臺大光電所所訊

Investigation of Streptavidin-Ligand Biochemical Interactions by IGZO Thin Film Transistors Integrated with Microfluidic Channels

Professor Jian-Jang Huang's laboratory

Graduate Institute of Photonics and Optoelectronics, National Taiwan University

臺灣大學光電所黃建璋教授

This is a joint research work between Prof. Y.-H. Lo from UCSD and Prof. J.-J. Huang from GIPO NTU. In this work, we demonstrate an IGZO TFT-based biosensor integrated with a microfluidic channel to monitor biochemical reactions between proteins and small molecules. The target biomaterials are applied to a Y-shaped microfluidic chamber while the reactant signal is readout by the TFT. Using Biotin-Streptavidin reaction as an example, the specific diffusion time of biotin, streptavidin, or streptavidin-biotin complex across the fluidic channel are benchmarked. By intentionally delaying the application of one specie to another, one can study properties of biochemical reactions, such as excess and exhaust conditions of the reactants, and the formation of the products while diffusing in the channel. The proposed TFT sensor provides an excellent platform in understanding the biochemical functions for the advance of biological science and drug discovery.

Ref: This work was published in “Sensors and Actuators B: Chemical. 262. 10.1016/j.snb.2018.01.177”

Figure 1. (a) The cross section of the IGZO-TFT (b) Schematic diagram of a reusable TFT biosensor. The TFT and microfluidic channel were fabricated separately and then connected together by a bond wire. The cross linkers were applied on the surface of ROI.

Figure 2. Scenarios of drain current responses when the biotin and streptavidin are applied to the fluidic channel. Using the transient response of drain currents, our system is able to detect the complete and incomplete bioreactions. The control measurement was also conducted to verify the reaction between ligands and proteins.

High-Performance Vertically-Stacked Complementary Inverter Composed of Oxide Thin-Film Transistors

Professor I-Chun Cheng

Graduate Institute of Photonics and Optoelectronics, National Taiwan University

臺灣大學光電所陳奕君教授

Complementary thin-film transistor (TFT) inverters are the fundamental building blocks for versatile thin-film logic circuits. They possess several desirable features, such as low static power consumption and high density circuit integration. Complementary inverters implemented in a vertically-stacked structure offer an additional advantage, small footprint, in comparison with their coplanar counterparts. Oxide semiconductors are promising candidate channel materials for TFT applications because they have relatively high carrier mobilities and can be processed at low temperatures. In this research, we report an on-glass high-performance vertically-stacked complementary inverter based on oxide TFTs. It is composed of a bottom-gate n-type ZnO TFT stacking on a top-gate p-type SnO TFT. Both active layers were deposited by a low-temperature rf-sputtering technique. Fig. 1 shows the transfer and output characteristics of both the ZnO and SnO TFTs. The ZnO TFT exhibits a threshold voltage of 5.1 V, field-effect mobility of 2.5 cm²/V-s, subthreshold swing of 1.8 V/decade, and on/off current ratio of 2.4х10⁷. The corresponding values for the SnO TFT are 6.2 V, 0.35 cm²/V-s, 0.9 V/decade, and 2.2х10⁴. Fig. 2 shows the static voltage transfer characteristics and gain curves of the vertically-stacked complementary oxide-TFT-based inverter with a geometric aspect ratio of 5 at supplied voltages ranging from 2 to 10 V. A high voltage gain of 56 V/V at a supply voltage of 10 V is achieved. The result demonstrates the feasibility of realizing oxide-TFT based complementary circuits with high-density integration.

Fig. 1 (a)(b) Transfer and (c)(d) output characteristics of the bottom-gate n-channel ZnO TFT and top-gate p-channel SnO TFT. The channel dimensions are W/L = 40 μm/ 20 μm.

Fig. 2 (a) Static voltage transfer characteristics and (b) gain curves of the vertically-stacked complementary TFT inverter with a geometric aspect ratio of 5 at supply voltages ranging from 2 V to 10 V.