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Research Services FAQ

What is the Non-invasive Micro-test Technique (NMT)?

The Non-invasive Micro-test Technology (NMT) is a method used to detect specific and/or selective ionic/molecular activities.

NMT® is a technology derived from VP (Vibrating Probe Technique). VP was first introduced by Dr. Lionel Jaffe and his students at MBL (Marine Biological Laboratory in Woods Hole, MA) in the early 1990s See Animation Illustration here

How does NMT work?

NMT measures the free-ion concentration gradient of a specified ion using a vibrating microelectrode. The electrode records the voltage at each measurement point representing the local concentration of that ion/molecule being measured. The flux (magnitude and direction) is derived from Fick’s law of diffusion: 

where J0 is the ion flux in the x direction, dc/dx is its concentration gradient and D is its diffusion constant. The direction of the ion’s flux is also derived from Fick’s law of diffusion that related the concentration gradient to the diffusion coefficient. 

. See Animation Illustration here


What kinds of ions/molecules can be measured using NMT?

So far, H+, Ca2+, K+, Na+, NH4+, Mg2+, Cd2+, Cl-, NO3- and H2O2, O2, IAA, Glutamate, Glucose are commercially available for research services.

If you want to measure any ions and/or molecules that are not on the list, please contact us for more information.

What kinds of samples have been measured so far?

Plant Samples:

Arabidopsis root, Arabidopsis pollen grains, Arabidopsis guard cells, Rice roots, Hybrid riceroots, Soybean roots, Corn roots, Barley roots, Wheat roots, Tomato roots, Populus roots, Poplar cells, Poplar protoplasts, Poplar vacuole, Apple roots, Pear fruit, Pear callus, Tobacco roots, Tobacco cells, Tobacco vacuole, Horsebeans, Broad bean mesophyll cells, Blue algae, Green algae, Enteromorpha, Iris root, Gymnosperm pollen tubes, Lily pollen tubes, Small red beans, Jujube tree roots, Cotton roots, Cotton fibers, Ginkgo fruit, Kandelia candel root, Aquatic plants, Myriophyllum, White thorn, China Limonium salt gland, Avicennia marina, Oak roots, and Eucalyptus roots.


Animal Samples:

Liver, Liver cells, Egg cell, Mice, Mites, Zebra fish, Medaka fish, Epithelial cells, Mosquito larvae, Osteoblasts, Tumor cells, Mouse islets, Gastric mucosa, Neurons, Cochlear cells, Mussel, Nasopharyngeal carcinoma cells, Flea Moina, Tadpoles, Mouse embryos, Frog skeletal muscle, Lung epithelial cells, Fish embryos, Bone, Tilapia, and Lymphocytes.


Microbial Samples:

Rhizobium japonicum, Mushrooms, Arbuscular mycorrhiza, and E.coli.


Material Samples:

Magnesiumalloy. Ceramics, and Carbon steel.

Why measure fluxes?

The external ionic/molecular Fluxes means:

  1. The nature and language of living organisms;
  2. The connections between physiological functions and functions of proteins and genes.
  3. It's real time and in situ.

What exactly is NMT measuring?

NMT is measuring selective/specific ionic/molecular fluxes close to your samples in pico (10-12) levels.

Please see other FAQs for "Why measure fluxes?"

What is the definition of flux as used here?

There are different definitions of flux in different areas. Here it is defined as: Diffusion flux, the rate of movement of molecules across a unit area (mol·m−2·s−1). (Fick's law of diffusion)

These fluxes are vectors at each point in space, and have a definite magnitude and direction. Also, one can take the divergence of any of these fluxes to determine the accumulation rate of the quantity in a control volume around a given point in space. For incompressible flow, the divergence of the volume flux is zero.

What is ion-selective electrode and how does it manage to select the specific ion?

The ion-selective electrode is actually a glass microelectrode with a short column of liquid ion exchanger (LIX, commercially called ionophores or cocktails) as shown in picture. The microelectrode performs its selectivity due to the ionophore. The ion-selective electrodes are freshly made for every single experiment.

Molecular selective/specific microelectrodes can be made of metals or nano materials.

Oxygen optrode is also available in our testing center.

What is the sensitivity of NMT?

picomoles/cm-2/s, 10-12moles of ions/molecules per cm2 per second, can be measured in most tests, sometimes, fecomoles/cm-2/s, 10-15moles of ions/molecules per cm2 per second, can be achieved in YoungerUSA (Xuyue Beijing) NMT Service Center.


What kind of data can I expect?

The following data/information will be provided after each test:

  1. What ion(s) and/or molecule(s) is/are being measured
  2. Static ionic/molecular concentrations at the points being measured
  3. Dynamic ionic/molecular fluxes at the points being measured which include
  • The directions of the motions of ions/molecules
  • How fast they are moving in terms of picomoles*cm-2*s-1

What does the 1-dimensional data look like?

Most data will be collected and presented in 1D and will look similar to the following.

(Numbers are for illustration ONLY)

What are the temporal and spatial resolutions?

The NMT can measure phenomena in a matter of seconds, and it can monitor the ionic/molecular activities for hours. Theoretically the samples can be kept monitoring as long as they are alive in a liquid media.

The spatial resolution is in micrometer scale, although the samples could be a single cell, a group of cells, tissues, organs or parts of intact organisms.

Why are there ions available on the Sigma-Aldrich website that are NOT on your list?

Most ionophores on the Sigma-Aldrich website are generally for the make of solid state ion selective electrodes. These electrodes are not suitable for NMT testings because of their required responding time.



The Liquid Ion Exchangers(LIX) which use these ionophores as major components are developed in house and characterized/tested for optimizing the operation of NMT.

What steps should be taken if we want to use your testing services?

Please fill out the online NMT Service Form. We will then work out a project plan with you, arrange the sample shipment, test the data, and then present it to you. It's that simple!

How to provide and prepare the living sample?

Although any size of samples can be used for NMT testing theoretically, namely the sample can be single cells, layer of cells, tissues, organs or parts of live intact organisms etc, there are limitations in practice, such as:

  1. Has to have the ability to be mounted and fixed on microscopes (either compound or dissecting microscopes)
  2. Must be in a liquid media optimized for both keeping the sample alive and flux measurements
  3. Has to have enough signal/noise ratio for the NMT system to measure

We have developed different mounting protocols for various samples.

How can we get our samples to you?

You can either ship your samples to our US Headquarters or ship it directly to our NMT Services Center.

Since we have culture equipment in the lab, it is usually preferred by both parties to have your samples cultured in our facility to avoid any possible damages that could occur during shipping process.

How are the chemicals and media handled?

Regular chemicals and media will be provided by the NMT Testing Center, so you won't have to worry. However, for some special reagents we may need to work out whether you will buy them and ship them to us or if we will buy them on your behalf for an additional charge.


Can you culture samples for us in your center?

Yes, we provide culturing services as an add-on service.

How much does your testing services cost?

The online NMT Service Form will automatically calculate the estimated cost for your project. We will then work out a project plan and a final cost with you.


How to pay for the services?

Payment Options

1. Purchase Order (P.O.)
2. Wire Transfer
3. Credit Card