## 1 Introduction  
Due to their versatility and exceptional mechanical and electrical properties, nanocarbon materials have been studied for use in reinforced composites as well as in transducers [1, 2, 3]. The incorporation of nanocarbon materials, with their pertinent electrical properties, allows for applications as sensors in a wide range of fields [4, 5, 6, 7, 8, 9, 10, 11]. A nanocarbon composite can be used as a sensory material due to the electrically conductive fillers in the matrix. Having electrical conductivity, the nanocarbon composite has a piezoresistive feature that can be used like a commercial foil strain gauge. We reported the comparable strain sensing performance of a nanocarbon composite strain sensor (NCSS) to a commercial foil strain gauge [12]. Although the strain sensing performances of the two sensors are similar, the piezoresistive mechanism of the NCSS is more complicated than that of the metallic type gauge [13]. The piezoresistive mechanism of the NCSS is related to various factors, such as the properties of the matrix, the content and arrangement of the fillers, and the geometric shape of the composite. In particular, the piezoresistivity is directly related to the NCSS sensitivity, and it may be controllable via the fabrication process variables. During the sensor fabrication process, we believe that sensor irregularities generally occur due to filler randomness, including quality and dispersion, which dominate a sensor's electrical properties. Such irregularities may hamper the ability to achieve uniform performance of an individual sensor. Topredict nanoscale internal filler behavior, researchers have studied physical models [14; 15; 16; 17], computer-based molecular dynamics, and other types of simulations [18; 19; 20; 21]. Some researchers have studied variations in NCSS sensitivity based on fabrication methodology. [PERSON] et al. fabricated a single-walled carbon nanotube (SWCNT) film strain sensor using the spray method in a grid form and studied the sensor resistance and sensitivity characteristics according to the number of grids and the thickness of the sensor [22]. In addition, [PERSON] et al. fabricated a SWCNT nano strain sensor by alcohol catalytic chemical vapor deposition (ACCVD) and studied the sensor sensitivity characteristics according to the SWCNT growth time and the number of sensor grids [23]. [PERSON] et al. used the spray deposition modeling (SDM) method to fabricate carbon nanotube (CNT) sensors with varying thicknesses and investigated their piezoresistive properties [24]. [PERSON] et al. fabricated a composite sensor using carbon black and PDMS (Polydimethylsiloxane), and proposed an application case with different patterns and shapes for the sensor [25]. There have been other similar macroscopic approaches based on sensor pattern studies. [PERSON] et al. fabricated multi-walled carbon nanotube (MWCNT) film sensors using a solution/filtration method, and they tested piezoresistivity with an optimized aspect ratio to obtain a proper signal from the sensor [26]. [PERSON] and [PERSON] fabricated a MWCNT/PDMS strain sensor. They showed the correlation between the initial resistance according to sensor thickness and sensor sensitivity [27]. Other studies have investigated improvements to NCSS sensitivity by using hybrid nanocarbon composites or functionalized nanocarbon fillers [28; 29; 30]. Since the quality control of most nanocomposites remains a challenge at the mass production level, the electrical characteristics of nanocarbon composites are also hard to consistently control. Consequently, most fabricated NCSSs may not have identical piezoresistive properties in terms of the nanocomposite process at the nano or micro scales. However, a commercial strain sensor yields uniform performance according to specifications, and a customer can expect reliable output from the sensor to meet the desired purpose. Unlike conventional strain sensors, NCSSs tend to involve many complexities at micro and macro scales and, furthermore, they are difficult to fabricate.