Manufacturing Bits

19 August 2019

Chemical weapon sensors; earthworm chips; drug delivery devices. August 5th, 2019 – By: Mark LaPedus

Chemical weapon sensors
Using nanoelectromechanical system (NEMS) technologies and other parts, Sandia National Laboratories has developed a tiny gas chromatograph sensor for use in detecting toxic gases and chemical weapons.

Chemical identification involves the use of various instruments and systems. Larger systems are used in the lab. A portable version, called a mass spectrometer, is available in the market. But they less sensitive than the bigger lab-based instruments, according to Sandia.

Sandia has been working on smaller portable gas detection technologies using gas chromatography. Gas chromatography is a technique used to separate and analyze compounds.

Now, the agency has developed a small but fast gas chromatographic sensor using NEMS cantilever resonators for detection. A valve-based stop-flow modulator is also used in the system.

NEMS are like MEMS or microelectromechanical systems. MEMS are small devices with moving parts. Ink jet printer heads and pressure sensors are examples of MEMS devices. In comparison, NEMS integrate transistor-like nanoelectronics with moving parts.

With Sandia’s device, meanwhile, the unit has demonstrated the ability to separate and analyze a 29-component mixture in less than 7 seconds, according to Sandia. The system also detected compounds that simulate mustard gas and phosphonate-based nerve agents.

“With rapid analysis, operators can learn about an exposure to toxic gases in time for people to take personal precautions, evacuate an area and mitigate potential damage,” said Joshua Whiting, an analytical chemist at Sandia.

Earthworm chips
The Riken Center for Biosystems Dynamics Research (BDR) has developed a small MEMS-based valve device that is powered by earthworm muscle tissue.

The on-chip muscle-driven valve opens and shuts with high force and doesn’t require a battery. The device could one day be used for surgical implants and other applications.

The device combines MEMS technology with living materials, which falls under the category of bio-MEMS. Bio-MEMS can be a MEMS device, which is used in biological applications. One example of a bio-MEMS device is a sensor that is implanted into a living body. The sensor monitors a biological process.

Another application is an actuator. Part of a machine, an actuator controls a mechanism of a system. For example, it opens and closes a valve. Typically, actuators are MEMS-based devices. In contrast, a bio-MEMS actuator is powered by chemical means.

Riken’s bio-actuator involves a 2- x 2cm chip. There is a valve and a microfluid channel on the chip. The valve is controlled by the contraction and relaxation of an earthworm muscle via a chemical reaction.

The tissue provides high force, which could be sustained for minutes. A 1cm × 3cm sheet of earthworm muscle produces a force of about 1.5 milli-newtons over a two-minute period. The tissue reacts to a small amount of acetylcholine. “For muscles, the signal for contraction is the molecule acetylcholine—which is delivered by neurons—and the energy source is adenosine triphosphate (ATP)—which exists inside muscle cells,” according to Riken.

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