Embroidered sensors

Traditional sensors such as temperature sensors can be embroidered into a textile by using two primary methods: embroidering the host circuit board into the textile, or integrating the sensor into a fiber carrier. The first method involves using a specialized embroidery machine, where a pre-designed circuit board is stitched directly onto the fabric. This approach, while straightforward and quick, often results in a rigid and inflexible textile. To achieve this, the machine uses a digitized design, guiding the needle and thread to secure the circuit board onto the fabric. It's crucial to ensure that the thread take-up lever and rotary hook are properly synchronized to avoid thread breakage and maintain precise stitch formation.

The second method, embroidering sensors within a fiber carrier, is a more complex process. Here, the sensors are embedded within the fibers themselves before the embroidery process begins. This technique can lead to a more elegant and compliant solution, creating a textile that maintains its flexibility and comfort while carrying the functionality of the sensors. It's important to note that this method requires careful consideration of the thread tension, stitch density, and design complexity to ensure the integrity and functionality of the sensor. For example, adjusting the bobbin case tension is critical to prevent puckering and to maintain the sensor's connectivity throughout the textile. Additionally, selecting the appropriate type of embroidery thread, such as conductive yarns, is essential for maintaining the electrical properties required for sensor functionality.

However, the field of e-textiles is constantly evolving, and more form-fitting and haptic-sensitive textile-based sensors are being explored. These sensors leverage the properties of conductive fibers themselves such as large surface areas, variable resistivity, and geometric conformability. As a result, innovative solutions such as textile electrodes, stretch sensors, and sweat sensors can be reliably created. These sensors can be used in a variety of applications, ranging from wearable technology and smart clothing to healthcare and athletic performance monitoring. For instance, stretch sensors embedded in athletic wear can provide real-time feedback on muscle movements, while sweat sensors can monitor hydration levels and electrolyte balance during physical activities.

Learn More

For those interested in diving deeper into the world of e-textiles and embroidered sensors, the following resources provide excellent starting points:

• ASTM: Embroidered Conductive Fibers for Sensor Integration
• ISO: Smart textiles - Definitions, categorization, applications, and standardization needs
• ScienceDirect: An overview of smart technologies for clothing design and engineering

These resources offer comprehensive insights into the technical aspects of e-textiles, including the process of integrating sensors into fiber carriers, the challenges of creating form-fitting and haptic-sensitive sensors, and the future trends in this exciting field. They cover the historical evolution of smart textiles, the current state-of-the-art technologies, and future possibilities such as self-healing materials and energy-harvesting fabrics, which could revolutionize how we interact with textiles in everyday life.