Tag Archives: polydimethylsiloxane

Cellulose-based nanogenerators to power biomedical implants?

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This cellulose nanogenerator research comes from India. A Jan. 27, 2016 American Chemical Society (ACS) news release makes the announcement,

Implantable electronics that can deliver drugs, monitor vital signs and perform other health-related roles are on the horizon. But finding a way to power them remains a challenge. Now scientists have built a flexible nanogenerator out of cellulose, an abundant natural material, that could potentially harvest energy from the body — its heartbeats, blood flow and other almost imperceptible but constant movements. …

Efforts to convert the energy of motion — from footsteps, ocean waves, wind and other movement sources — are well underway. Many of these developing technologies are designed with the goal of powering everyday gadgets and even buildings. As such, they don’t need to bend and are often made with stiff materials. But to power biomedical devices inside the body, a flexible generator could provide more versatility. So Md. Mehebub Alam and Dipankar Mandal at Jadavpur University in India set out to design one.

The researchers turned to cellulose, the most abundant biopolymer on earth, and mixed it in a simple process with a kind of silicone called polydimethylsiloxane — the stuff of breast implants — and carbon nanotubes. Repeated pressing on the resulting nanogenerator lit up about two dozen LEDs instantly. It also charged capacitors that powered a portable LCD, a calculator and a wrist watch. And because cellulose is non-toxic, the researchers say the device could potentially be implanted in the body and harvest its internal stretches, vibrations and other movements [also known as, harvesting biomechanical motion].

Here’s a link to and a citation for the paper,

Native Cellulose Microfiber-Based Hybrid Piezoelectric Generator for Mechanical Energy Harvesting Utility by
Md. Mehebub Alam and Dipankar Mandal. ACS Appl. Mater. Interfaces, 2016, 8 (3), pp 1555–1558 DOI: 10.1021/acsami.5b08168 Publication Date (Web): January 11, 2016

Copyright © 2016 American Chemical Society

This paper is behind a paywall.

I did take a peek at the paper to see if I could determine whether or not they had used wood-derived cellulose and whether cellulose nanocrystals had been used. Based on the references cited for the paper, I think the answer to both questions is yes.

My latest piece on harvesting biomechanical motion is a June 24, 2014 post where I highlight a research project in Korea and another one in the UK and give links to previous posts on the topic.

Gecko-type robots and Simon Fraser University

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I had to watch the (40 sec.) video a couple times to better marvel at the ‘gecko robot’ that a team of researchers at Simon Fraser University (Vancouver, Canada) have developed.

Here’s a little more information from the Nov. 2, 2011 posting by GrrlScientist on her Punctuated Equilibrium blog at the Guardian science blogs site,

Geckos are amazing animals for so many reasons, but their ability to climb glass windows is especially amazing since their sticky toes are not at all moist, as one would expect. Instead, gecko toes are dry, their adhesive ability the result of van der Waals forces. These are very weak, attractive forces that occur between molecules. For this reason, the gecko’s dry but sticky toe pads have long inspired scientists and engineers, especially mechanical engineers trying to design wall-climbing robots.

It looks like someone has finally succeeded. According to a hot-off-the-presses paper, a group of researchers from Simon Fraser University in British Columbia, Canada, have finally developed a robot – nowhere near as elegant in form as a gecko – that has the gecko’s ability to scale smooth walls and shuffle across ceilings without crashing down onto anyone’s head.

Here are some more details about the technology and the researchers (from the Nov. 1, 2011 SFU media release),

Known as the Tailless Timing Belt Climbing Platform (TBCP-11), the robot can transfer from a flat surface to a wall over both inside and outside corners at speeds of up to 3.4 cm per second. It is fitted with sensors that allow it to detect its surroundings and change direction.

Researchers mimicked the “dry, sticky toe pads” of the gecko by creating an adhesive using a material called polydimethylsiloxane (PDMS), manufactured as tiny mushroom cap-like shapes that are 17 micrometres wide by 10 micrometres high.

Meanwhile, tiny belts drive the robot’s tank-like moves, providing optimum mobility and expandability.

Lead author Jeff Krahn’s work on getting the robot to climb formed the bulk of his master’s thesis. The research was carried out together with engineering science assistant professor Carlo Menon.

This is the smoothest, most efficient climbing robot (stickybot) that I’ve seen. My August 26, 2011 posting featured  stickybots (with video) from  researchers at Stanford University.