SU-8 cantilever with integrated pyrolyzed glass-like carbon piezoresistor

Abstract

Glass-like carbon (GC) is a nongraphitizing material composed entirely of carbon atoms produced from selected organic polymer resins by controlled pyrolysis in an inert atmosphere. The GC properties are a combination of the properties of glass, ceramic, and graphite, including hardness, low density, low thermal conductivity, high chemical inertness, biocompatibility, high electrical conductivity, and microfabrication process compatibility. Despite these unique properties, the application of GC in mechanical sensors has not been explored thus far. Here, we investigate the electrical, structural, and chemical properties of GC thin films derived from epoxy-based negative photoresist SU-8 pyrolyzed from 700 to 900 °C. In addition, we fabricated microGC piezoresistors pyrolyzed at 700 and 900 °C and integrated them into nonpyrolyzed SU-8 cantilevers to create microelectromechanical systems (MEMS) mechanical sensors. The sensitivities of the GC sensor to strain, force, surface stress, and acceleration are characterized to demonstrate their potential and limits for electromechanical microdevices.

All‐Printed Finger‐Inspired Tactile Sensor Array for Microscale Texture Detection and 3D Reconstruction

“…The fundamental aspect of tactile detection is its sensitivity to diverse mechanical stimuli from the surroundings, such as pressure, bending, tapping, slipping, and vibration. Tactile sensors have been developed to convert mechanical stimuli into electrical signals by employing different physical transduction mechanisms, including piezoresistivity, [ 33 , 34 , 35 , 36 ] capacitance, [ 37 , 38 , 39 , 40 ] piezoelectricity, [ 41 , 42 , 43 , 44 ] triboelectricity, [ 45 , 46 , 47 , 48 ] acoustics, [ 49 , 50 , 51 ] optics, [ 52 , 53 , 54 ] and magnetism. [ 55 , 56 , 57 ] Because the sensitivity of a tactile sensor is pivotal for accurate texture detection, researchers have sought to enhance it by designing various microstructures, such as pillars, [ 58 , 59 , 60 , 61 ] pyramids, [ 62 , 63 , 64 , 65 ] and hemispheres.…”

Multimodal MEMS vibration energy harvester with cascaded flexible and silicon beams for ultralow frequency response

“…A critical integration challenge is the incompatible fabrication of soft materials with silicon micromachining processes. Despite efforts such as fabricating resonators using SU-8 photoresist 26 , 27 , Young’s modulus of SU-8 is still too high to decrease the resonant frequency to the ideal low level for MEMS energy harvesters. Therefore, the compatible fabrication of soft materials on wafers is still a significant challenge.…”

Multimodal MEMS vibration energy harvester with cascaded flexible and silicon beams for ultra-low frequency response

“…The critical challenge here is the incompatible fabrication of soft materials with the silicon micromachining process. Despite efforts like fabricating resonators using SU-8 photoresist 26,27 , the Young's modulus of SU-8 is still too high to decrease resonant frequency to the ideal Hertz level for MEMS energy harvesters. Therefore, the compatible fabrication of soft materials on wafer is still a grave challenge.…”