Biological effects of piezoelectric ceramics listen
This article explores a new simple method, the piezoelectric ceramic diaphragm cochlear implants, the use of materials, piezoelectric effect, the acoustic signals into electrical signals directly stimulate the auditory nerve to Xin replace expensive, complex electronic cochlea so deaf ear to regain hearing which will benefit hundreds of foolproof deaf patients.
To this end, we find a niobate piezoelectric ceramics, good stability, excellent value, frequency constant large biological phase pits good. After knocking implants made of thick small piece of 15 guinea pigs deafness, deaf ears hearing improve 40 ~ 50dB piezoelectric ceramic display good biological listen effects may develop into a new generation of artificial auditory organ.
Over the last decade, at home and abroad in the hearing or artificial cochlea (electrodes) implanted deaf patients to reconstruct aspects of auditory function a lot of research work. Cochlear implants (also known as electronic cochlea or cochlear implants), has enabled some deaf people to regain a part of the whole practical value of hearing, so that has always been considered unsolvable sensorineural hearing loss have a new hope.
A cochlear implant is a transducer that converts an acoustic signal through the microphone into an electrical signal, the electrical signal amplified by the processor, and then delivered to the sensors embedded in the skin by the receiver, and finally transmitted to the cochlear implant in the platinum-iridium alloy or platinum electrodes, stimulation to the auditory nerve, resulting in hearing. cochlear design and manufacture are quite complex, expensive, not widely used. America's most famous House cochlear implant specialists, who believe that only when the device is better when produced, the number of suitable implants will greatly increase, in order to raise awareness of the data analysis, the promotion of research cochlear made significant progress.
New technologies, new materials, new technology combine to forge new ground in the field of biological engineering. This article explores a new approach, without expensive and complex structure of the device, using a piezoelectric ceramic new functional materials, the piezoelectric effect after cochlear implantation can simulate cochlear transducer function directly to the acoustic signals into electrical signals, stimulate the auditory nerve to the hearing.
Healthy white red mesh adult guinea pigs, weighing 250 ~ 350g, were male, reflecting the normal ear, auditory brainstem response (ABR) were measured listen Min 20 ~ 30dB, were randomly divided into control group after blast deafened 5 l5 and surgical experimental group only, which are experimental ear left ear, right ear as the control ear.
2.2 knock deafness Methods: D a 86 EDM pulse sounder for sound source, the external ear canal with a distance of about animal lOcm, the angle of incidence of 45. Knocking sound pressure peak 167: t: 2dB SPL, pulse width 0.1ms. Total knock of 100 to 120 times, each time interval of 3s.
2.3 ABR test: guinea pig animal clip into a special wooden box-type fixed, awake testing. Short sound stimulation intensity range between 10 ~ 90dB SPL, 1024 superimposed stimulus intensity, stimulus interval 75ms, scan time 20ms, filter range 80 ~ 150Hz. Before knocking, knocking before after surgery, immediately after surgery, after two days, seven days, l5 days and 30 days respectively, hearing threshold test.
2.4 implant materials: Choose a niobate piezoelectric ceramic thick film, provided that: (1) high Curie temperature (> 400 ℃), good stability; (2) of the dielectric coefficient, excellent value high (<1ooo), easy to adjust; (3) frequency constant too, easy to control bandwidth practical devices; high (4) mechanical strength, and ease into thick; (5) lead-free non-toxic. Implant material specifications ix2xO. 05ram. Surface coated silver electrode.
2.5 surgical methods: thiophene compound guinea pigs injected ketamine (0.1mL / kg), 5rain onset of action. The guinea pig limbs fixed on the operating table. After taking ear incision under a surgical microscope, revealing the cochlea with an electric drill from the mastoid into the road, at the bottom of the round window in 1ram mill open cochlear bone wall lx3mm. The small piece of piezoelectric ceramic implants thus scala tympani, taking on the promontory bone meal closed holes, dropping to fibrin adhesive fixed. Sutured incision surgery ended.
2.6 light microscope: After surgery in January to kill the control and operation of live guinea pigs. Take control group two cochlear ear, ear surgery group 6, lo% formalin-fixed after using collodion embedding do biopsy, light microscopy examination.
3 Results and Discussion
3.1 two guinea pigs (40 ears) before knocking listen Fujian Normal, were at 20 ~ 30dB, after knocking up to 80dB Min listen above all have a threshold shift of more than 40dB, the maximum threshold shift 60dB. Generally recognized: 8h threshold shift after knocking guinea> 40dB who listen to Min change is irreversible, called a permanent shift valve. In this paper, the control group and the surgery group also confirmed the determination of the control ear ABR · guinea pigs before and after detonation, auditory brainstem response threshold was measured before and after implantation of a piezoelectric ceramic results in Table 1.
2.jpg
Histological examination after knocking cochlear outer hair cells of Corti severity of injury, there is the nucleus disappears, cell fusion or missing, and listen to the physiological study results are consistent. Guinea pig cochlea light microscopy examination results without surgery after knocking in Figure 1.
3.jpg
3.2 Saw salt piezoelectric ceramic material deafness in guinea pig cochlea implants knock instantly measure ABR, part of that decline valve surgery ears, some ears valve surgery no significant changes in the Department of Surgery reaction may cause. Two days after surgery all ears valve begins to significantly decrease until after January listen valve down 40 a ∞dB, a significant difference (P <Om) and the control ear.
