electronic skin (WCES), based on a polyurethane (PU) matrix embedded with carbon black (CB) and an ionic liquid (IL). Under applied pressure, particle sliding of the carbon black and ion migration within the ionic liquid mimic the responses of rapidly adapting and slowly adapting mechanoreceptors, respectively. A volatile solvent is used to formulate the polyurethane composite into a high–yield stress ink, enabling vertical 3D printing of microciliated structures through extrusion-based direct ink writing. During this process, rapid solvent evaporation contributes to structural stability at the surface.

Section II: Core Breakthrough: The SenGo AutoBio1000 3D Printer Enables High-Performance WCES Fabrication

1. Overcoming the Technical Challenge of Printing High Aspect Ratio Micropillars

Micropillars are the core structures that enable WCES to achieve both waterproofing and high sensitivity—the exposed portion forms a hydrophobic protective layer, while the embedded portion transmits mechanical signals. However, conventional direct ink writing (DIW) 3D printing is limited by the rheological properties of the ink, making it difficult to fabricate vertically oriented micropillars with high aspect ratios (H/F). The team optimized the ink formulation—using polyurethane (PU) as the matrix, with added carbon black (CB), ionic liquid (IL), and the volatile solvent DMF—and leveraged the precise parameter control capabilities of the SenGo AutoBio1000 3D printer to successfully achieve vertical 3D printing of micropillars. The resulting micropillars reached an aspect ratio of 3.55, and rapid solvent evaporation during printing formed a stable outer shell that prevented structural collapse, laying the foundation for WCES performance.

Figure 1: Characteristics of films made from different materials and the micropillar printing process.
(a) Electrical response of films made from different materials under pressure.
(b) Impedance Nyquist plots of films composed of PU, CB, and IL under different loading conditions.
(c) Photographs capturing key moments during vertical 3D printing of micropillars with different inks. From left to right, the CB content in the inks is 35 wt%, 40 wt%, and 45 wt%, respectively.
(d) Rheological properties of the three ink samples. Solid and dashed lines represent storage modulus (G') and loss modulus (G''), respectively.
(e) Apparent viscosity (η) of the ink samples as a function of shear rate.

2. Enabling the Dual Advantages of “Waterproofing + High Sensitivity”

The micropillar-array WCES fabricated via the AutoBio1000 3D printer demonstrates outstanding performance:

* Superb waterproofing: The micropillar structure increases the water contact angle of the material from 41.3° to 113.7°, forming a micron-scale air barrier. Water droplets roll off the surface easily, and after immersion in seawater (5% NaCl solution), tea, juice, and other liquids, the signal attenuation rate is at most 7.75%.

* Ultra-high sensitivity: Through stress concentration effects in the micropillars and dual-mode mechanical transduction using CB (simulating fast-adapting receptors, FA-R) and IL (simulating slow-adapting receptors, SA-R), the WCES achieves a sensitivity of 14.9 kPa⁻¹ in the 0–10 kPa pressure range, far exceeding existing waterproof sensors (0.001–1 kPa⁻¹).

* Excellent stability: After 10,000 pressure cycles and 6 days of accelerated aging tests (simulating six months of natural exposure), the WCES maintains stable electrical and mechanical performance, with a fracture toughness of 1.96 MJ/m³.

Figure 2. Microscopic structure and electrical performance of WCES.

(a) Photograph of the vertically printed micropillar array. Scale bar: 5 mm. The inset shows an optical microscopy image of the array. Scale bar: 1 mm.

(b) SEM image of a single micropillar and the corresponding elemental distribution maps obtained by EDS. Scale bars for the left SEM image and the enlarged SEM image are 300 μm and 20 μm, respectively.

(c) Photographs showing water contact angle measurements before and after printing the micropillar array on the film surface.

(d) Test photographs of water droplets rolling on the film surface with the micropillar array.

(e) Pressure-dependent electrical response spectra of WCES with micropillar arrays of different densities.

(f) Linear sensitivity of WCES with a 5×5 micropillar array over different pressure ranges.

(g) Comparison of sensitivity between the vertically printed WCES in this study (red) and previously reported waterproof sensors (blue) and conventional sensors (purple).

(h) Changes in WCES sensitivity over time after immersion in different solutions.

(i) ATR-FTIR spectra of the samples before and after accelerated aging tests.

Figure 3. Changes in other sensing performance of the water-carbon electrode sensor (WCES) before and after immersion, including dynamic range (DH) (a), reproducibility (b and c), response time (RT) (d), and limit of detection (LoD) (e).
(f) Stability test results of WCES after 10,000 cycles before and after immersion.
(g) Stress distribution of micropillars under 100 kPa pressure obtained via finite element analysis.
(h) Photographs showing micropillar overloading during the pressure loading–unloading process.

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