A Non-Radiative Wireless Power Transfer System for Medical Implant Deployment: An Experimental Validation

Abstract

Wireless Power Transfer (WPT) systems employing magnetic resonance technology offer a compelling solution for providing seamless power delivery in scenarios where conventional electrical connections are impractical. This research focuses on designing and developing a magnetic resonance-based WPT system explicitly tailored for powering battery-operated pacemakers, addressing the limitations posed by traditional wired connections, particularly in medical contexts. Through numerical modelling and experimental validation using a constructed test-rig setup, the performance of the WPT system was assessed, with a specific emphasis on input–output power efficiency. The results demonstrate efficient power transmission from the transmitter to the receiver over a separation distance of 100 mm. Experimental validation further corroborates the effectiveness and reliability of the developed system, yielding a high correlation coefficient of 0.98. This research advances the wireless power transfer field, particularly in medical device applications, paving the way for enhanced patient care and technological innovation.

Appendices

Appendix

1.1 A: Design Parameters

1.1.1 A.1: Inductance of a Circular Coil

$$\begin{aligned}{} & {} = N^{2} \mu 0 r ( \hbox {ln}(8r/a) - 1.75 )\\{} & {} = 9^{2} x 4\pi x 10^{-7} x 8 x ( ln( (8x8)/0.4 ) -1.75 ) = 2.707\hbox {mH} \end{aligned}$$

1.1.2 A.2: Resistance of the Winding

Resistance of the Winding (R) = $\rho$l/A

Length of the coil (l) = Circumference of coil x N

= 2$\pi$ x D x N

= 904.8cm

A = 2$\pi$r(r+h), where, h = width of the winding

= 442.34cm

P = Resistivity of Copper = 1.796x$10^{-8}$

R = 3.67x$10^{-8}$ $\varOmega$

1.1.3 A.3: Resistance of Leakage Path

R = $\rho$l/A

P = Resistivity of Air = 106 (assumed)

l = length of air gap = 6.5cm ( Distance to be transmitted )

A = Area of air gap ( Rectangular Area between two coils )

R = 1.54 M$\varOmega$

1.1.4 A.4: Resonant Frequency

f = 1/2$\pi \sqrt{LC}$

L = 2.707mH

C = 0.0047nF ( Capacitor Used )

f = 1.4 MHz

1.1.5 A.5: Resonance Condition

For Resonance to occur, $X_{L}$ = $X_{C}$ $X_{L}$ = Inductive reactance $X_{C}$ = Capacitive reactance

$X_{L}$ = 2$\pi$ x f x L = 23812 $\varOmega$ = 23.8 k$\varOmega$

$X_{C}$ = 1/2$\pi$ x f x C = 24188 $\varOmega$ = 24.188 K$\varOmega$

B: Hardware Testing

1.1 B.1: Continuity Test

A consistency evaluation in electronics is the testing of an electric circuit to see how current flows. A continuity check is carried out by putting a small voltage over the chosen path. The circuit is open when electron flow is inhibited by broken conductors, damaged components, or excessive resistance. This check seeks to identify some available electrical pathways in the circuit following the soldering phase. Often the electrical stability of the circuit is lost due to poor soldering, incorrect and harsh handling of the PCB, inappropriate use of the soldering hammer, defects of the connectors, and flaws in the circuit diagrams. We hold the multimeter in buzzer mode and connect the multimeter ground terminal to the ground. We link both terminals over the path to be tested. When there is continuity, otherwise, you’ll hear the sound of the beep.

1.2 B.2: Power on Test

This test is to verify whether or not the voltage at various terminals is as per the requirement. We are taking a multimeter and placing it in voltage mode. If we use a transformer, we check the transformer output, whether we are getting the required 12V AC voltage (depending on the transformer used in the circuit). If we use a battery, then use a multimeter to test if the battery is ultimately charged or not according to the battery voltage stated. Then we add this voltage to the circuit supplying power. Note that we perform this test without ICs, which will harm the ICs if there is any excess voltage. When a circuit consists of a voltage regulator, we test for the input to the voltage regulator (such as 7805, 7809, 7815, 7915), i.e., we get a 12V input and a correct output based on the controller used in the circuit. Example: if we use 7805, we get 5V output, and if we use 7809, we get 9V at the pin output and so on. Relevant ICs send this output from the voltage regulator to the power supply board. Therefore we test if we get the appropriate voltage for the voltage level at those pins.