Double side polydimethylsiloxane gradient gratings as vectorial displacement sensing elements

•The orthogonal gradient optical grating structure fabricated on both sides of PDMS substrate pre-bent as a shape of ellipse.•Any vectorial displacement can be quantitatively characterized in both the x and y directions.•The error was small to be 0.4% and a resolution of 300μm-1.•The structure can be acted as a single element sensor applied for multi-axis integrated displacement sensors.

In this work, an orthogonal optical grating structure is demonstrated as a displacement sensing element. The grating is made with gradient periodicity and height on both sides of a polydimethylsiloxane (PDMS) substrate using an oxygen plasma treatment of prebent PDMS. Based on Fraunhofer diffraction effect, it is experimentally shown that any displacement can be quantitatively characterized in both the x and y directions with an estimated maximum error value of 0.4% and a resolution of 300 μm− 1. With this simple and low cost technology, it is proved that this structure can operate as a single element sensor for vectorial displacement signals, which can be applied for vectorial displacement measurement and multi-axis integrated displacement sensors.

Graphical abstractFabricating the double-side orthogonal gradient grating structure on the surface of PDMS to sense the vectorial displacement signalsFigure optionsDownload full-size imageDownload as PowerPoint slide