Electrochemical Sensors

Electrochemical sensors are molecular sensing devices that intimately couple a biological recognition element to an electrode transducer. Such devices produce an accurate, sensitive, simple, inexpensive, compact, and low-power platform for point-of-care diagnosis. The most common example is a glucose sensor, in this system glucose oxidase is immobilized in the working electrode of an electrochemical cell (3 electrode system) and the current from the oxidation-reduction reaction is detected through cyclic voltammetry, differential pulse voltammetry, amperometry, and various other electrical methods. Our lab focuses on electrochemical measurements for the multiple detections of different biomarkers for specific diagnoses, such as Sepsis. Also, a study focused on Recombinase Polymerase Amplification (RPA) assay, an isothermal DNA amplification technology, combined with electrochemical techniques to investigate the presence of viruses in the human samples was developed before. Currently, we are working in collaboration with other research groups to develop a diagnostic device for a new Parkinson's disease biomarker. With different substrates, electrodes, nanomaterials, and fabrication techniques, we can optimize the sensitivity and selectivity of the sensing platforms. 

•  
• Electrochemical biosensor combined with recombinase polymerase amplification (RPA). The RPA reaction occurs on the working electrodes, and amplicon detection is quantified by differential pulse voltammetry (DPV). (Read More)

• (a) Flexible and Printed PET-based sensor (WE/CE: Ti/Au and RE: Ag) with an active layer surface composed of the nanocomposite and the immobilized bioreceptor. (b) The variation of the peak currents with the DPV responses (inset graphs) for various concentrations of PCT in the human plasma.

GFET Biosensors

Graphene is one of the most promising biocompatible nanomaterials for point-of-care biomedical applications, such as immunosensor and DNA sensors. In our lab, we developed a graphene-based solution-gated field-effect transistor (GFET) with a unique structure for Tp53 DNA sensing. With a structure where the electrolyte is a common path between the active layer (graphene) and the gate terminal in an array sensor. We investigate the interaction between the carrier charges of the biological fluid and the non-functionalized graphene layer. Another GFET device developed by our group focuses on the measurement of the changes in the electrical charges of human whole blood during the coagulation process. The inserted blood sample works as a common path, through a microchannel containing thromboplastin reagent (tissue factor), between the active layer (graphene) and the gate terminal. This device can be used to detect the prothrombin time by working as a point-of-care test.

•  
• Electrical performance of solution-gated GFET. (a) Transfer curve of GFET before and (b) after the V_Dirac shifts in different concentrations of complementary, one-mismatch, and noncomplementary DNA. (Read More)

• GFET sensor to monitor the electrical properties of the hemostasis process. (a) Measurement setup using a semiconductor parameter analyzer. (b) Comparison between HWB sample (initial transfer curve, at 0 min) and PBS solution based on normalized transfer curves from a single device. (Read More)

► For more information: Hyo Eun Kim (hyoeunonon@gmail.com); Ariadna Schuck (arischuck@g.skku.edu)