Micronit is proud to highlight its central role in the SENTINEL project (PENTA 19017), which aimed to develop a next generation wearable platform for early health warning through non invasive sweat sensing. The project addressed one of the toughest challenges in wearable diagnostics: reliably detecting biomarkers from individuals at rest, where sweat production is extremely low.

Working closely with academic and industrial partners, Micronit led the work packages on:

• Chip device architecture
• Device assembly, including interfaces towards electronics and the finger-mounted wearable
• Microfabrication of the glass-based multilayer device
• Coating, surface engineering, bonding, and QC processes

Micronit's leadership in device architecture and integration

As work package leader, Micronit was responsible for the overall design of chip architecture, ensuring manufacturability, robustness, and compatibility with the novel transport mechanism based on electrowetting-on-dielectrics (EWOD) developed by TU/e and Philips.

Key architectural contributions included:

1. Glass-based collection plate with precision-engineered inlet holes

Using laser micromachining, Micronit manufactured glass plates containing arrays of 50 µm inlet holes, enabling sweat entry while minimizing dead volume and ensuring rapid filling, crucial for low sweat-rate operation.

2. Multilayer microfluidic stack

Micronit engineered and manufactured the multilayer assembly consisting of:

• Glass collection layer (inlet holes, hydrophobic coating, ground electrode metallization)
• EWOD layer (Cr/Au electrodes on glass, SiN + parylene dielectric stack)
• Spacer-defined microfluidic chamber (using precision-cut medical-grade tapes)

This multilayer design enabled seamless droplet creation, routing, sensing, and disposal.

3. Interfaces to electronics and wearable mechanics

Micronit co developed the interfaces connecting the chip to:

• The PCB via anisotropic conductive film (ACF) bonding
• The finger-mounted clip system for stable on skin attachment
• External electronics for EWOD actuation and capacitive sensing

Precision microfabrication enabled by Micronit technologies

Micronit applied its full suite of microfabrication capabilities to realize the complex chip:

• Laser micromachining using advanced direct glass drilling
• Metallization (Cr/Au) to define the electrodes
• Dielectric deposition to ensure reliable EWOD droplet transport using a double dielectric stack of silicon nitride and parylene-C
• Hydrophobic coating to enable low-voltage EWOD operation
• Photolithography to define the electrodes
• Bonding and assembly using laser cut PSA spacers and mask-aligner assisted bonding
• Quality control (QC) to ensure microfabrication accuracy and electrodes integrity

Enabling discretized microfluidics for ultra-low sweat rates

The SENTINEL system relies on discretized microfluidics, where individual sweat glands fill tiny collection holes that produce nanoliter droplets. These droplets are then transported using EWOD across the Micronit-fabricated chip.

This approach drastically reduces the required sample volume, bringing sweat-based biomarker detection into the clinically relevant timeframe of 15–30 minutes, even for individuals at rest.

Micronit’s fabrication precision was essential for:

• Consistent inlet geometries to achieve predictable Laplace pressures
• Smooth surface interfaces for repeatable EWOD droplet pinching
• Uniform dielectric properties enabling stable droplet actuation for long periods of time
• On-chip routing of droplets to biosensors or waste absorbers

A platform for future clinical applications

The SENTINEL device paves the way for measuring clinically important biomarkers in low sweat conditions, such as glucose, urea, lactate, cortisol, electrolytes, and therapeutic drugs.

With Micronit’s robust manufacturing approach, the device can evolve toward:

• Mass manufacturable glass or silicon platforms
• Integrated biosensors for multiplexed biochemical detection
• Fully wearable, wireless modules for clinical or home use

Micronit’s expertise in miniaturized diagnostics and scalable microfluidic manufacturing positions the company as a leading partner in next generation non invasive health monitoring solutions.

Bring your wearable diagnostic innovation to life

Whether you are developing point of care diagnostics, wearable biosensors, or microfluidic health monitoring devices, Micronit provides end to end support, from architecture design and prototyping to industrialization and scalable manufacturing. Contact us to explore how Micronit can accelerate your product development.