Flexible organic TFT bio-signal amplifier using reliable chip component assembly process with conductive adhesive

Abstract

This paper presents a flexible organic thin-film transistor (OTFT) amplifier for bio-signal monitoring and presents the chip component assembly process. Using a conductive adhesive and a chip mounter, the chip components are mounted on a flexible film substrate, which has OTFT circuits. This study first investigates the assembly technique reliability for chip components on the flexible substrate. This study also specifically examines heart pulse wave monitoring conducted using the proposed flexible amplifier circuit and a flexible piezoelectric film. We connected the amplifier to a bluetooth device for a wearable device demonstration.

9‐2: Invited Paper: Stretchable Electronics for Wearable Microvolt Biosignal Monitoring Systems

“…A waterproof hybrid encapsulation stack comprising a 200-nm-thick Au layer sandwiched between a 100-nm-and 1.2-µm-thick parylene layer was deposited on the transistors to serve as a passivation layer against oxygen diffusion, humidity, and mechanical attrition in vivo as well as an overcoat layer to enhance mechanical flexibility and durability, because the organic semiconducting layer was located at the neutral strain position [10], reducing the effective strain at the TFT plane. All the detailed process can be seen in our previous work [11]. The amplifier is based on a pseudo-CMOS inverter that is known to achieve high-gain (greater than 50 times) amplification [8].…”

“…AC gain is defined as the peak-to-peak amplitude ratio of the output and input waveforms. (b) Adapted from [11]. Copyright 2017, IEEE.…”

“…(b) Circuit diagram of the amplification circuit consisting of pseudo-CMOS architecture (four p-type TFTs: P 1 , P 2 , P 3 , P 4 ), input capacitor C 0 , and feedback resistance R 0 . Adapted from[11]. Copyright 2017, IEEE.…”

56‐3: Student Paper: An Amplifier with Higher Gain Using Corbino—TFTs

“…However, in order for the amplifier to be implanted in the body, it must be placed on a flexible substrate. For getting the bio signals, there are many efforts to implement circuit on flexible substrate [3]- [4]. And due to the surge in medical costs due to the increase in the elderly population, medical services using remote medical treatment and smart devices are rapidly spreading as an alternative.…”