Reusable laser-absorbing layers for LIFT

The use of laser induced forward transfer (LIFT) techniques for printing materials for sensor and electronics applications is growing as additive manufacturing expands into the fabrication of functional structures. LIFT is capable of achieving high speed/throughput, high-resolution patterns of a wide range of materials over many types of substrates for applications in flexible-hybrid electronics. In many LIFT applications, the use of a sacrificial or laser-absorbing donor layer is required despite the fact that it can only be used once. This is because the various types of release layers commonly in use with LIFT are completely vaporized when illuminated with a laser pulse. A better solution would be to employ a reusable laser absorbing layer to which the transferable ink or material is attached and then released by a laser pulse without damage to the absorbing layer, therefore allowing its repeated use in subsequent transfers. In this work, we describe the use of two types of reusable laser-absorbing layers for LIFT. One is based on an elastomeric donor layer made from poly(dimethylsiloxane) or PDMS, while the other is based on a ceramic thin film comprised of indium tin oxide (ITO). These release layers have been used at NRL to transfer a wide range of materials including fluids, nanoinks, nanowires and metal foils of varying size and thickness. We will present examples of both PDMS and ITO as donor layers for LIFT and their reusability for laser printing of distinct materials ranging from fluids to solids.