## 1 Introduction  
Laser processing technologies make it possible to microfabricate a variety of materials without using vacuum and the harmful chemicals required for photolithography. By taking advantage of such features, laser-precise microfabrication has received a lot of attention in optoelectronics, biomedical fields, and so forth. While most of them are laser removal and surface modification technologies, since the 1980s, laser-induced forward transfer (LIFT) has been developed as a simple and unique additive manufacturing method [1]. By using LIFT, various substances, such as metals [2; 3; 4; 5], semiconductors [6], oxides [7; 8; 9], silver nanopaste [10; 11; 12], graphene [13], and biomaterials [14; 15; 16], can be printed even at a micron/submicron resolution under atmospheric and room-temperature conditions. The LIFT process generally involves the irradiation of a single laser pulse through a transparent support onto a donor material or a sacrificial layer that absorbs laser light, leading to laser-induced phenomena such as heating, melting, ablation, etc. In general, a laser-induced change induces a transient excitation field with high temperature and/or pressure, thus transferring the donor material toward a receiver substrate placed against the donor. With the advancement of beam delivery technologies such as digital mirror device and visualization methods, LIFT methods are progressing with higher accuracies and better phenomena elucidation [17; 18; 19; 20; 21; 22].  
Calcium phosphate (CaP) is the main inorganic constituent of bones and teeth. Certain types of CaP compounds, including hydroxyapatite, \(\beta\)-tricalcium phosphate, and octacalcium phosphate, exhibit both good biocompatibility and osteoconductivity [23]. Thus, various synthesis methods of CaP nanomaterials, including nanorods and nanowires [24] and nanopowders [25], have been developed [26]. Various methods of CaP coatings, such as plasma spray, pulsed laser deposition, and biomimetic processes [27; 28; 29], have also been developed to improve biocompatibility and osteoconductivity of medical devices. Among these CaP coating techniques, biomimetic processes are useful to produce multifunctional CaP coatings combined with biofunctional substances, such as proteins, since they are conducted under mild pseudo-physiological conditions [30]. However, conventional biomimetic processes are generally incapable of area-specific coating and take several hours to a few days [30] with a few exceptions [31].  
In our previous work, we demonstrated the rapid printing of cell adhesion protein fibronectin (Fn)-immobilized hydroxyapatite (Fn-apatite) microchips by applying LIFT to a shock-absorbing polydimethylsiloxane (PDMS) substrate [16]. Further, the conducted CHO-K1 cell culture experiments revealed the good cytocompatibility of the Fn-apatite microchips. However, a hard receiver substrate was not applicable to this technique; an applicable receiver substrate has been limited to a soft and shock-absorbing material, PDMS, owing to the brittle nature of apatite.  
In the present study, a novel LIFT process using a soft and shock-absorbing PDMS-coated transparent support, which we call LIFT with optical stamp (LIFTOP), was developed to print brittle CaP microchips even onto hard receiver substrates. Fn-immobilized CaP (Fn-CaP) donor films were prepared on an optical stamp (PDMS-coated transparent support) through the biomimetic process. Successful printing of the Fn-CaP microchips with a shape corresponding to a laser spot was demonstrated onto relatively hard receiver substrates, polyethylene terephthalate (PET) and human dentin, via the LIFTOP process. A cross-sectional interface between the Fn-CaP microchip and dentin was observed using a scanning electron microscope (SEM), revealing a good attachment without obvious gaps.