Paper has been an essential material in our daily life since ancient times. Its affordability, accessibility, adaptability, workability and its easiness of usage makes it an attractive structural material to develop many kind of technologies such as flexible electronics, energy storage and harvesting devices. Additionally, the scientific community has increased its interest on waste heat as an environmentally friendly energy source to support the increasing energy demand. Therefore, in this paper we described two affordable and flexible thermoelectric nanogenerators (TEGs) developed on paper substrates by the usage of simple micromachining and microfabrication techniques. Moreover, they exhibit mechanical stability and adaptability (through folding and cutting techniques) for a diverse set of scenarios where vertical or horizontal schemes can be conveniently used depending on the final application. The first TEG device, implemented on standard paper, generated a power of

Microbial fuel cells (MFCs) are an environmentally friendly method for water purification and self-sustained electricity generation using microorganisms. Microsized MFCs can also be a useful power source for lab-on-a-chip and similar integrated devices. We fabricated a 1.25 μL microsized MFC containing an anode of vertically aligned, forest type multiwalled carbon nanotubes (MWCNTs) with a nickel silicide (NiSi) contact area that produced 197 mA/m(2) of current density and 392 mW/m(3) of power density. The MWCNTs increased the anode surface-to-volume ratio, which improved the ability of the microorganisms to couple and transfer electrons to the anode. The use of nickel silicide also helped to boost the output current by providing a low resistance contact area to more efficiently shuttle electrons from the anode out of the device.

CitationDesign and characterization of ultra-stretchable monolithic silicon fabric 2014, 105 (15):154101 Applied Physics Letters

In today's traditional electronics such as in computers or in mobile phones, billions of high-performance, ultra-low-power devices are neatly integrated in extremely compact areas on rigid and brittle but low-cost bulk monocrystalline silicon (100) wafers. Ninety percent of global electronics are made up of silicon. Therefore, we have developed a generic low-cost regenerative batch fabrication process to transform such wafers full of devices into thin (5 μm), mechanically flexible, optically semitransparent silicon fabric with devices, then recycling the remaining wafer to generate multiple silicon fabric with chips and devices, ensuring low-cost and optimal utilization of the whole substrate. We show monocrystalline, amorphous, and polycrystalline silicon and silicon dioxide fabric, all from low-cost bulk silicon (100) wafers with the semiconductor industry's most advanced high-κ/metal gate stack based high-performance, ultra-low-power capacitors, field effect transistors, energy harvesters, and storage to emphasize the effectiveness and versatility of this process to transform traditional electronics into flexible and semitransparent ones for multipurpose applications.

To achieve higher power output from a thermoelectric generator (TEG), one needs to maintain a larger temperature difference between hot and cold end. In that regard, a stretchable TEG can be interesting to adaptively control the temperature difference. Here we show, the development of simple yet versatile and highly stretchable thermoelectric generators (TEGs), by combining well-known inorganic thermoelectric materials Bismuth Telluride and Antimony Telluride (Bi 2 Te 3 and Sb 2 Te 3) with organic substrates (Off-Stoichiometry Thiol-Enes polymer platform-OSTE, polyimide or paper) and novel helical architecture (double-arm spirals) to achieve over 100% stretchability. First, an OSTE-based TEG design demonstrates higher open circuit voltage generation at 100% strain than at rest,