Aerosol-jet-printed, conformable microfluidic force sensors

Abstract

Summary Force sensors that are thin, low-cost, flexible, and compatible with commercial microelectronic chips are of great interest for use in biomedical sensing, precision surgery, and robotics. By leveraging a combination of microfluidics and capacitive sensing, we develop a thin, flexible force sensor that is conformable and robust. The sensor consists of a partially filled microfluidic channel made from a deformable material, with the channel overlaying a series of interdigitated electrodes coated with a thin, insulating polymer layer. When a force is applied to the microfluidic channel reservoir, the fluid is displaced along the channel over the electrodes, thus inducing a capacitance change proportional to the applied force. The microfluidic molds themselves are made of low-cost sacrificial materials deposited via aerosol-jet printing, which is also used to print the electrode layer. We envisage a large range of industrial and biomedical applications for this force sensor.

3D Printing of Robotic Soft Grippers: Toward Smart Actuation and Sensing

“…[229][230][231] Despite being less popular than the IJP process for the fabrication of soft sensors, there have been several works on AJP printed soft sensors. [232,233]…”

Printed flexible mechanical sensors

“…Besides, the cost-effectiveness of screen printing makes the use of large area electronic or tactile skin in robotics possible. 122 While AJP 35,45,67,123 and DLP 38,40,42,43,124,125 have been applied for the fabrication of flexible mechanical sensors, they are less common due to various reasons. For example, although AJP is a newly developed printing technique with high resolution 91 and fast printing speed, 90 the cost of AJP is much higher in contrast to other techniques; while DLP can fabricate sophisticated 3D geometries with high resolution and rapid speed, the requirement of a photocurable resin limits the material selection.…”

“…10c). 35 The interdigitated microfluidic configuration effectively enhances the capacitive response similar to typical silicon-based comb-drive electrostatic sensors. Compared to a straight and parallel-electrode design, the interdigitated configuration increased the linear sensitivity of the sensor from 0.55 pF N −1 to 3.75 pF N −1 up to an applied force of 9 N, and its response remained stable for 2200+ compression cycles.…”

“…Printing technologies have also been applied to fabricate flexible force sensors using inks including silver, 35,47,48,52 CNTs, 19,34,66,122,152 liquid metals 18 and conductive polymers 114,125 as the sensing elements. Based on the sensing mechanism, they can also be grouped into three major types: capacitive, piezoelectric and others ( e.g.…”

“…Fabrication of flexible mechanical sensors by printing technologies have emerged as a versatile, economical, and enabling approach. For instance, various types of mechanical sensors (e.g., force, [33][34][35] pressure, [36][37][38][39][40] and strain [41][42][43][44][45][46] ) can be produced by leveraging many 2D/3D printing techniques including but not limited to screen printing, [47][48][49][50][51] inkjet printing, [52][53][54][55][56] direct ink writing (DIW), [57][58][59] digital light processing (DLP), [60][61][62] and fused filament fabrication (FFF). [63][64][65][66] The additive nature of printing technologies also largely reduces the fabrication cost and time; 67,68 in addition, fabrication by printing enabled the production of flexible mechanical sensors with excellent performance.…”