Tag Archives: Rice University

bioengineers

This modified laser cutter can print complex 3D objects from powder


Rice University researchers have modified a commercial-grade CO2 laser cutter to create OpenSLS, an open source SLS platform.


Engineers at Rice University have modified a commercial-grade CO2 laser cutter to create OpenSLS an open source, selective laser sintering platform that can print complicated 3D objects from powdered plastics and biomaterials.

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As impressive as that may be, what really sets this system apart is its cost. OpenSLS can be built for under $10,000, compared to other SLS platforms typically priced in the ballpark of $400,000 and up. (That’s at least 40 times less than its commercial counterparts.) To make this a reality, this DIY device is equipped with low-cost hardware and electronics, including Arduino and RAMBo boards. The Rice team provides more detail around specs and performance in PLOS ONE.

“SLS technology is perfect for creating some of the complex shapes we use in our work, like the vascular networks of the liver and other organs,” explains Jordan Miller, an assistant professor of bioengineering and the study’s co-author. He adds that commercial SLS machines generally don’t allow users to fabricate objects with their own powdered materials, which is something that’s particularly important for researchers who want to experiment with biomaterials for regenerative medicine and other biomedical applications.

To test their concept, the team demonstrated that OpenSLS is capable of printing a series of intricate objects from both nylon powder — a commonly used material for high-resolution 3-D sintering — and from PCL, a nontoxic polymer that’s typically used to make templates for studies on engineered bone.

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It should be noted, however, that OpenSLS works differently than most traditional desktop 3D printers, which create objects by extruding melted plastic through a nozzle as they trace out two-dimensional patterns and 3D objects are then built up from successive 2D layers. On the contrary, an SLS laser shines down onto a flat bed of plastic powder. Wherever the laser touches powder, it melts or sinters the powder at the laser’s focal point to form a small volume of solid material. By tracing the laser in 2D, the printer can fabricate a single layer of the final part. After each layer is complete, a new one is laid down and the laser is reactivated to trace the next layer.

The best way to think of this process, says Miller, is to think of “finishing a creme brulee, when a chef sprinkles out a layer of powdered sugar and then heats the surface with a torch to melt powder grains together and form a solid layer. Here, we have powdered biomaterials, and our heat source is a focused laser beam.”

The professor, who happens to be an active participant in the burgeoning Maker Movement, first identified commercial CO2 laser cutters as prime candidates for a low-cost, versatile SLS machine three years ago. According to Miller, that’s because the cutter’s laser already possessed the right wavelength and perfectly suitable hardware for controlling power and its axes with precision.

Intrigued? You’ll want to see it in action below, and then head over to the team’s Wiki page and GitHub repository to delve a bit deeper.

[Images: Rice University]

Glove

The Hands Omni glove will let gamers feel virtual objects


Rice University students create a feedback wearable device for virtual reality environments.


Though virtual reality has grown by leaps and bounds over the years, a vast majority of recent advancements have been focused around the audible and visual senses — touch not so much. With that in mind, a team of Rice University engineering students has unveiled a haptic glove that lets a wearer feel simulated objects as if they’re actually there. In other words, to make virtuality reality even more “real.”

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The Hands Omni glove was designed to provide a way for gamers and others interested in VR to experience the environments they inhabit through the likes of three-dimensional heads-up displays. The prototype — which was introduced at the George R. Brown School of Engineering Design Showcase and developed in collaboration with gaming technology company Virtuix — works by providing force feedback to a user’s fingertips as they touch, press or grip things inside their virtual world.

The right-handed glove is comprised of inflatable bladders that sit underneath each finger, and expand and contract as necessary. What’s more, the wearable is wireless to allow the user to have a full-range of motion without ever having to worry about unwanted cables getting in the way during gameplay.

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While the team’s agreement with its sponsor Virtuix means the underlying technology of the glove must remain top-secret, the students did reveal that an Atmel based Arduino is at the heart of its system. Its creators also point out that programmers will find it pretty straightforward to implement the glove’s protocols in future games and other immersive projects.

Basically, as a game is played, signals are sent from a computer using Arduino over to its proprietary system, which in turn inflates each of the individual bladders. The fingers are individually addressable, though pressure on the ring and little fingers is triggered as one unit in the prototype.

For example, say you come across an apple, a baseball or even some sort of weapon in a Call of Duty-style game, and want to pick it up, the Hands Omni will enable you to simply reach out and make it so that it’s as if you are touching a physical object.

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The Hands Omni glove weighs around 350 grams (just over 12 ounces), which its creators say makes it light enough to be comfortably worn on a hand for long sessions without ever noticing it’s there.

“We had our own constraints based on testing to determine the amount of perceptible weight that could be strapped to your fingers, arms, legs and limbs — the maximum weight that is perceptible to users — and we came up with 660 grams on the forearm and much less than that on the back of the hand or on the fingers,” explains team member Kevin Koch. “We wanted as much mass as far back on the hand as possible, and that’s exactly what we’re doing.”

Intrigued? You can head over to the project’s official page here.

ricefleixblebattery

Flexible battery eyes next-gen wearables

Rice University researchers have created a flexible battery that could potentially power future generations of wearable devices. 

Developed by Rice chemist James Tour and his colleagues, the design comprises flexible material with nanoporous nickel-fluoride electrodes layered around a solid electrolyte.

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The flexible power source delivers battery-like supercapacitor performance, combining the best qualities of a high-energy battery and a high-powered supercapacitor – without the lithium found in current commercial batteries.

According to Rice postdoctoral researcher Yang Yang, the electrochemical capacitor is about a hundredth of an inch thick, although it can be scaled up by increasing the size or adding layers. In terms of slimming down the battery, Tour believes standard manufacturing techniques will likely allow the battery to become even thinner. 

In tests, the students found their square-inch device held 76 percent of its capacity over 10,000 charge-discharge cycles and 1,000 bending cycles.

As Tour notes, his team set out to find a material that offered the flexible qualities of graphene, carbon nanotubes and conducting polymers – all while possessing significantly higher electrical storage capacity typically found in inorganic metal compounds. Unfortunately, inorganic compounds have, at until recently, lacked real flexibility.

“This is not easy to do, because materials with such high capacity are usually brittle,” he said.

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“And we’ve had really good, flexible carbon storage systems in the past, but carbon as a material has never hit the theoretical value that can be found in inorganic systems, and nickel fluoride in particular.”

Yang expressed similar sentiments.

“Compared with a lithium-ion device, the structure is quite simple and safe. It behaves like a battery but the structure is that of a supercapacitor,” he explained. “If we use it as a supercapacitor, we can charge quickly at a high current rate and discharge it in a very short time. But for other applications, we find we can set it up to charge more slowly and to discharge slowly like a battery.”

To create the battery/supercapacitor, Tour’s team deposited a nickel layer on a backing, subsequently etching it to create 5-nanometer pores within the 900-nanometer-thick nickel fluoride layer (facilitating a high surface area for storage).

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Once the researchers removed the backing, they sandwiched the electrodes around an electrolyte of potassium hydroxide in polyvinyl alcohol. Testing found no degradation of the pore structure even after 10,000 charge/recharge cycles. Similarly, the scientists confirmed no significant degradation to the electrode-electrolyte interface.

“The numbers are exceedingly high in the power that it can deliver and it’s a very simple method to make high-powered systems,” Tour added. “We’re already talking with companies interested in commercializing this.”