Featured Research

from universities, journals, and other organizations

Quartz crystal microbalances enable new microscale analytic technique

Date:
November 28, 2010
Source:
National Institute of Standards and Technology (NIST)
Summary:
A new chemical analysis technique uses the shifting ultrasonic pitch of a small quartz crystal to test the purity of only a few micrograms of material.

A NIST researcher prepares quartz crystal microbalance disks with samples of carbon nanotubes for microscale thermogravimetric analysis. Typical sample sizes are about 2 microliters, or about 1 microgram.
Credit: Kar/NIST

A new chemical analysis technique developed by a research group at the National Institute of Standards and Technology (NIST) uses the shifting ultrasonic pitch of a small quartz crystal to test the purity of only a few micrograms of material. Since it works with samples close to a thousand times smaller than comparable commercial instruments, the new technique should be an important addition to the growing arsenal of measurement tools for nanotechnology, according to the NIST team.

As the objects of scientific research have gotten smaller and smaller -- as in nanotechnology and gene therapy -- the people who worry about how to measure these things have been applying considerable ingenuity to develop comparable instrumentation. This new NIST technique is a riff on thermogravimetric analysis (TGA), an imposing name for a fairly straightforward concept. A sample of material is heated, very slowly and carefully, and changes in its mass are measured as the temperature increases. The technique measures the reaction energy needed to decompose, oxidize, dehydrate, or otherwise chemically change the sample with heat.

TGA can be used, for example, to characterize complex biofuel mixtures because the various components vaporize at different temperatures. The purity of an organic sample can be tested by the shape of a TGA plot because, again, different components will break down or vaporize at different temperatures. Conventional TGA, however, requires samples of several milligrams or more of material, which makes it hard to measure very small, laboratory-scale powder samples -- such as nanoparticles -- or very small surface chemistry features such as thin films.

What's needed is an extremely sensitive "microbalance" to measure the minute changes in mass. The NIST group found one in the quartz crystal microbalance, essentially a small piezoelectric disk of quartz sandwiched between two electrodes. An alternating current across the electrodes causes the crystal to vibrate at a stable and precise ultrasonic frequency -- the same principle as a quartz crystal watch. Added mass (a microsample) lowers the resonant frequency, which climbs back up as the microsample is heated and breaks down.

In a new paper.** the NIST materials science group demonstrates that their microbalance TGA produces essentially the same results as a conventional TGA instrument, but with samples about a thousand times smaller. They can detect not only the characteristic curves for carbon black, aluminum oxide and a sample organic fluid, but also the more complex curves of mixtures.

"We started this work because we wanted to analyze the purity of small carbon nanotube samples," explains analytical chemist Elisabeth Mansfield. More recently, she says, they've applied the technique to measuring the organic surface coatings biologists put on gold nanoparticles to modify them for particular applications. "Measuring how much material coats the particles surface is very hard to do right now," she says, "It will be a really unique application for this technique."

The prototype apparatus requires that the frequency measurements be made in a separate step from the heating. Currently, the team is at work integrating the microbalance disks with a heating element to enable the process to be simultaneous.


Story Source:

The above story is based on materials provided by National Institute of Standards and Technology (NIST). Note: Materials may be edited for content and length.


Journal Reference:

  1. Elisabeth Mansfield, Aparna Kar, Timothy P. Quinn, Stephanie A. Hooker. Quartz Crystal Microbalances for Microscale Thermogravimetric Analysis. Analytical Chemistry, 2010; 101116152615035 DOI: 10.1021/ac102030z

Cite This Page:

National Institute of Standards and Technology (NIST). "Quartz crystal microbalances enable new microscale analytic technique." ScienceDaily. ScienceDaily, 28 November 2010. <www.sciencedaily.com/releases/2010/11/101124153101.htm>.
National Institute of Standards and Technology (NIST). (2010, November 28). Quartz crystal microbalances enable new microscale analytic technique. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2010/11/101124153101.htm
National Institute of Standards and Technology (NIST). "Quartz crystal microbalances enable new microscale analytic technique." ScienceDaily. www.sciencedaily.com/releases/2010/11/101124153101.htm (accessed July 25, 2014).

Share This




More Matter & Energy News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

TSA Administrator on Politics and Flight Bans

TSA Administrator on Politics and Flight Bans

AP (July 24, 2014) TSA administrator, John Pistole's took part in the Aspen Security Forum 2014, where he answered questions on lifting of the ban on flights into Israel's Tel Aviv airport and whether politics played a role in lifting the ban. (July 24) Video provided by AP
Powered by NewsLook.com
Creative Makeovers for Ugly Cellphone Towers

Creative Makeovers for Ugly Cellphone Towers

AP (July 24, 2014) Mobile phone companies and communities across the country are going to new lengths to disguise those unsightly cellphone towers. From a church bell tower to a flagpole, even a pencil, some towers are trying to make a point. (July 24) Video provided by AP
Powered by NewsLook.com
Algonquin Power Goes Activist on Its Target Gas Natural

Algonquin Power Goes Activist on Its Target Gas Natural

TheStreet (July 23, 2014) When The Deal's Amanda Levin exclusively reported that Gas Natural had been talking to potential suitors, the Ohio company responded with a flat denial, claiming its board had not talked to anyone about a possible sale. Lo and behold, Canadian utility Algonquin Power and Utilities not only had approached the company, but it did it three times. Its last offer was for $13 per share as Gas Natural's was trading at a 60-day moving average of about $12.50 per share. Now Algonquin, which has a 4.9% stake in Gas Natural, has taken its case to shareholders, calling on them to back its proposals or, possibly, a change in the target's board. Video provided by TheStreet
Powered by NewsLook.com
Robot Parking Valet Creates Stress-Free Travel

Robot Parking Valet Creates Stress-Free Travel

AP (July 23, 2014) 'Ray' the robotic parking valet at Dusseldorf Airport in Germany lets travelers to avoid the hassle of finding a parking spot before heading to the check-in desk. (July 23) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

    Health News

      Environment News

        Technology News



          Save/Print:
          Share:

          Free Subscriptions


          Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

          Get Social & Mobile


          Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

          Have Feedback?


          Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
          Mobile: iPhone Android Web
          Follow: Facebook Twitter Google+
          Subscribe: RSS Feeds Email Newsletters
          Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins