**4.3 Fabrication of wearable 3D electromechanical sensor**

For the wearable 3D electromechanical sensor, the substrate and sensing materials are combined into 3D structure. The first method introduced is microscale modeling. It is often utilized to fabricate different microstructures in substrates, electrodes, and sensing composites. Successfully designed microstructure not only can be used to increase the sensitivity of piezoresistive but also that of capacitive sensors when microstructured dielectric is applied. Different modules have been developed, including micromachined wafers, silk fabrics, and even plant leaves. During the fabrication process, sensing materials are simply poured onto the module and peeled off after partial or complete drying. The adhesion between processed

**89**

**Figure 5.**

and 1.2 mm in height [67].

*Wearable Electromechanical Sensors and Its Applications DOI: http://dx.doi.org/10.5772/intechopen.85098*

material and module is the most important parameters for this technique, which can

3D printing is the best candidate for developing 3D constructions and has gained great popularity due to its powerful ability [66]. If the sensing materials are well prepared, arbitrary structures can be printed with 3D printing with adjustable resolution, even lower than 0.1 μm. For instance, A three-layer sensor has been fabricated in a single step by 3D printing, which originally requires multiple steps by using traditional method, including micromolding, laminating, and infilling. Wearable pressure sensor has also been realized by a multimaterial, multiscale, and multifunctional 3D printing approach. The size of this sensor is 3 × 3 mm in area

be adjusted by necessary pretreatment and sophisticated geometric design.

*Health motion monitoring with CNT-based strain sensor: (a) impact pressure, (b) muscle movement, (c) heartbeat, (d) finger motion, (e) finger touch, (f) schematic diagram of sensor array, (g) magnified view of the sensor array, (h) optical photograph of a fabricated sensor array containing 25 × 25 pixels, (i) circuit schematic of the sensor matrix (j–n) foot pressure pattern, and (o) strain sensor attached on the human right foot.*

*Wearable Electromechanical Sensors and Its Applications DOI: http://dx.doi.org/10.5772/intechopen.85098*

*Wearable Devices - The Big Wave of Innovation*

another special method to fabricate fiber shape wearable electromechanical sensor. **Figure 5c** shows a fiber strain sensor fabricated with coaxial wet-spinning and posttreatment process. The spinning nozzle has the coaxial inner and outer channels, respectively. The inner spinning dope is SWCNT/CH3SO3H, and the outer spinning solution is the solution of thermoplastic elastomer (TPE) in CH2Cl2. The SWCNT/ CH3SO3H dope from the inner channel and the TPE/CH2Cl2 solution from the outer channel are introduced into the ethanol coagulation bath simultaneously. A single TPE-wrapped SWCNT coaxial fiber is then wetspun and collected successfully. The sensors attain high sensitivity (with a gauge factor of 425 at 100% strain), high

*Wearable electromechanical sensor fabricated with different techniques: (a) inkjet printing,* 

For the wearable 3D electromechanical sensor, the substrate and sensing materials are combined into 3D structure. The first method introduced is microscale modeling. It is often utilized to fabricate different microstructures in substrates, electrodes, and sensing composites. Successfully designed microstructure not only can be used to increase the sensitivity of piezoresistive but also that of capacitive sensors when microstructured dielectric is applied. Different modules have been developed, including micromachined wafers, silk fabrics, and even plant leaves. During the fabrication process, sensing materials are simply poured onto the module and peeled off after partial or complete drying. The adhesion between processed

**88**

**Figure 4.**

stretchability, and high linearity.

*(b) dropping casting, and (c) spray coating.*

**4.3 Fabrication of wearable 3D electromechanical sensor**

#### **Figure 5.**

*Health motion monitoring with CNT-based strain sensor: (a) impact pressure, (b) muscle movement, (c) heartbeat, (d) finger motion, (e) finger touch, (f) schematic diagram of sensor array, (g) magnified view of the sensor array, (h) optical photograph of a fabricated sensor array containing 25 × 25 pixels, (i) circuit schematic of the sensor matrix (j–n) foot pressure pattern, and (o) strain sensor attached on the human right foot.*

material and module is the most important parameters for this technique, which can be adjusted by necessary pretreatment and sophisticated geometric design.

3D printing is the best candidate for developing 3D constructions and has gained great popularity due to its powerful ability [66]. If the sensing materials are well prepared, arbitrary structures can be printed with 3D printing with adjustable resolution, even lower than 0.1 μm. For instance, A three-layer sensor has been fabricated in a single step by 3D printing, which originally requires multiple steps by using traditional method, including micromolding, laminating, and infilling. Wearable pressure sensor has also been realized by a multimaterial, multiscale, and multifunctional 3D printing approach. The size of this sensor is 3 × 3 mm in area and 1.2 mm in height [67].
