Not my area of expertise so don't know whether such a technology exists. The goal is to detect and quantify concentrations of biomolecules through SERS, in real time, and by using a miniaturised portable device.
As far as I know, it is not advisable to quantify a sample's concentration via SERS. It is a great tool to detect chemical signature of very small sample, but not for quantification. The reason is Raman peak intensity/postition/width may vary depending on concentration or orientation of molecule. But in case of SERS you would get variable intensity for same concentration, as the intensity will change drastically depending on the distance and orientation of sample from probe. This makes it very difficult to get a normalized data.
Snowy Range Instruments makes handheld miniature Raman spectrometers, and they are doing research in SERS. You may need to visit their website to get detailed information, and you may find what you want.
Here is their website.
http://www.wysri.com/products/
Hello!
My answer may be somewhat of a riddle, but I have come across with a very interesting article on the field, point out problems and solutions (along with some commercial info).
Hope it gives you some further insight, as well the responses to your questions.
Best,
Alcides Simão, AMRSC
http://dx.doi.org/10.1016/S1369-7021(12)70017-2
Hi Eder,
I agree with Saurabh on the problems outlined. If concentrations are large enough however, the molecular orientations will ‘average out’ with multiple measurements (and a large laser spot size) and allow a quantitative measurement. The sample (ie. SERS substrate) orientation and distance relative to the Raman device would need to be kept the same as whenever the calibration curve is plotted, as Saurabh points out.
The other problem is that the reproducibility of many SERS substrates (and homogeneity of Raman signal across any one sample) is not great, but again this may even out. In recent years there has been a focus on more ordered SERS substrates which provide better reproducibility at the cost of lower sensitivities (due to decreased nanometre-sized gaps).
Often any kind of quantitative measurement with SERS is dismissed as ill-advised. Maybe this is unfortunate? SERS has some advantages in terms of portability, speed and cost and may be viewed as complimentary to lab-based analytical options. I’ve tried to compare them here:
http://pubs.acs.org/doi/suppl/10.1021/ac5014095
Good luck! Would love to hear how you get on!
Best wishes
Mike
http://pubs.acs.org/doi/suppl/10.1021/ac5014095
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