Doctors as poets: laudatory verses addressed to Antonio Molinetti by British medical students at Padua, 1650-4.
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History, 17th Century↗
Biomedical subjects
D K Money
Publications and source records attributed to D K Money.
Comparative reliability of cochlear implants.
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Cochlear Implants↗
Histological evaluation of porous titanium cardiac pacemaker electrode tips.
An investigation of the tissue reaction to five porous titanium alloy pacemaker electrode tips inserted in sheep hearts was made. Attachment of the electrode tips to the endocardial wall was facilitated by fibrous tissue ingrowth into the porous material. Vascularized fibrocollagenous tissue was found within the pores of the tips. One tip was found to be infected. The presence of occasional multinucleated foreign-body giant cells within the porosity was related to the particulate features of the porous tip. The electrode tips had a reduced sensing impedance compared with conventional solid platinum tips. The present findings are consistent with previous observations relating to porous cobalt-chromium alloy and porous platinum-iridium alloy tips and suggest that porous titanium alloy may be a suitable pacemaker electrode tip material.
Alloys↗
The nucleus multi-channel implantable hearing prosthesis.
The Nucleus Multi-channel Implantable Hearing Prosthesis was developed in conjunction with the University of Melbourne. A 22 channel flexible electrode array is inserted into the cochlea through a round window opening. A cable leads from the electrode array to a demountable connector mounted on the Receiver-Stimulator unit (RSU). A custom CMOS integrated circuit is mounted inside the hermetically sealed titanium and ceramic RSU which is encased in silicone rubber and measures 34.5 mm diameter and 10.5 mm thick. Biphasic current pulse stimuli can be delivered to any selected electrode pairs at rates in excess of 1 kHz. A pocket-sized speech processor extracts spectral information from the incoming acoustic signal, and encodes stimulus information onto the single RF power/data signal transmitted to the RSU through the skin. The Speech Processor includes electronic memory circuits which are programmed with the information mapping acoustic parameters to stimulation parameters for each electrode for each patient. This MAP is established as a result of psychophysical experiments performed by the audiologist using the Diagnostic and Programming System based on a customized microcomputer.
Cochlear Implants↗
Screening of solid and porous materials for pacemaker electrodes.
Several different materials, including one which was porous, were studied to assess their properties as pacemaker electrode tips. Leads were implanted in sheep for periods up to one year. Electrical measurements were made during the implant period and histopathological examination performed after sacrifice. Although titanium vapor-deposited carbon, and silver did not lower the chronic stimulation threshold below that of platinum, their electrical characteristics were within generally acceptable limits. Zinc evoked a severe tissue reactions and a high threshold. Porous titanium alloy electrodes demonstrated reduced dislodgement, more frequent attachment and a lower sensing impedance than other electrodes.
Alloys↗
A multi-channel hearing prosthesis for profound-to-total hearing loss.
A multi-channel cochlear implant hearing prosthesis providing 22 separate channels of stimulation has been developed. The electronics for the implantable receiver-stimulator have been incorporated on a single chip, using digital circuits and employing CMOS technology. The chip is enclosed in a titanium capsule with platinum/ceramic electrode feed-throughs. A pocket-sized speech processor and directional microphone extract the following speech parameters: signal amplitude, fundamental frequency and formant frequency. The fundamental frequency is coded as electric pulse rate, and formant frequency by electrode position. The speech processor has been realized using hybrid circuits and CMOS gate arrays. The multi-channel prosthesis has undergone a clinical trial on four postlingually deaf patients with profound-total hearing losses. The speech perception results indicate that they were able to obtain open-set speech recognition scores for phonetically balanced words, CID sentences and spondees. In all cases the tests showed significant improvements when using the cochlear prosthesis combined with lipreading compared to lipreading alone.
Adult↗