Microstructured elastomeric surfaces with reversible adhesion and examples of their use in deterministic assembly by transfer printing

Abstract

Reversible control of adhesion is an important feature of many desired, existing, and potential systems, including climbing robots, medical tapes, and stamps for transfer printing. We present experimental and theoretical studies of pressure modulated adhesion between flat, stiff objects and elastomeric surfaces with sharp features of surface relief in optimized geometries. Here, the strength of nonspecific adhesion can be switched by more than three orders of magnitude, from strong to weak, in a reversible fashion. Implementing these concepts in advanced stamps for transfer printing enables versatile modes for deterministic assembly of solid materials in micro/nanostructured forms. Demonstrations in printed two- and three-dimensional collections of silicon platelets and membranes illustrate some capabilities. An unusual type of transistor that incorporates a printed gate electrode, an air gap dielectric, and an aligned array of single walled carbon nanotubes provides a device example.

Thermal diffusion boron doping of single-crystal natural diamond

“…It is also expected that higher crystal quality can be obtained using the thermal diffusion method as opposed to the ion implantation method after finishing the doping process. By using the transfer printing method, clean interfaces are ensured and importantly, selective doping (to be seen later), via deterministic transfer printing of SiNMs of different sizes to the selective areas on the diamond surface, is made easy and precise 21 . The selective doping enabled by selective transfer printing, while applicable to any size and shape of diamond plates (in contrast to direct wafer bonding), leads to a planar doped structure that can facilitate device implementations.…”

Inorganic semiconductor nanomaterials for flexible and stretchable bio-integrated electronics

“…In an example of this process, (Figure 3a) NMs (or NWs) are prepared on and anchored to source substrates in a way that retains their lithographically defined locations even after complete undercut etching. 45,69,70 Contact of an elastomeric stamp with matching features of relief on its surface leads to van der Waals forces that can be sufficiently large to break these anchors and lift selected collections of NMs onto the surface of the stamp when it is peeled away. 45,69,70 A stamp, inked in this manner, can deliver the NMs, in a single impression, to a substrate of interest.…”

“…45,69,[71][72][73][74] An important consideration is in control over the adhesion between nanomaterials and the surfaces of the stamps, in ways that allow switching from strong to weak states for retrieval and printing, respectively. 69,70,75,76 Various approaches, ranging from those that exploit viscoelastic effects 69,75 to interface shear loading 76 to pressureinduced contact modulation, 70,77 can be effective. In many cases, separate adhesive layers on the receiving substrate can further facilitate the printing.…”

Geckoprinting: assembly of microelectronic devices on unconventional surfaces by transfer printing with isolated gecko setal arrays

“…Several promising strategies for avoiding these adverse effects when transfer printing the microelectronic devices involve the use of artificial controllable adhesives that rely on either the elastic recovery of soft elastomers [20] or on the direction-dependent mechanical behaviour of micropillars [20][21][22]. These two types of controllable adhesives were inspired by aphids and geckos, respectively.…”