title: Extended-gate field-effect transistor packed in micro channel for glucose, urea and protein biomarker detection.
abstract: This study developed a packaging method to integrate the extended-gate field-effect transistor (EGFET) into a microfluidic chip as a biological sensor. In addition, we present two immobilization approaches for the bio-recognition that are appropriate to this chip, allowing it to measure the concentrations of hydrogen ions, glucose, urea, and specific proteins in a solution. Alginate-calcium microcubes were used to embed the enzymes and magnetic powder (enzyme carrier). When the sensing chip needs the enzyme for the catalytic reaction, the alginate microcubes containing the corresponding enzymes enter through the flow channel and are immobilized on the EGFET surface with an external magnet. High sensing performance of the chip is achieved, with 37.45 mV/mM for measuring hydrogen ions at pH 6-8 with a linearity of 0.9939, 7.00 mV/mM for measuring glucose with a linearity of 0.9962, and 8.01 mV/mM for measuring urea with a linearity of 0.9809. In addition, based on the principle of the immunoassay, the magnetic beads with the specific antibody were used to capture the target protein in the sample. Then, negatively charged DNA fragments bound to a secondary antibody were used to amplify the signal for EGFET measurement. The magnetic beads with completed immune response bonding were then fixed on the surface of the sensor by an external magnetic field. Therefore, the measured object can directly contact the sensor surface, and quantitative detection of the protein concentration can be achieved. Apolipoprotein A1 (APOA1) was detected as a target protein, with a minimum detection limit of approximately 12.5 ng/mL.
authors.affiliation: Department of Electronic Engineering, Chang Gung University, Taoyuan 333, Taiwan, Republic of China. yenheng@mail.cgu.edu.tw.|Graduate Institute of Medical Mechatronics, Chang Gung University, Taoyuan 333, Taiwan, Republic of China. yenheng@mail.cgu.edu.tw.
authors.forename: Yen-Heng
authors.initials: YH
authors.lastname: Lin
authors.affiliation: Department of Electronic Engineering, Chang Gung University, Taoyuan 333, Taiwan, Republic of China.
authors.forename: Chih-Pin
authors.initials: CP
authors.lastname: Chu
authors.affiliation: National Chip Implementation Center, Hsinchu, Taiwan, Republic of China.
authors.forename: Chen-Fu
authors.initials: CF
authors.lastname: Lin
authors.affiliation: National Chip Implementation Center, Hsinchu, Taiwan, Republic of China.
authors.forename: Hsin-Hao
authors.initials: HH
authors.lastname: Liao
authors.affiliation: National Chip Implementation Center, Hsinchu, Taiwan, Republic of China.
authors.forename: Hann-Huei
authors.initials: HH
authors.lastname: Tsai
authors.affiliation: National Chip Implementation Center, Hsinchu, Taiwan, Republic of China.
authors.forename: Ying-Zong
authors.initials: YZ
authors.lastname: Juang
mesh_terms: D000464:Alginates / Q000737:chemistry; D016632:Apolipoprotein A-I / Q000097:blood; D015415:Biomarkers / Q000032:analysis*; D015374:Biosensing Techniques / Q000295:instrumentation; D001786:Blood Glucose / Q000032:analysis*; D053938:DNA Fragmentation; D004867:Equipment Design; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007118:Immunoassay; D057230:Limit of Detection; D044085:Microfluidics / Q000379:methods*; D011506:Proteins / Q000032:analysis*; D014508:Urea / Q000097:blood*
chemical_list: C505693:APOA1 protein, human; D000464:Alginates; D016632:Apolipoprotein A-I; D015415:Biomarkers; D001786:Blood Glucose; D006603:Hexuronic Acids; D011506:Proteins; D020723:Glucuronic Acid; D014508:Urea
keywords: Enzyme immobilization; Extended-gate field-effect transistor; Microfluidic; Protein