Manufacturing Bits: March 10

Hi-tech pens
The University of California at San Diego has developed a hi-tech ballpoint pen.

Researchers have taken off-the-shelf ballpoint pens and filled them with bio inks. With so-called enzymatic-ink-based roller pens, users are able to draw biocatalytic sensors on a surface.

Researchers draw sensors capable of detecting pollutants on a leaf. (Source: UC San Diego)

The technology is referred to as “do-it-yourself” sensors. The pens could draw inexpensive electrochemical biosensors of any design on a wide variety of surfaces with minimal user training. In one application, the pen could draw renewable glucose sensor strips directly on the skin. Another application is to draw sensors on leaves to measure pollution.

The big challenge is to make inks that are safe. In this case, researchers are using a biocompatible polyethylene glycol as a binder. Graphite power is used to make the inks conductive. And they added chitosan to reduce bleeding on the skin. “Our new biocatalytic pen technology, based on novel enzymatic inks, holds considerable promise for a broad range of applications on site and in the field,” said Joseph Wang, the chairman of the Department of NanoEngineering at the University of California at San Diego.

Dial ‘M’ for medicine
The University of Michigan has devised a novel self-assembly process for fabricating tiny multiphasic particles.

The process enabled the production of the letter “M” in the English alphabet. In fact, researchers claim to have made the smallest “M” block in the world. In the real world, the technology could one day pave the way for medications that can target specific cells or deliver multiple drugs at different times and rates.

Magenta and blue delineate the different plastics in this two-layer Block M that University of Michigan made to demonstrate their new process. (Image: Sai Pradeep Reddy Kobaku)

The process enables particles that can be 10 or more layers thick, but they can have feature sizes down to 25nm. The mock Michigan logos are 115-by-160 microns and 3 microns thick.

The process starts with a silicon wafer, which has a liquid-repellent coating. Then, ultraviolet light is used. This, in turn, etches away the coating in the shape of the final particles. All told, this process enables the fabrication of a nonwettable surface, which is patterned with monodisperse domains of different sizes and shapes.

Then, the wafer is dipped into a polymer. The liquids self-assemble within the wettable domains. This, in turn, enables multiphasic particles. The templates can then be readily reused over 20 times.

The first application could be in chemotherapy. “Different types of cancer have different cell structures, and each type can internalize nanoparticles in a different way,” said Geeta Mehta, assistant professor of materials science and engineering, on the university’s web site. “We can easily tailor the shape and drug combinations of these new particles to each type of cancer so that they’re more effective against cancerous cells and less harmful to healthy cells.”

3D concrete
Using a 3D printer, the University of California at Berkeley has unveiled the world’s first and largest powder-based cement structure.

The structure resembles a freestanding pavilion, of which researchers call “Bloom.” The structure is 9 feet high and has a footprint that measures about 12 x 12 feet. It consists of 840 customized blocks. The material is a new iron oxide-free Portland cement polymer formulation.

Bloom was fabricated using 11 3D printers. Each brick has a pattern that allows for varying amounts of light to pass through.

3D-printed cement structure (Source: UC Berkeley)

Ronald Rael, associate professor of architecture, led the effort. The project obtained funding and collaborative support from the Siam Research and Innovation (SRI), the research and development division of Siam Cement Group (SCG). Additional support and materials were provided by startup Emerging Objects.

“While there are a handful of people currently experimenting with printing 3-D architecture, only a few are looking at 3-D printing with cement-based materials, and all are extruding wet cement through a nozzle to produce rough panels,” Rael said on the university’s Web site.. “We are mixing polymers with cement and fibers to produce very strong, lightweight, high-resolution parts on readily available equipment; it’s a very precise, yet frugal technique. This project is the genesis of a realistic, marketable process with the potential to transform the way we think about building a structure.”