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Middle Ear Implants
Published in John C Watkinson, Raymond W Clarke, Christopher P Aldren, Doris-Eva Bamiou, Raymond W Clarke, Richard M Irving, Haytham Kubba, Shakeel R Saeed, Paediatrics, The Ear, Skull Base, 2018
Maarten J.F. de Wolf, Richard M. Irving
For an MET/Carina device, the bone work is away from the facial nerve but perhaps less familiar to the otologist. An atticotomy is performed to expose the incus body and malleus head. A laser is used to make a hole in the body of the incus. The transducer is then inserted into the mounting system secured to the skull and the probe tip is aligned with the laser-made hole in the incus. Fine-positioning of the probe tip is made by screw adjustment.8 For the Carina, a separate microphone connected to the implanted sound processor is placed in a postauricular subcutaneous pocket. For the Esteem system a large facial recess opening is needed so that resection of chorda tympani is often inevitable. Intra-operative testing by means of laser Doppler vibrometry is needed to assess the mobility of the incus and stapes. Hypomobility will require aborting the surgical procedure at this point. Meticulous cleaning of the stapes head and incus is needed for adequate placement of the sensor and driver.
Piezoelectric Thin Films for MEMS Applications
Published in Iniewski Krzysztof, Integrated Microsystems, 2017
The measurement setup of the piezoelectric thin films is shown in Figure 32.5. For the measurement of piezoelectric properties of the PZT films on MgO or Si substrates, we cleaved the substrates into beam shape with a size of around 15 × 2.5 mm2. Then the thin Au or Pt top electrode was evaporated over the surface of the PZT films. Finally, the edge of the beam was clamped using a vise and unimorph cantilevers composed of PZT film and substrate were prepared. The dimension of the cantilevers is listed in Table 32.2. Piezoelectric vibration is generated by means of applying sine wave voltage between upper and bottom electrodes, and the tip displacement was measured using a laser Doppler vibrometer. The electric contact of the bottom electrode was obtained from the clamped edge, whereas the upper electrode was connected to a fine lead line using silver paste not to disturb the piezoelectric actuation. From the tip displacement of the cantilever, the transverse piezoelectric properties of the PZT films were evaluated.
Scale-Up and Transfer of Hard Shell Formulations across Machine Types
Published in Larry L. Augsburger, Stephen W. Hoag, Pharmaceutical Dosage Forms, 2017
Larry L. Augsburger, Michael Levin
Air compressors, vacuum pumps, and the drive motor all contribute to filling machine vibration and the greater vibration realized at higher running speeds may increase powder density and fill weight in dosator machines. Llusa et al.16 fitted a laser Doppler vibrometer to a research MG2 machine (Labby). They found that machine vibrations were not significant at a running speed of 500 cph, and powder density was not measurably affected. At 3000 cph, vibration and powder bed densification were significant and fill weight was significantly increased. The study was limited to a single capsule size (#3) and the filling of several grades of microcrystalline cellulose. No lubricants (i.e., magnesium stearate) were included, which could have modified their findings owing to the ability of magnesium stearate often to enhance the initial packing density of powder blends and form denser plugs, including those formed from microcrystalline cellulose. For example, Shah et al.7 found the bulk and tapped densities of microcrystalline cellulose (Avicel PH 101) to increase with the percent magnesium stearate within the concentration range of 0.1–0.5%. The weight and breaking strength of the plugs formed from these lubricated blends on an instrumented H&K 330 dosing disc machine were greater than were found with the unlubricated filler. The 0.1% level appeared optimal in that it resulted in maximum weight and plug breaking strength. At the 0.25% and 0.5% levels, breaking strength decreased with magnesium stearate concentration, but weight exhibited little change. The lubricant effects that contribute to plug breaking strength and those that tend to soften plugs appear competitive, with those contributing to softening dominating at the higher magnesium stearate levels. In another example using a tabletop plug-forming device, Jones17 found that plug density increased with mixing time when 1% magnesium stearate was added to either microcrystalline cellulose (Avicel PH 102) or pre-gelatinized starch (Starch 1500). Such densified formulations may have limited ability to undergo further vibrational densification in the machine. Nevertheless, the direct observation of significantly increased vibratory consolidation of a powder bed at the high running speed is a significant finding for dosator machines for which powder bed density is a significant determinant of fill weight. However, the significance of this finding should not be limited to dosator machines since vibratory consolidation can occur in both dosator and dosing disc machines. Considering the operational characteristics of these machines, vertical vibration may be more important in dosing disc machines. Beyond effects on fill weight, increased vibration at higher speeds could also encourage segregation in susceptible formulations. The reader is referred to Lin et al.18 for a useful analysis of the relationship between bulk powder properties and the segregation tendency of powder formulations from a Quality by Design perspective.
Total auricular reconstruction concomitant with BONEBRIDGE implantation using a retrosigmoid sinus approach
Published in Acta Oto-Laryngologica, 2022
Danni Wang, Bingqing Wang, Ran Ren, Yue Wang, Jinsong Yang, Peiwei Chen, Shouqin Zhao, Qingguo Zhang
The BONEBRIDGE is an active bone conduction hearing implant whose vibrator need to be assembled in the temporal bone. At present, the common surgical approaches include the sinodural angle (SA), retro-sigmoid sinus (RS) and middle fossa approaches. Sprinzl and Wolf-Magele pointed out in a systematic review [3] that undefined all the surgical approaches have proven to have good benefits for patients with conductive hearing loss or mixed hearing loss in both functional gain and speech reception. In some researches, laser Doppler vibrometry has been used to measure vibration of cadaveric temporal bones to compare efficiency of the three implantation sites, as well as vibrational displacement of the cochlear bone wall while using a Lift, but no statistical difference was found [11].
Round window and promontory movements during bone conduction with different middle ear conditions in Thiel embalmed specimens
Published in Acta Oto-Laryngologica, 2019
Christof Stieger, Martin Kompis, Marco Caversaccio, Jérémie Guignard, Andreas Arnold
Besides the kind of specimen conservation used, the method used to measure the effect of bone conduction stimulation is important when comparing the results of different studies. In cadaveric studies, accelerometers mounted on the promontory [8] or laser Doppler vibrometry (LDV) have been used. Recently BC has been studied with micro-fibre-optic pressure sensors placed inside the scala vestibuli and scala tympani [9,10]. This method enables the determination of the pressure across the partition of the cochlea, which has been shown to be proportional to the amplitude of cochlear action potentials (CAP) [11]. For comparison of changes in BC within the same study object, contactless LDV on the promontory and RW is technically far less complex and avoids penetration of the cochlea bony wall. Nonetheless, the question arises, whether the sensitivity of measurements close but still outside the cochlea is enough to detect the effect of different middle ear conditions on BC.
Comparison between incus short process and long process coupling of the vibrant soundbridge in human temporal bones
Published in International Journal of Audiology, 2023
Lukas Graf, Jonas Lochner, Hamidreza Mojallal, Andreas Arnold, Flurin Honegger, Christof Stieger
Schraven et al. (Schraven et al. 2014) reported another attachment for use in patients with sensorineural hearing loss and an intact ossicular chain, connecting an original LP crimp (VORP 502) to the short process of the incus (SP). Their experimental work in human temporal bone specimens using laser Doppler vibrometry (LDV) measurements showed similar magnitudes in motion compared to the standard LP coupling. The surgical procedure for SP coupling requires an antrotomy without the additional posterior tympanotomy for LP coupling (Schraven et al. 2014).