2016-12-23T18:49:38

Antibody-immobilized AlGaN/GaN high electron mobility transistors (HEMTs) were used to detect a short peptide consisting of 20 amino acids. One-binding-site model and two-binding-site model were used for the analysis of the electrical signals, revealing the number of binding sites on an antibody and the dissociation constants between the antibody and the short peptide. In the binding-site models, the surface coverage ratio of the short peptide on the sensor surface is relevant to the electrical signals resulted from the peptide-antibody binding on the HEMTs. Two binding sites on an antibody were observed and two dissociation constants, 4.404×10(-11) M and 1.596×10(-9) M, were extracted from the binding-site model through the analysis of the surface coverage ratio of the short peptide on the sensor surface. We have also shown that the conventional method to extract the dissociation constant from the linear regression of curve-fitting with Langmuir isotherm equation may lead to an incorrect information if the receptor has more than one binding site for the ligand. The limit of detection (LOD) of the sensor observed in the experimental result (~10 pM of the short peptide) is very close to the LOD (around 2.7-3.4 pM) predicted from the value of the smallest dissociation constants. The sensitivity of the sensor is not only dependent on the transistors, but also highly relies on the affinity of the ligand-receptor pair. The results demonstrate that the AlGaN/GaN HEMTs cannot only be used for biosensors, but also for the biological affinity study.

Enhanced stability, lifetime and safety of high power IGBT (Insulated Gate Bipolar Transistor) modules are a result of their progressive material selection, thereby necessitating the invention of new composite materials. High-end power modules are operated close to the maximum physical matching capability of their layered materials, leading to decreased lifetime and degraded performance, and thus creating demand for new composite materials with higher thermal conductivity and lower coefficient of thermal expansion (CTE). To eliminate failures caused by the CTE mismatch (³300%) between metal and substrate material interface, we report for the first time Cu/GrCu composite which exhibits similar thermal conductivity to pure copper (390 W/(m•K)), much higher than the range of metal injection molded copper heat sink (320 340 W/(m•K)), while featuring low silicon-like CTE (³5 ppm/K). This is realized by injection parameter manipulation to not only reduce voids (vacancies) but increase the interface bonding through the use of electrodeposited copper on graphene (i.e., GrCu). Such excellent property locates the Cu/GrCu in the top of the Ashby map and shows excellent temperature stability with lower thermal distortion parameter (TDP). Thus, this excellent composite material is the only material simultaneously with high thermal conductivity and low CTE, making it uniquely suited for high power module applications, especially for hybrid and electric vehicles.

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