Materials and MethodsTo make the strain sensor we first start with 125-µm Kapton sheet on which a layer of amorphous carbon is deposited. This process is done in a clean room which takes approximately 8 hours to do. Once the carbon Kapton is deposited, the next step is laser micromachining which is a 2 hour process to make using Alpha-Cam software. Once all sensors are made, the electrical connections are done so that the resistance across the sensor can be measured. Last each strain sensor is encapsulated in poly-dimethylsiloxane between 10 to 20%. The sensor is not kept at the joint, but instead a piece of Kapton sheet which is attached to the sensor is kept over the joint. When the finger is bent, the Kapton sheet bends. This stretches the sensor attached to the sheet and thereby gives a better sensitivity.

AcknowledgmentsWe thank Dr. Kambiz Alavi and Mohammadreza Jahangir Moghadam for heading the REU Program along with Smitha Rao and J.-C. Chiao. We also thank NSF and UTA for funding and hosting the REU program.REU Site: Research Experiences for undergraduates in Sensors and Applications at University of Texas at Arlington

Results.

Summary and Conclusions

A strain sensor integrated with a wireless system

to monitor and measure strain at any flexing region

has been demonstrated. The main focus is on

measuring the strain caused on different region of the

body like the human finger and maybe the human

stomach. Strain sensors can be used by doctors to

help measure the strain of the flexing region which

can be used to help people with arthritis for example

which affect millions of peoples. With the strain

sensors people with arthritis can get the proper help

needed to determine how much they can actually

bend their fingers with a special strain glove that will

measure the strain.

The sensor is not kept at the joint but instead a cut

out Kapton sheet which is attached to the sensor is

kept over the joint. When the finger is bent, this sheet

bends. This stretches the sensor attached to the sheet

and thereby gives a better sensitivity. The wireless

strain sensor system architecture is capable of

monitoring multiple patients and/or multiple sensors

simultaneously.

JeVaughn Julius, Obinna Igwe, Kaustubh Shinde, Smitha Rao, J.-C. ChiaoElectrical Engineering Summer REU, The University of Texas at Arlington, Arlington, Texas 76019

Literature citedTata, Uday, Hung Cao, Vaibhav Landge, Cuong M. Nguyen, and J.-C. Chiao.

"Wireless Strain Sensor Based on Amorphous Carbon for Human-Motion Detection." N.p., 20-23 Jan. 2013. Web. 22 June 2013.

"CDC - Chronic Disease - Arthritis - At A Glance." Centers for Disease Control andPrevention.N.p.,n.d.Web.28 July 2013.<http://www.cdc.gov/chronicdisease/resources/publications/aag/arthritis.htm>.

Figure 1: A encapsulated sensor in poly-dimethylsiloxane (PDMS).

Further Information

Wireless Strain Sensors

Day 5

Figure 2: The slope shows the gauge factor of the sensor of the calculated dR/R and dL/L of the plotted graph.

Day 1

Figure 5: Tested 3 sensors for sensitivity and maximum strains of Original Design (1mm width), Original Design (2mm width), and Two Triangle Design (1mm width).

Figure 4: Designs of different strain sensors for better sensitivity with different width.

Figure 3: The plotted graph show the Gauge Factor of the calculated dR/R and dL/L of one joint and three joints.

B

B D FFigure 6: Tested the repeatability of the sensors.

Contact JeVaughn Julius (juliusj@uta.edu) or Smitha Rao (smitha@uta.edu).

AbstractA wireless strain sensor system has been

designed to monitor and measure strain at any flexing region. The main focus is on measuring the strain caused on different regions of the body like the human finger and maybe the human stomach. The strain sensors are made with a laser system using 125-µm thick Kapton sheet, which is followed by an encapsulation process to package all the sensors in elastic poly-dimethylsiloxane known as PDMS which will be used to measure the strain of the flexing region.

IntroductionStrain sensors can be used to help measure the

strain of the flexing region. By measuring the strain on muscles, doctors would easily be able to detect arthritis. Arthritis effects about 50 millions U.S. adults each year and expecting to grow up to 67 millions by the year 2030. With the strain sensors people with arthritis can get the proper help needed to determine how much they can actually bend with a special strain sensor glove that will measure the strain which will helps the doctors determine what is the next proper step to take to make the patient live better.

1.5mm

1mm

0.5mm

2mm

1mm 0.5mm

dr/R vs dl/L

dr/R vs dl/L%

dr/R vs dl/L