Flexible Inkjet-Printed Heaters Utilizing Graphene-Based Inks

Abstract

Thermal sensors are mainly based on the selective heating of specific areas, which in most cases is a critical feature for both the operation and the performance of the thermal device. In this work, we evaluate the thermoelectrical response of two graphitic materials, namely (a) a commercial 2.4%wt graphene–ethyl cellulose dispersion in cycloxehanone and terpineol (G) and (b) a custom functionalized reduced graphene oxide (f-rGO) ink in the range of −40 to 100 °C. Both inks were printed on a flexible polyimide substrate and the Thermal Coefficients of Resistance (TCR) were extracted as TCRG = −1.05 × 10−3 °C−1 (R2 = 0.9938) and TCRf-rGO = −3.86 × 10−3 °C−1 (R2 = 0.9967). Afterward, the inkjet-printed devices were evaluated as microheaters, in order to exploit their advantage for cost-effective production with minimal material waste. f-rGO and G printed heaters reached a maximum temperature of 97.5 °C at 242 mW and 89.9 °C at 314 mW, respectively, applied by a constant current source and monitored by an infrared camera. Repeatability experiments were conducted, highlighting the high robustness in long-term use. The power–temperature behavior was extracted by self-heating experiments to demonstrate the ability of the devices to serve as heaters. Both static and dynamic evaluation were performed in order to study the device behaviors and extract the corresponding parameters. After all the experimental processes, the resistance of the samples was again evaluated and found to differ less than 13% from the initial value. In this work, fabrication via inkjet printing and demonstration of efficient and stable microheaters utilizing a custom ink (f-rGO) and a commercial graphene ink are presented. This approach is suitable for fabricating selectively heated geometries on non-planar substrate with high repeatability and endurance in heat cycles.

Graphene-Based Composites with Silver Nanowires for Electronic Applications

“…Flexible printed electronics (FPEs) are expected to dominate soon in the field of electronics because they have shown great potential in a wide range of applications [1] including sensors and microheaters [2,3], transistors [4], light-emitting diodes (LEDs) and organic LEDs (OLEDs) [5,6], solar cells [7], and wearable electronics and e-textiles [8,9]. FPE development requires the connection of flexible conductive structures, interfaces, and contacts, which can be created through the printing of conductive, semiconductive, and dielectric nanomaterials on suitable substrates.…”

“…However, apart from the major disadvantage of a high cost, silver-based conductive inks require high sintering temperatures and thus their use on temperature sensitive substrates such as paper and polyethylene terephthalate (PET) remains a challenge [20]. On the other hand, conductive carbon-based nanomaterials such as graphene and graphene derivatives are also promising materials for printed electronics due to their interesting properties such as high mechanical durability and flexibility, high inherent current mobility, and chemical corrosion resistance [3,21].…”

Design and Thermal Analysis of Flexible Microheaters

“… Structures of microheaters based on graphene fabricated with ( a ) inkjet-printed method [ 21 ], ( b ) laser-induced method [ 22 ], and ( c ) ultrafast laser ablation method [ 23 ]. Reprinted with permission from MDPI, ACS, and ELSEVIER.…”

“…Recently, with the development of flexible electronics, low power consumption and fast response microheater are desired in many areas [ 6 , 19 ]. Because of the unique electrical and thermal conductivity, the graphene-based electrothermal heater has shown the properties of fast response, flexibility, and high-efficiency energy conversion [ 20 , 21 , 22 , 23 ]. Graphene-based typical structures fabricated with different methods are shown in Figure 1 .…”

Study of Single and Multipass f–rGO Inkjet-Printed Structures with Various Concentrations: Electrical and Thermal Evaluation

“…[ 5 , 6 , 7 ], with low material consumption and almost zero waste [ 8 ]. It is effective for the fabrication of a variety of complex electronic components and devices such as: sensors (gas [ 9 , 10 ], temperature [ 11 , 12 , 13 , 14 ], and humidity [ 14 , 15 ]), microheaters [ 16 , 17 , 18 ], energy harvesters, capacitors, FETs, etc. [ 19 , 20 , 21 , 22 ].…”