Manufacturing Bits: Aug. 13

Crawling and climbing robots; MRI lithography; salty chips.


Crawling And Climbing Robots
The field of autonomous robotics is generating interest, as these systems can explore areas and perform functions that are risky and inaccessible to humans.

The University of California at San Diego and EPFL separately have developed new autonomous robots for a range of applications. For example, UC San Diego has developed a robot designed to scoot along utility lines like a monkey. The so-called SkySweeper robot can search for damage and make repairs on power lines. A video can be seen here.

Source: UC San Diego.

Made from parts on a 3D printer, SkySweeper could be made for less than $1,000. The robot is V-shaped with a motor-driven “elbow” in the middle. Its ends are equipped with clamps that open and close in order to move down the power line. It can be outfitted with induction coils to harvest energy from the power line itself, making it possible for the robot to stay deployed for weeks or months.

“Current line inspection robots are large, complex, and expensive. Utility companies may also use manned or unmanned helicopters equipped with infrared imaging to inspect lines,” said Nick Morozovsky, a graduate student in mechanical engineering on the university’s Web site.

Separately, EPFL’s Laboratory of Intelligent Systems is developing a flying robot that has the ability to move on the ground by using its wings only. In effect, the wings also act as legs, allowing it to move on rough terrains.

The robot is the first prototype of the Deployable Air Land Exploration Robot (DALER) project. This effort aims at designing robots for exploration, search-and-rescue and monitoring of the environment. The plastic prototype is made using a 3D printer. The total weight of the robot is 450 grams for a wingspan of 60 cm. The robot can move forward at speeds of 0.2 m/s (0.7 BL/s), and can rotate on spot at 25°/s. It can fly at about 14m/s for about 30 minutes in forward flight.

MRI Litho
In medical applications, magnetic resonance imaging (MRI) allows nondestructive imaging inside opaque objects at high resolutions. The inverse of MRI provides an approach to lithography to enable arbitrary patterns with high contrast.

Researchers from Texas A&M University call this magnetic resonance lithography. In fact, for some time, the university has been working on molecular-scale MRI technology.

In Texas A&M’s magnetic resonance lithography technology, a pattern is transferred to a thin material, which consists of electron or nuclear spins. A line is written by applying the magnetic gradient and microwave pulses, which resemble an MRI scan. Then, microwave and optical readout pulses are applied to expose the photoresist.

This is accomplished using materials exhibiting optically detected magnetic resonance (ODMR) technology. One example of such materials is nitrogen-vacancy (NV) color centers in diamonds, according to researchers.

To write arbitrary 2D patterns, multiple lines are simply written in sequence. Researchers have used simulations to show magnetic resonance lithography is feasible, but more work is required to demonstrate that the pattern can be transferred to the photoresist. The next step is to develop resists that work with ODMR materials with better contrast, according to researchers.

Salty Chips
Silicon nanostructures can be used in chips, thermoelectric materials and electrochemical energy devices. But in general, these nanostructures are difficult and expensive to make.

Oregon State University has identified a compound that could enable a new class of silicon nanostructures–common table salt.

Researchers have developed a method that mixes sodium chloride and magnesium with diatomaceous earth. In a system, the temperature was turned to 801 degrees Centigrade. The salt melted and absorbed heat in the process. A solid melting into a liquid absorbs heat, while keeping the nanostructures from collapsing.

Using a combination of heat and magnesium is called a magnesiothermic reaction. A magnesiothermic reduction can convert silicon dioxide into silicon nanostructures. By employing table salt as a heat scavenger for the magnesiothermic reduction, researchers demonstrated an effective way to convert diatom silicon dioxide and silicon dioxide/germanium dioxide into a nanoporous silicon and silicon/germanium composite, respectively, according to researchers.

Fusion of the table salt during the reaction consumes heat that otherwise collapses the nano-porosity of products and agglomerates silicon domains into large crystals. “This could be what it takes to open up an important new industry,” said David Xiulei Ji, an assistant professor of chemistry in the OSU College of Science, on the university’s Web site.

“The use of salt as a heat scavenger in this process should allow the production of high-quality silicon nanostructures in large quantities at low cost,” he said. “If we can get the cost low enough many new applications may emerge.”

—Mark LaPedus