BioElectric Generation Ariel Autrand Zaoyi Chi Diego Garcia

Bio-Electric Generation Ariel Autrand, Zaoyi Chi, Diego Garcia, Justin Havely, Qingkun Liu, Bray Moll, Andrew Mullen, and Tim O’Rourke Department of Mechanical And Electrical Engineering, Northern Arizona University; W. L. Gore and Associates, Flagstaff, AZ Abstract Simulation Modern pacemakers have a maximum life span of 10 years, due to the physical limitations of its lithium-ion battery [1]. Therefore, patients are required to undergo an invasive surgical procedure to replace the pacemaker at least every decade. This project sought to solve this problem through the development of a novel, fully implantable piezoelectric based power system. We created a prototype device that will provide power through the patient’s natural elbow movement. Through testing, we determined that our device is able to supply an output voltage and current, in an acceptable range, to operate a Medtronic Pacemaker. However, the device’s average output power of 5. 6 n. W is insufficient to maintain the pacemaker’s power draw of 10 µW. Further iterations and refinements are required to meet this requirement. A numerical simulation was computed using the parameters shown in Table 1. The simulation indicated that 1500 elbow bends per day could produce 4. 133 J, meeting the 0. 864 J requirement of a pacemaker. Manufacturing Table 1: Simulation Input Parameters Simulation Results 110 µm Size Efficiency 12 Daily Energy Required 0. 864 J Daily Energy Produced 4. 133 J Testing Procedure 12% Bends Per Day 1500 Max Bend Angle 110° Conclusions - - Figure 3: Arm Bending Apparatus Extended (Left) and Bent (Right) Figure 1: PVDF Piezoelectric Module Figure 2: Charging Circuit PCB Layout The Polyvinylidene Difluoride (PVDF) piezoelectric energy harvesting module converts the mechanical energy, developed in a user’s elbow bend, into electrical energy. Manufacturing Procedure: 1. Measure and cutout two pieces of PVDF film. 2. Use Xylene and a rag to remove the silver electrode around the border of the film. 3. Mix and apply a thin film of silver filled epoxy and mount the two layers together into a bimorph configuration. 4. Attach wire leads. 5. Encase in a protective laminate. A charging circuit was developed to regulate the energy produced by the piezoelectric device. Four matching diodes were used to rectify the signal and one diode was used to clip the voltage, should it exceed the operating voltages [2]. The signal is then fed into a super capacitor for storage. This acts as an energy buffer for when no power is generated. The signal then passes through a DCDC converter that boosts the signal to an appropriate voltage, should the device not reach the operating values. Table 3: Customer and Engineering Requirements [3, 4] Table 2: Simulation Results Simulation Parameters Thickness Specifications and Results A machine was constructed to test our piezoelectric device and was designed to simulate the natural bending motion of the human elbow using a motor. The piezoelectric device was mounted using two pieces of tape and was connected to the charging circuit. The machine was ran at a rate of 56 rpm for approximately 1 hour, with the voltage across the capacitor being measured about every 10 minutes. This process was repeated for two tests in total. Testing Results The designed device was able to meet the critical requirements, designated by the selected Medtronic Advisa DR MRI Sure. Scan A 2 DR 01 pacemaker. The operation voltage was measured as 3. 4 V and the control max current was measured as 1. 2 m. A, both being within the acceptable range. However, the device was unable to meet the pacemaker’s power draw requirement of 10 ± 1 µW. Therefore, this is the area of the device that will require the most improvement. Changes to the construction process or piezoelectric material would be essential for meeting the power requirement. Also, using a four-layer construction, as opposed to a two-layer construction, would improve the power output. Overall, the main success of this device was the PCB charging circuit that was designed. This circuit performed as expected and with refinement, to the piezoelectric device, this prototype could serve as a useful tool for the replacement of traditional pacemaker batteries. References [1] J. B. Goodenough and K. -S. Park, "The Li-Ion Rechargeable Battery: A Perspective, " Journal of the American Chemical Society, vol. 135, no. 4, pp. 1167 -1176, 2013. [2] A. Star, A. B. Kouki and C. Hung, "Power Approaches for Implantable Medical Devices, " MDPI Sensors, vol. 15, no. 11, 2015. [3] Medtronic, "Advisa DR MRI Sure. Scan A 2 DR 01 Specification Sheet, " November 2016. [Online]. Available: http: //www. medtronic. com/content/dam/medtroniccom/01_crhf/brady/pdfs/Rebranded%20 Advisa%20 DR%20 MRI%20 Spec%20 Sheet_201304249 b EN. pdf. [Accessed 29 November 2017] [4] “Biological evaluation of medical devices”. June 16, 2016. [Online] https: //www. fda. gov/downloads/medicaldevices/deviceregulationandguidance/guidancedocu ments/ucm 348890. pdf [Accessed April 6 2018] Figure 4: Test 1 Harvested Energy Figure 5: Test 2 Harvested Energy