• Journal of Sensor Science and Technology
• /
• v.32 no.6
• /
• pp.386-390
• /
• 2023

Stiffness-engineered stretchable substrate technology has been widely used to produce stretchable displays, transistors, and integrated circuits because it is compatible with various flexible electronics technologies. However, the stiffness-engineering technology has never been applied to transistor-based stretchable strain sensors. In this study, we developed thin-film transistor-based strain sensors on stiffness-engineered stretchable substrates. We designed and fabricated strain-sensitive stretchable resistors capable of inducing changes in drain currents of transistors when subjected to stretching forces. The resistors and source electrodes of the transistors were connected in series to integrate the developed stretchable resistors with thin-film transistors on stretchable substrates by printing the resistors after fabricating transistors. The thin-film transistor-based stretchable strain sensors demonstrate feasibility as strain sensors operating under strains of 0%-5%. This strain range can be extended with further investigations. The proposed stiffness-engineering approach will expand the potential for the advancement and manufacturing of innovative stretchable strain sensors.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2010.05a
• /
• pp.707-708
• /
• 2010

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.66 no.4
• /
• pp.721-726
• /
• 2017

We fabricated stretchable thin-film transistors(TFTs) on a polydimethylsiloxane substrate with patterned polyimide island structures by using an amorphous InGaZnO semiconductor and parylene gate insulator. The TFTs exhibited a field- effect mobility of $5cm^2V^{-1}s^{-1}$ and a current on/off ratio of $10^5$ at a relatively low operating voltage. Furthermore, the fabricated transistors showed no noticeable changes in their electrical performance for large strains of up to 50 %.

• Advanced Industrial SCIence
• /
• v.1 no.1
• /
• pp.16-22
• /
• 2022

Starting with cathode ray tubes, displays are forming markets in the order of active marix organic light emitting diode (AMOLED) after PDP (Plasma Display Panel) and LCD (Liquid Crystal Display). OLED is recognized as a key field for the development of each country preparing for the fourth industrial revolution, and especially Samsung Display and LG Display, which are the top industries in Korea, are leading the market with more than 90% of OLED shares. Currently, AMOLED has moved to the area that can be folded or bent. This technology is possible because TFT (Thin Film Transistor) and OLED may be formed on a flexible substrate. In the future, the technology will move to stretchable displays, and for this, the development of substrate materials is first, and then TFT and OLED devices should also be implemented with stretchable materials.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.389.2-389.2
• /
• 2014

Polydimethylsiloxane (PDMS) based electronic devices are widely used for various applications in large area electronics, biomedical wearable interfaces and implantable circuitry where flexibility and/or stretchability are required. A few fabrication methods of electronic devices directly on PDMS substrate have been reported. However, it is well known that micro-cracks appear in the metal layer and in the lithography pattern on a PDMS substrate. To solve the above problems, a few studies for fabrication of stiff platform on PDMS substrate have been reported. Thin-film islands of a stiff region are fabricated on an elastomeric substrate, and electronic devices are fabricated on these stiff islands. When the substrate is stretched, the deformation is mainly accommodated by the substrate, and the stiff islands and electronic devices experience relatively small strains. Here, we report a new method to achieve stiff islands structures on an elastomeric substrate at a various thickness, as the platform for stretchable electronic devices. The stiff islands were defined by conventional photolithography on a stress-free elastomeric substrate. This technique can provide a practical strategy for realizing large-area stretchable electronic circuits, for various applications such as stretchable display or wearable electronic systems.

