A research project was undertaken to integrate Ultrasonic Consolitation (UC) and Direct-Write (DW) technologies into a single apparatus to fabricate embedded electrical systems within an ultrasonically consolidated metallic enclosure. Process and design guidelines were developed after performing fundamental research on the operational capabilities of the implemented system. In order to develop such guidelines, numerous tests were performed on both UC and DW. The results from those tests, as well as the design and process guidelines for the fabrication of an embedded touch switch, can be used as a base for future research and experimentation on the UC-DW apparatus. The successful fabrication of an embedded touch switch proves the validity of the described design and process parameters and demonstrates the usefulness of this integration.

Soft-Hard Active-Passive Embedded Structures (SHAPES) are composites that respond to the environments in which they are embedded. This reaction can be a mechanical actuation, but also an intrinsic computation that yields an adaptation as a result. The actuation capabilities primarily depend on the stiffness combination of the involved materials. Stiffness includes both material parameters (depending on the chosen material model, e.g., the Young's modulus) and geometry parameters (depending on the type of structure, e.g., the beam height). The active properties can be included using the Stimulus Expansion Model, which is based on the analogy of the active reponse to thermal expansion. SHAPES can be designed according to three different behaviors, Case I constrained, Case II combined and Case III free. In the current work, these cases, the modelling and design background, and various examples are presented.

Thin active elements can be added to rigid surfaces for the tuning of mechanical contact properties. The deformation of the active structures leads to the forming of arches. Depending on the forming of the arch, the force–displacement curve for contact becomes more or less steep. This can be understood as changing the interaction property between soft and hard. Herein, this concept is presented with hydrogels inside the active elements. Analytical derivations and finite-element simulation results for actuation and contact, based on the stimulus expansion model, are shown. This modeling approach appropriately captures the stimulus-dependent swelling properties of the material and can be easily applied in commercial finite-element tools. Special considerations are taken for the encapsulation of the active materials. A thin encapsulation foil allows 1) the use of swelling agents, such as water, without contaminating the contact objects. Furthermore, 2) appropriate water reservoirs for the swelling process can be included. The simulation results show that a surface softness tuning can be realized. The presented active material and dimensions are exemplary; the concept can be applied to other active materials for tuning surface interactions.