Dr Brice Le Borgne

Perfectly wrapping planar electronics to complex 3D surfaces represents a major challenge in the manufacture of conformable electronics. Intuitively, thinner electronics are easier to conform to curved surfaces but they usually require a supporting substrate for handling. The water transfer printing (WTP) technology utilizes water surface tension to keep ultrathin electronics floating flat without supporting substrate, enabling their conformal transfer on 3D surfaces through a dipping process. In many cases, however, the size of the microfabricated electronics is much smaller than the target 3D surface. This work proposes that such mismatch in size can be overcome by leveraging stretchable electronics in WTP. Stretchable electronics are compliant to in?plane stretch induced by water surface tension, hence can first self?expand in water and then be transferred onto 3D objects. Uniaxial and biaxial expansion ranging from 41% to 166% has been achieved without any externally applied tension. The results demonstrate that expansion?enhanced WTP is a promising fabrication process for conformable electronics on large 3D surfaces.

Electronic publishing usually presents readers with book or e-book options for reading on paper or screen. In this paper, we introduce a third method of reading on paper-and-screen through the use of an augmented book (?a-book?) with printed hotlinks than can be viewed on a nearby smartphone or other device. Two experimental versions of an augmented guide to Cornwall are shown using either optically recognised pages or embedded electronics making the book sensitive to light and touch. We refer to these as second generation (2G) and third generation (3G) paper respectively. A common architectural framework, authoring workflow and interaction model is used for both technologies, enabling the creation of two future generations of augmented books with interactive features and content. In the travel domain we use these features creatively to illustrate the printed book with local multimedia and updatable web media, to point to the printed pages from the digital content, and to record personal and web media into the book.

The need for the fabrication of a new generation of devices has developed with the next generation of ?home? engineers, which is resulting in an ever-increasing population interested in ?do-it-yourself? electronics and the Internet of Things. However, this new trend should not be done at the expense of the environment. Almost all previous studies, related to the low-temperature processing of devices, fail to highlight the extent of the impact that the synthesis of these technologies have on both the environment and human health. In addition, the substrates typically used, are also often associated with major drawbacks such as a lack of biodegradability. In this paper, we fabricate a simple RC filter using various domestically available printing techniques, utilising readily available materials such as: carbon soots (carbon black) as an electric conductor, and egg white (albumen) as a dielectric. These devices have been fabricated on both polyethylene terephthalate (PET) and paper, which demonstrated the same performances on both substrates and revealed that recyclable substrates can be used without compromise to the devices? performance. The filter was found to exhibit a cut-off frequency of 170 kHz, which made it suitable for high-frequency reception applications.

Electronic devices that emulate biofunctionalities, such as synaptic plasticity, present a promising route to versatile and energy-efficient neuromorphic computing systems. As the demand for rapid prototyping and environmentally friendly fabrication of such devices rises, there are significant incentives toward finding solutions for low-cost materials and flexible deposition techniques. The development of printed electronic devices is still at an infant stage, presenting a timely opportunity to investigate material robustness and routes to overcoming fabrication obstacles toward fully printed electronic synapses. In this work, a low-power, fully printed Ag (200 nm)/a-TiO2 (80 nm)/Ag (160 nm) memristive device is demonstrated. The first electrical characterization of early devices exhibits biomimetic properties with an indication of activity-dependent plasticity. The active material is derived from a simplified nanoparticle ink formulation developed in-house. The ink characterization confirms that the formulation fulfills the criteria for efficient jetting while exhibiting a dwell time of 4 months. Additionally, the common detrimental fabrication issues of layer cracks and control over uniformity here are both overcome. The ink optimization and the investigation of the electrical framework under which the memristive element responds synaptically present a favorable approach to alternative fabrication methods for future neuromorphic electronics.