• Korean Journal of Materials Research
• /
• v.21 no.3
• /
• pp.133-137
• /
• 2011

Gold have been used as an electrode materials having a good mechanical flexibility as well as electrical conductivity, however the stretchability of the gold on a flexible substrate is poor because of its small elastic modulus. To overcome this mechanical inferiority, the reinforcing gold is necessary for the stretchable electronics. Among the reinforcing materials having a large elastic modulus, carbon nanotube (CNT) is the best candidate due to its good electrical conductivity and nanoscale diameter. Therefore, similarly to ferroconcrete technology, here we demonstrated gold electrodes mechanically reinforced by inserting fabrics of CNTs into their bodies. Flexibility and stretchability of the electrodes were determined for various densities of CNT fabrics. The roles of CNTs in resisting electrical disconnection of gold electrodes from the mechanical stress were confirmed using field emission scanning electron microscope and optical microscope. The best mechanical stability was achieved at a density of CNT fabrics manufactured by 1.5 ml spraying. The concept of the mechanical reinforced metal electrode by CNT is the first trial for the high stretchable conductive materials, and can be applied as electrodes materials in various flexible and stretchable electronic devices such as transistor, diode, sensor and solar cell and so on.

• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.1559-1560
• /
• 2015

신축성 및 웨어러블 전자소자 응용을 위하여 엘라스토머 기판 상에 박막 트랜지스터를 제작하여 그 전기적 특성을 확인하였다. 제작된 트랜지스터의 신축성 향상을 위하여 엘라스토머 기판 상에 일반적인 포토리소그래피 공정과 습식식각 공정을 이용하여 국부적 단단한 폴리이미드 영역을 형성하여 사용하였다. 트랜지스터 특성 확인 결과 약 30 % 이상의 신축에서도 정상적인 트랜지스터 동작이 가능함을 확인하였다.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2012.05a
• /
• pp.69.3-69.3
• /
• 2012

A high-performance low-voltage graphene field-effect transistor (FED array was fabricated on a flexible polymer substrate using solution-processable, high-capacitance ion gel gate dielectrics. The high capacitance of the ion gel, which originated from the formation of an electric double layer under the application of a gate voltage, yielded a high on-current and low voltage operation below 3 V. The graphene FETs fabricated on the plastic substrates showed a hole and electron mobility of 203 and 91 $cm^2/Vs$, respectively, at a drain bias of - I V. Moreover, ion gel gated graphene FETs on the plastic substrates exhibited remarkably good mechanical flexibility. This method represents a significant step in the application of graphene to flexible and stretchable electronics.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.08a
• /
• pp.67-67
• /
• 2012

Graphene, two-dimensional one-atom-thick planar sheet of carbon atoms densely packed in a honeycomb crystal lattice, exhibits fascinating electrical properties, such as a linear energy dispersion relation and high mobility in addition to a wide-range optical absorption and high thermal conductivity. Graphene's outstanding tensile strength allows graphene-based electronic and photonic devices to be flexible, bendable, or even stretchable. Recently many groups have reported high performance electronic and optoelectronic devices based on graphene materials, i.e. field-effect transistors, gas sensors, nonvolatile memory devices, and plasmonic waveguides, in which versatile properties of graphene materials have been incorporated into a flexible electronic or optoelectronic platform. However, there are several fundamental or technological hurdles to be overcome in real applications of graphene in electronics and optoelectronics. In this tutorial we will present a short introduction to the basic material properties and recent progresses in applications of graphene to electronics and optoelectronics and discuss future outlook of graphene-based devices.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.67 no.6
• /
• pp.799-803
• /
• 2018

We demonstrated memory thin-film transistors (MTFTs) with organic ferroelectric polymer poly(vinylidene fluoride-co-trifluoroethylene) and an amorphous oxide semiconducting indium gallium zinc oxide channel on the elastomeric substrate. The dielectric constant for the P(VDF-TrFE) thin film prepared on the elastomeric substrate was calculated to be 10 at a high frequency of 1 MHz. The voltage-dependent capacitance variations showed typical butterfly-shaped hysteresis behaviors owing to the polarization reversal in the film. The carrier mobility and memory on/off ratio of the MTFTs showed $15cm^2V^{-1}s^{-1}$ and $10^6$, respectively. This result indicates that the P(VDF-TrFE) film prepared on the elastomeric substrate exhibits ferroelectric natures. The fabricated MTFTs exhibited sufficiently encouraging device characteristics even on the elastomeric substrate to realize mechanically stretchable nonvolatile memory devices.