Nuria López Ruiz

Associate Professor

Research

There is a growing interest in the research and use of portable and handheld instrumentation in the lastest years. They have the important characteristic of being able to move the laboratory to the sample and not vice versa with the main aim of monitoring and analysing potential hazardous samples and explosive atmospheres where real-time data and remote monitoring are mandatory in order to enable rapid decision-making.

Optical chemical sensors

My initial research was focused on the colorimetric detection of optical chemical sensors that change their optical properties with regard to the change in the environmental conditions or the change in aqueous solutions properties. My PhD was then related with colorimetry, optical chemical sensors and design and development of electronic portable prototypes.

Regarding the optical chemical sensors, I have collaborated with the Department of Analytical Chemistry of University of Granada, which develops colorimetric sensors for the study of pH, nitrites, heavy metals, oxygen, and other analytes of interest in environmental and health fields.


  • For pH determination (range 0-14) in aqueous solutions using an optical sensor array with 12 different sensing membranes. In this case, a OLED display is used as light source and twelve digital colours detectors are used to determine the colour information of the membranes.



  • For measurement of gaseous oxygen concentration quantifying the intensity of luminescence emitted by a sensing membrane of PtOEP when it is optically excited. In this case, the luminescence is measured by the red coordinate provided by the digital colour detector, which changes regarding the ambiental oxygen concentration.In this case, the sensing module is placed in a RFID tag printed on flexible sustrate for being used in smart packaging.









  • For measurement of oxygen concentration using a PtOEP sensing membrane and using the red coordinate to quantify the intensity of luminescence emitted when it is optically excited. In this case, an external ultraviolet LED is needed as excitation source.



  • For determination of pH and nitrite concentration using a developed paper-based microfluidic device. Using a stamp and indelibre ink over filter paper, it is possible to create channels to lead the sample to the sensing areas where the reagents are placed to initiate the colorimetric reactions.



  • This is a full-passive flexible multigas sensing tag for the determination of oxygen, carbon dioxide, ammonia, and relative humidity readable by a smartphone. This tag is based on near field communication (NFC) technology for energy harvesting and data transmission to a smartphone.


    • Ballistocardiographic analysis

    Ballistocardiography (BCG) is a technique for evaluating the cardiac function of a patient. In the last decade, the research and use of BCG have gained renewed attention due to the development of new sensors and computational techniques, which have led to more accurate results. The main advantage of this technique is that is a non-invasive and comfortable procedure for the patient that helps reduce the stress caused by other medical equipment, such as an electrocardiograph, while sleeping.

    We have developed several systems using different sensors for this purpose, combining BCG with smartphone Android applications and machine learning to improve previous results published in the literature.


  • The proposed system registers the heart rate, breathing rate and movement information of a lying patient reducing the complexity of the usual acquisition electronics by making use of a commercial digital optical. This device registers variations in the intensity of light reaching its sensing surface that are produced by vibrations of the bed mattress. The output of the detector is directly transmitted as digital words, and therefore, only digital processing is required to obtain the parameters of interest.

    • Microfluidic platforms

    In this case, we have used several smartphones as analytical instruments using their built-in cameras as colour detector. Three different Android applications have been developed in order to extract the colorimetric information of different optical sensors and samples.


  • Here we present a fast and cheap prototyping technique for the realisation of paper-based microfluidic devices simply by using a stamp and indelible ink. The proposed mechanism involves contact stamping of indelible ink to laboratory filter paper using a PDMS stamp, which defines the microfluidic structure.





  • A detection system has been integrated in the new chip, consisting of a white light-emitting diode as a light source and a high-resolution digital colour sensor as the detector, which are able to detect changes in colour produced by the reaction of the sensing chemistry and carbon dioxide in water.