A screen printable sacrificial fabrication process to realise a cantilever on fabric using a piezoelectric layer to detect motion for wearable applications

• A novel sacrificial material with low curing and removal temperatures.
• A novel method to release piezoelectric freestanding microstructures directly on fabrics using only screen printing.
• Cantilevers with a piezoelectric layer were achieved directly on fabrics.
• Using printed cantilevers as the basis of the sensor, in the form of motion sensors, has been demonstrated.
• The fabrication process would not affect the flexibility and breathability of the fabric using the interface layer which is only printed under the device.

Freestanding cantilevers have been fabricated by screen printing sacrificial and structural layers onto a standard polyester cotton fabric. By screen printing additional conductive and piezoelectric layers on to the cantilever it is possible to detect its displacement due to the movement of the underlying fabric. This type of freestanding structure cannot currently be fabricated using more conventional smart fabric manufacturing processes (e.g. weaving and knitting). Compared to such processes, screen printing offers the advantages of geometric design flexibility and the ability to simultaneously print multiple devices of the same or different designs. Furthermore, an expanding range of active inks exists from the printed electronics industry which can potentially be applied to create many types of smart fabric.To demonstrate the potential of this technology, a six-layer structure design has been printed onto fabric using a sacrificial material underneath the cantilever. The sacrificial layer is subsequently removed at 160 °C for 30 min to achieve a freestanding cantilever above the fabric. The devices have been worn on a human forearm and connected to a charge amplifier provided an example of simple motion detection.