Kirigami is an ancient Japanese art of folding and cutting paper; applied here to polymer sheeting (polyimide) using a laser alternating between different optical regimes to create a 3D spatial strain sensor. The laser parameters included:
1. Low power to inscribe carbonised strain sensitive tracks forming graphene sensor elements.
2. High laser power to cut around sensing elements to form a 3D topological shape to envelope 3D body parts such as the knee or amputated stump.
Carbon tracks were printed using a 1030 nm femtosecond laser with pulse duration of 550fs, optical power of 280m W and repetition rate 200 kHz. This low power beam carbonised the polymer to create strain-sensitive Laser Induced Graphene (LIG). The laser power was increased to 2.5W to ablate the polymer, at scan speeds of 200-300 mm/s. The increased power cut out the carbonised sensor elements.
Hence a conformational sensor was created by laser cutting and printing, of a two dimensional surface to create a 3D sensor of spatial shape deformation.
The Kirigami-inspired sensor is created in 2-D to sense 3D shapes and demonstrates digital switching of the Femtosecond laser between two beam parameter regimes to fabricate a strain sensor.