A Package Technology for Miniaturized Field-Effect Transistor-Based Biosensors and the Sensor Array

Abstract

In this study, a package technology has been developed for miniaturized filed-effect transistor (FET)-based biosensors. FETs were fabricated and diced as a 1 mm × 1 mm chip. The chip was then embedded in a plastic substrate and has a coplanar surface with that of the substrate. Photolithography followed by metal deposition and lift-off process was conducted to create metal lines, which connect the FET and extend to the edge of the plastic substrate. The FET-embedded plastic substrate was then engraved by laser to form a typical micro SD card and then passivated by photoresist, leaving the source-drain channel and the gate electrode open, followed by bonding a microfluidic channel made of PMMA. The packaged FET was tested in air and in buffer solution to confirm the well electrical isolation between metal interconnects and the solution, and the successful liquid flowing in the microfluidic channel. A FET sensor array was also made by embedding 8 FET chips into one plastic substrate with the same process. This package technology can largely reduce the cost of the sensor due to the very small size of the FET chip. The sensor chips can also be arbitrarily positioned into one plastic substrate to fit with multiple microfluidic channels, leading to great flexibility in the design of the sensor array. The result has shown a promising 2D system-in-package technology for sensor applications.

A Comprehensive Model for Whole Cell Sensing and Transmembrane Potential Measurement Using FET Biosensors

“…22 To explain in brief, 1 mm 2 GaN HEMT devices are embedded in epoxy resin and cured thermally at high temperatures of 125 and 165…”

Stretchable pH sensing patch in a hybrid package

“…Furthermore, the materials for packaging have to be chemically, electrically and thermally stable. Conventional packaging often realized in microfluidic channels [4], molded blocks [9] and multi-layered lamination [7,10] is insufficient for health applications. These techniques are either difficult to be implemented in real-time electrochemical sensing due to the fully sealed structure or difficult to be stretchable due to its rigidity.…”

Zika virus detection using antibody-immobilized disposable cover glass and AlGaN/GaN high electron mobility transistors

“…16 One attractive approach is the use of AlGaN/GaN high electron mobility transistors (HEMTs) functionalized with antibody or aptamer over the active gate channel. [17][18][19][20][21][22] The AlGaN/GaN HEMTs have demonstrated superior biosensing characteristics due to a high density two-dimensional electron gas (2DEG) channel located close the surface (around 25 nm) and very sensitive to changes in surface charges. [21][22][23][24][25][26][27] bio-sensing applications with the antibody immobilized directly over the active gate channel, the detection would not be very consistent for high ionic strength solutions such as human blood or serum.…”

“…This is due to the high charge screening effect in high ionic strength solutions, where the Debye length is much shorter than the antibody. 22,24 To overcome this challenge, Hsu et al 22 and Sarangadharan et al 24 reported double pulse measurements using AlGaN/GaN HEMT biosensors, with an electrical double layer approach in which the functionalized gate electrode is spatially separated from the active gate channel area to eliminate these charge screening effects in high ionic strength solutions. This allows the measurements to be performed without any dilution or washing process.…”

“…This allows the measurements to be performed without any dilution or washing process. 22,24 In this work, a disposable cover glass externally integrated with an AlGaN/GaN HEMT was employed to detect the ZIKV. Two metal electrodes were fabricated on the glass: one of them functionalized with antibody and the other one connected to the gate side of the HEMT device.…”