Fabrication of Two-Dimensional and Three-Dimensional High-Resolution Binder-Free Graphene Circuits Using a Microfluidic Approach for Sensor Applications

Abstract

In this study, a simple microfluidic method, which can be universally applied to different rigid or flexible substrates, was developed to fabricate high-resolution, conductive, 2D and 3D microstructured graphenebased electronic circuits. The method involves controlled and selective filling of microchannels on substrate surfaces with a conductive binder-free graphene nanoplatelets (GNP) solution. The ethanolthermal reaction of GNP solution at low temperatures (~75 °C) prior to microchannel filling (pre-heating) further reduces GNP, enhances conductivity, reduces sheet resistance (~0.05 kΩ sq-1), enables room temperature fabrication and eliminates harsh post-processing, which makes this fabrication technique compatible with degradable substrates. This method can also be used in combination with 3D printing to fabricate 3D circuits. The feature sizes of the graphene patterns can range from a few micrometers (down to ~15 µm in width and ~5 µm in depth) to a few millimeters and use very small amounts of GNP solution (~2.5 mg of graphene to obtain ~0.1 kΩ sq-1 of sheet resistance for 1 cm2). This microfluidic approach can also be implemented using other conductive liquids, such as conductive graphene-silver solutions. This technology has the potential to pave the way for low-cost, disposable and biodegradable circuits for a range of electronic applications including near field communication antennas, pressure or strain sensors.

Design of 3D Controller Using Nanocracking Structure-Based Stretchable Strain Sensor

“…Three-dimensional motion sensing techniques can be broadly classified into two primary categories: contact and non-contact methods. The contact approach involves the use of stretchable or wearable devices embedded with an array of sensors, such as inertial, skin conductivity, and sound pressure sensors [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. In contrast, the non-contact method utilizes optical, ultrasonic, infrared [ 14 ], or magnetic fields [ 24 , 25 , 26 , 27 , 28 ] for motion detection.…”

Corona-Enabled Electrostatic Printing for Ultra-fast Manufacturing of Binder-Free Multifunctional E-Skins

“…29 Thus, it is highly desirable to eliminate or reduce the use of passive polymer binders during the printing process. 30 This work is reporting an innovative new printing technique, corona-enabled electrostatic printing (CEP), to overcome the above limitations. In CEP, the to-be-printed substrate is placed in between the material and corona discharge (CD) in a contactless way.…”

“…However, the usage of binders introduces many limitations, including (1) curing/drying of polymer additives often takes long time and high temperatures, leading to increased manufacturing cost and limited material options; (2) low melting/softening temperature of polymer additives limits the high-temperature applications of PSEs; and (3) insulation and encapsulation of passive materials may compromise the sensitivity of nanomaterial networks . Thus, it is highly desirable to eliminate or reduce the use of passive polymer binders during the printing process …”