Metal Pattern Transferring And Sensing Applications Based On Tunable Rigidity Stamp

Flexible electronic products are widely used in electronic skin,soft robot,stretchable sensor and man-machine interface in daily life.They are usually fabricated by transfer printing,3D printing,inject printing and silk screen process printing.The transfer printing technology can transfer the material from the donor to the surface of the receiver substrate by using a flexible stamp,which attracts wide attention because it can transfer metal structures and inorganic materials onto the flexible substrate.However,the stress mismatch between the flexible stamp and the material can damage the transferred material.So it is still a great challenge for the transfer of low tensile rates,fragile metal structures and other inorganic materials.Besides,rigid stamps are difficult to stretch and cannot be worn,which limits their applications in flexible electronics.In view of the above transfer process of metal structure transfer problems,this thesis reports a metal pattern transfer method based on tunable rigidity stamp,the elastic modulus of the stamp can be tuned to achieve nondestructive transfer of the metal film.Polymer stamps are fabricated by UV curing,and the precursor resins are synthesized by using polyurethane acrylate,isobornyl acrylate and photoinitiator819as raw materials.The rigidity of stamps can be tuned by soaking ethanol.This thesis studies the mechanical properties of the stamp before and after soaking in ethanol.After soaking in ethanol,the elastic modulus of the stamp has a maximum decrease of96.5%,from 63.31 MPa to 2.23 MPa,and the maximum strain is about 120%.In addition,the transmittance of the stamp film is over 90%in the visible light range,indicating that it has excellent transparency.In order to transfer the metal structure to the stamp,a UV curing process for stripping the stamp is proposed in this thesis.In the transfer process,the stamp is tuned to a high elastic modulus,so it can reduce the strain during the stripping of the metal film,and the metal patterns at the micron scale on the SiO₂ substrate can be transferred to the surface of the stamp without damage.The large-scale maple leaf and Hunan University emblem metal patterns can be transferred successfully via the process,and the pattern maintained high fidelity and resolution.The flexible metal film strain sensor is fabricated by soaking the stamp with metal electrode pattern in ethanol,which can monitor the finger,wrist and throat vocalizations.The metal film strain sensor shows high repeatability,sensitivity and stability.The method that tuning the elastic modulus of the stamp provides a new idea for the transfer printing process,which can effectively solve the fracture problem of metal materials and inorganic materials in the transfer process.It can promote the development of flexible electronic manufacturing technology.The sensor of the preparation of the stamp also shows great potential in the fields of medical and health monitoring.