Research And Design Of Implantable Laryngeal Pacemaker

Vocal cord paralysis will damage to the breathing, pronunciation and swallowing functionof throat. In severe cases, it can lead to breathing difficulties and life-threatening. It has neverbeen a good solution for this problem. Although traditional treatment methods can improvebreathing, the function of voice and swallowing will be damaged. It is difficult to take intoaccount to restore all the three function of larynx. Medical researchers found that the use ofrespiratory-synchronized electrical stimulation pulses to stimulate the cricoarytenoid musclecan improve breathing of the patients of vocal cord paralysis by increasing the open area ofglottal, and will not affect swallowing and pronunciation function. The electrical stimulationdevice for the treatment of vocal cord paralysis is known as the laryngeal pacemaker.In this paper, the principle of the laryngeal pacemaker treatment of vocal cord paralysis isstudied. An implantable pressure sensor of chest is used to get the respiratory signal.According to the characteristics of the respiratory signal, a hardware circuit is designed toamplify, filter and denoise the respiratory signal. After these processing, a clean, completebreathing waveform is obtained. A circuit based on MSP430is designed to process therespiratory. To obtain the trigger signal from respiratory, a method which judges the trend ofrespiratory waveform and detects the extreme points of respiratory waveform is used. Thiseffectively solved the problem of swallowing, pronunciation, and cough caused by a suddenimpact. For the different situations of patients with vocal cord paralysis, laryngeal pacemakercan generate bipolar stimulation pulses with parameters such as pulse width, frequency andamplitude adjustable to stimulate the posterior cricoarytenoid muscle, and increase theirglottis open area. That can effectively solve the vocal cord paralysis. To solve the problem oflong-term supply of energy, implantable battery provides energy for the laryngeal pacemaker,and wireless energy transmission circuit charge the battery. First a model of the chargingcircuit and the coupling coil is established. With this model, a single-end flyback circuit basedon TL494is designed to charge the battery. And the charging process is controlled byfeedback of secondary coil. These measures successfully solve the energy supply problem.For the problem of exchang information in vitro and in vivo, a wireless communication circuitbased on CC2430is designed. In addition, this communication circuit is also cleverly used tomonitoring the wireless transmission circuit and giving feedback to the circuit in vitro. And itimproves the stability and security of the wireless energy transfer circuit. In the design oflaryngeal pacemaker, low-power design methods and miniaturization of circuit design method is also fully taken into account.Laryngeal pacemaker can effectively solve the problem of the vocal cord paralysis.However, the domestic development on implantable laryngeal pacemaker has not yet started.In this paper, as a project, the implantable laryngeal pacemaker is researched and designed.The method of trend detection and extreme points to determine is originally used to access tothe trigger signal from the respiratory signal. And a wireless charging circuit which can becontrolled by wireless communication circuit is designed according to the advanced andreliable Qi wireless charging standard to provide energy for the laryngeal pacemaker. Thisbrings great convenience to the patients with vocal cord paralysis, and provides a guidelinefor the solution to the problem of energy supply for implantable device, and also will bringhuge economic and social benefits.