#  Fabrication 

 



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####  **The fabrication of the soft bending actuator with magnetic curvature sensor**

 The steps of fabrication can be summarized as follows:

 Step 1: Two inner bodies (i.e., linear muscles) of the module are fabricated first using a three-dimensional (3D) printed mold and silicone rubber (Smooth-On Ecoflex 0030) (Figure.5).

   ![Step1-soft actuator](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/srtsandbox/files/soft_actuator_fabrication-step1.jpg?itok=kuB8oj4c) 

 

Figure.5 Step1 Step 2: Inextensible sewing thread is wrapped and bonded around each linear muscle (Figure.6).

   ![Step2-Soft actuator](/sites/g/files/omnuum4601/files/styles/hwp_1_1__360x360_scale/public/srtsandbox/files/soft_actuator_fabrication-step2.jpg?itok=YqWeXJu4) 

 

Figure.6 Step2 Step 3: With the flexible curvature sensor in the middle, two pieces of self-adhesive laminate sheet are laser cut and attached together to form the constraint layer (Figure.7).

   ![Step3-soft actuator](/sites/g/files/omnuum4601/files/styles/hwp_1_1__960x960_scale/public/srtsandbox/files/soft_actuator_fabrication-step3.jpg?itok=-f7y8Ob5) 

 

Figure.7 Step3    ![Laminating sheet](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/srtsandbox/files/laminating_sheet.jpg?itok=W9IsAaKl) 

 

Figure.8 Laminating sheet Step 4: The constraint layer and two inner bodies are placed in a second 3D printed mold and filled with silicone rubber (Figure.9).

   ![Step4-soft actuator](/sites/g/files/omnuum4601/files/styles/hwp_1_1__960x960_scale/public/srtsandbox/files/soft_actuator_fabrication-step4.jpg?itok=VmzeUPEE) 

 

Figure.9 Step4 Step 5: Acrylic end-connector caps and vent screws are attached to both ends of the body (Figure.10).

 ![Step5-Soft actuator](/sites/g/files/omnuum4601/files/srtsandbox/files/soft_actuator_fabrication-step5.jpg)

 

Figure.10 Step5####  **The fabrication of the magnetic curvature sensor:**

 The entire fabrication process consists of three steps as below.

 Step 1 : Circuit traces are designed and printed on a copper-clad flexible substrate (Pyralux, 3M, Figure.11(a)) using a solid ink printer (Xerox Color 8570, Figure.11(b)).

   ![Printerand sheet](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/srtsandbox/files/printer.png?itok=bIcopLY0) 

 

Figure.11 (a) Flex PCB Material - Pyralux (b) ColorQube 8570, Color Printers: Xerox. Step 2: The patterned copper-clad substrate is placed in a ferric chloride (Figure.12(a)) etching tank (Figure.12(b)) that remove all exposed copper, leaving the electrical traces intact. Usually take around 15 min.

   ![Ferric and etching](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/srtsandbox/files/ferric.png?itok=MAI7aifc) 

 

Figure.12 (a) Ferric chloride copper etchant solution. (b) Etching tank Step 3: Discrete circuit components (AH49E) are soldered and the miniature magnet is mounted on its precise position using a microscope.