LNNano - Brazilian Nanotechnology National Laboratory

In-house Research

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Scientific programs and internal research

Internal research activities at LMF encompass a large broad of platforms and activities in microfabrication and micrometric scale:

  • Micro electro-mechanical systems (MEMS) and different integrated architectures and solutions for energy processing, power management and data communication;
  • Microsensors for different sensing modalities (as temperature, pressure, inertial forces, chemical and microbiological species, magnetic fields, light, color, radiation) and for process monitoring and controlling as in the chemical, pharmaceutical, food and fuel industries;
  • Microreactors and low impact or minimally invasive microfluidic devices for health, agricultural and environmental uses;
  • Point-of-care microemulsification dispositives for analytical determinations;
  • Optical lithography;
  • Thin-film deposition.

LMF also performs chemical- and electro-transformation devices prototyping and assists companies in start-ups of new processes related to these research fields.

Main research topics

  1. Point-of-care (POC) platforms
  2. New techniques for microfabrication substrates
  3. Chemical analytical devices

 

  1. Point-of-care (POC) platforms
  • Why LMF is dedicating R&D efforts to POC?

Lives of many patients on health facilities, accident sites or even at remote locations could be spared if successful clinical decisions could be quickly taken based on measurement results from inexpensive and simple point-of-care diagnostic tests. The amplitude of point-of-care technology also extends to industrial quality control, environmental monitoring, medicines delivery and all sorts of analytical determinations.

  • What is the contribution of LMF on the field?

The LMF team, supported by the Brazilian oil & gas company Petrobras, have developed in 2013 a new method for analytical determinations that can be easily applied to POC platforms, denominated MEC (microemulsification method).

  • What is the microemulsification method (MEC)?

MEC relies on the effect of the concentration of an analyte of interest over the entropy of a dispersion, which affects the formation of microemulsions. The method allows the determination of concentration of the analyte on the media based on the measurement of the turbidity of the emulsion, which is dependent of the amount of nanodroplets generated and present on the emulsion. See an example of microemulsification at Figure 1.

  • Why to build and operate a POC device based on MEC?

MEC is a very reliable, precise and fast technique for the determination of concentration of a large group of species of different natures. Concentration readings are visual and do not require special training of the operator. Prototypes and large-scale production have cost advantages compared to other testing platforms due to the low consumption on reagents or chemicals and the simplicity of assembling into portable devices.

  • Examples of application of the technology by LMF
  • Determination of water in ethanol fuels;
  • Determination of monoethylene glycol in liquefied natural gas.

For information on the latest studies of LMF team in this topic, consult:

Lima, R. S.; Shiroma, L. Y.; Teixeira, A. V. N. C.; De Toledo, J. R.; Do Couto, B. C.; De Carvalho, R. M.; Carrilho, E.; Kubota, L. T.; Gobbi, A. L. Microemulsification: An Approach for Analytical Determinations, Analytical Chemistry, v. 86, p. 9082, 2014.

Figure 1. The generation of nanodroplets in thermodynamically stable dispersions of microemulsions (right in photo) allows complex chemical analyses by visually detect the change of turbidity from emulsions or Winsor systems (left in photo). The platform relies on the effect of the analyte over entropy of the dispersions. It combines simplicity (bypasses instrumental detection or qualified operators), rapidity, low consumption of chemicals, and portability with high analytical performance, representing a potential alternative for the development of point-of-care technologies.

  1. New techniques for microfabrication substrates
  • Nature of microfabrication substrates.

Construction, performance and final application of microfabrication devices are dependent on the nature of the substrate. Generally, substrates for microfluidics devices have been fabricated from glass due to its advantages comparative to other materials, as (i) high optical transparence, (ii) chemical inertia, (iii) good solvent resistance, (iv) thermal stability, (v) robustness in handling and (vi) adequacy for nanoscale techniques, allowing laser writing, etching and high resolution lithography. Also, glass offers less risk of thermal stress and cracking / shrinkage of metals and semiconductors deposited on the surface of the substrate when performing electrical or electrochemical experiments.

  • Why LMF is dedicating efforts to the R&D of microfabrication substrates?

The increase of the complexity of microfabricated devices and the necessity of reducing microfabrication costs to guarantee commercial competitiveness of these devices are posing limitations to the use of glass as a substrate. Also, new developments in micro total analysis systems (mTAS), lab-on-a-chip (LOC) and MEMS platforms are constrained by the difficulty to integrate functional components to glass substrates.

  • What is the contribution of LMF in the field?

LMF has been working on methods to reduce costs and complexity of the bonding step for glass microchips. One successful result obtained by the team is the development of the sacrificial adhesive bonding (SAB) method. SAB is based on the action of an adhesive layer that seals the slides onto one another and simultaneously generates microfluidic channels with glass-like properties. The layer is later removed from the system by using a proper developer. The main steps of the methodology can be seen at Figure 2.

  • What are the advantages of SAB?

SAB is a simple, fast, low-cost procedure and is compatible for ultra-large scale integrated (ULSI) processes and thin-film integration.

  • Examples of application of the technology by LMF

LMF team has recently deposited the patent application number BR 10 2014 012630 9 at the Brazilian National Institute of Intellectual Property (INPI) which contains examples of the application of SAB method.

Additional information on the latest studies of LMF team in this topic can be accessed by emailing Angelo L. Gobbi or Renato S. Lima.

Figure 2. Steps for bonding (a-f) and deposition of opaque film (OF) into microchannel (g-l). OF protects the SU-8 from UV that is not cured (d) allowing its selective development only in microchannel regardless the development time (e). Glass (a,g), deposition of SU-8 over this wafer and then prebake (b), preliminary bonding against the glass substrate with the roof of the microchannel coated with a thin film of Al (golden in the drawings) (c), cure of the resist just around the microchannel after UV exposure and PEB (resist under the channel is no cured because it is protected from UV by the Al mask) (d), removal of the uncured SU-8 and, next, of the thin film by pumping specific solvents (blue in the drawing) (e), and final chip showing residual SU-8 in the sidewalls (f). Deposition of positive resist over this slide and then prebake (h), UV exposure, development producing the mask for microchannel pattern transfer, and hard bake (i), glass etching (j), deposition of OF by sputtering over all of the slide (k), and lift-off with the thin film only into the etched cavity (f). Features not drawn to scale. In addition, the sidewalls in etched glass commonly are not vertical, but rounded.

  1. Chemical analytical devices
  • Why LMF is dedicating R&D efforts to chemical analytical devices?

Instrumental detection methods for fast and simple determination of analytes of interest in a large group of substances are becoming essential to monitor the quality and the performance of commercial products and to attend the challenging needs and demands of some key markets, especially the ones dealing with the directly selling of goods to the consumers.

  • What is the contribution of LMF in the field?

LMF team is working on the development of portable test tools for rapid determination of analytes in different liquid or gaseous media with high precision in measurement, large range of operation, robustness and low production and operational cost, which can be as much as independent of chemicals and reagents and easily prototyped.

  • Examples of application of the technology by LMF

Ethanol fuel adulteration by water is a common problem in countries whose automotive industry is largely ethanol-dependent. Also, large fuel contaminations can damage vehicle parts and/or compromise performance. For solving this, LMF team has developed a photometry device to the Brazilian market to determine the concentration of ethanol based on complexation reactions between ethanol and cerium (IV), which generate deep orange-red color on solutions. The device presents a water limit detection of 0.22% v/v in ethanol and its measurements on real samples are very accurate when compared to determinations done by Karl Fischer titration at 95% confidence level for the same samples. The components and assembled version of the device can be seen at Figure 3.

Additional information on the latest studies of LMF team in this topic can be accessed at:

Giordano, G. F.; Ferreira, D. C. M.; De Carvalho, T. R.; Vieira, L. C. S.; Piazzetta, M. H. O.; Lima, R. S.; Gobbi, A. L. Portable platform for rapid and indirect photometric determination of water in ethanol fuel samples, Analytical Methods, v. 6, p. 9497, 2014.

Lima, R. S.; Piazzetta, M. H. O.; Gobbi, A. L.; Segato, T. P.; Cabral, M. F.; Machado, S. A. S.; Carrilho, E. Highly sensitive contactless conductivity microchips based on concentric electrodes for flow analysis, Chemical Communications, v. 49, p. 11382, 2013.

Figure 3. Home-made photometry system. Components of the developed platform (a) and the assembled device (b). 1, blue LED (light source); 2, sample reservoir (reaction zone); and 3, photodiode (detector). These three parts are vertically aligned. Electronics was made according to paper reported by Ellerbee et al. (Analytical Chemistry, 2009, 81, 8447). Features not drawn to scale.