title: Energy-Efficient SMPS-Based Pulse Generator for Neurostimulators

authors: Seshadri, Sinduja

subjects: pulse generator

abstract: There is a need in the neuromodulation industry for a very energy-efficient pulse generator. Little data is observed in literature to develop a power efficient pulse generator that can deliver the required stimulus. A typical stimulator has a boost stage, a low-dropout (LDO) stage and an analog circuit that delivers the stimulus in the form of a pulse to the patient. Such a system is found to be ∼ 40% efficient. There are two new methods that can improve this efficiency rating significantly. (1) A mod- ification to existing pulse generator by adding microprocessors to control the output voltages of boost and LDO in the circuit, as proposed by the manufacturer; (2) a Single-Ended Primary Inductance Converter (SEPIC) based design proposed by the authors, with the input connected to a battery and the output to electrodes. Comparing with existing design, the modification offered a consistent 75% efficiency for output voltages from 3.9V to 6.6V. SEPIC had an efficiency rating of 80% to 86% across the same voltage range.

text: Energy-Efficient SMPS-Based Pulse Generator for Neurostimulators There is a need in the neuromodulation industry for a very energy-efficient pulse generator. Little data is observed in literature to develop a power efficient pulse generator that can deliver the required stimulus. A typical stimulator has a boost stage, a low-dropout (LDO) stage and an analog circuit that delivers the stimulus in the form of a pulse to the patient. Such a system is found to be ∼ 40% efficient. There are two new methods that can improve this efficiency rating significantly. (1) A mod- ification to existing pulse generator by adding microprocessors to control the output voltages of boost and LDO in the circuit, as proposed by the manufacturer; (2) a Single-Ended Primary Inductance Converter (SEPIC) based design proposed by the authors, with the input connected to a battery and the output to electrodes. Comparing with existing design, the modification offered a consistent 75% efficiency for output voltages from 3.9V to 6.6V. SEPIC had an efficiency rating of 80% to 86% across the same voltage range.

year: 2019

title: Exploring the Lewis basicity of the metalloligand [Pt₂(μ-Se)₂(PPh₃)₄] on metal substrates by electrospray mass spectrometry. Synthesis, characterization and structural studies of new platinum selenido phosphine complexes containing the {Pt₂Se₂} core

authors: Yeo, Jeremy S.L.

subjects: chemistry

abstract: Electrospray Mass Spectrometry (ESMS) has been used as a tool to probe the reactivity of the metalloligand [Pt₂(μ-Se)₂(PPh₃)₄] with metal substrates, which lead to the formation of charged coordination complexes via loss of halides or other labile ligands. Among the numerous metal substrates used in the displacement reactions are Au(anpy)Cl₂ (anpy = cyclometallated 2-anilinopyridyl), HgPhCl and Pb(NO₃)₂. Acid titration on the Lewis basic metalloligand leads to the identification and isolation of the doubly-protonated species, [Pt₂(μ-SeH)₂(PPh₃)₄]²⁺, whose sulfide analogue cannot be isolated. A three-step strategy is employed in the use of ESMS as a probe: (i) preliminary screening of the metalloligand with an array of acidic main group and transition group metal compounds, (ii) identification of potentially stable and isolable products formed in situ based on ion distribution and simulated isotope patterns and (iii) promising reactions are repeated on a laboratory scale, and target products are isolated and characterized. X-Ray diffraction studies have been performed on single crystals of [Pt₂(μ-SeH)₂(PPh₃)₄][ClO₄]₂, [Pt₂(μ₃-Se)₂(PPh₃)₄(CdCl₂)] and {Pt₂(μ₃-Se)₂(PPh₃)₄[Pb(NO₃)]}{NO₃}. These results suggested that in general a parallel chemistry can be developed on the intermetallic selenides as on the sulfides. However, there are chemical and structural differences which are highlighted in this paper.

text: Exploring the Lewis basicity of the metalloligand [Pt₂(μ-Se)₂(PPh₃)₄] on metal substrates by electrospray mass spectrometry. Synthesis, characterization and structural studies of new platinum selenido phosphine complexes containing the {Pt₂Se₂} core Electrospray Mass Spectrometry (ESMS) has been used as a tool to probe the reactivity of the metalloligand [Pt₂(μ-Se)₂(PPh₃)₄] with metal substrates, which lead to the formation of charged coordination complexes via loss of halides or other labile ligands. Among the numerous metal substrates used in the displacement reactions are Au(anpy)Cl₂ (anpy = cyclometallated 2-anilinopyridyl), HgPhCl and Pb(NO₃)₂. Acid titration on the Lewis basic metalloligand leads to the identification and isolation of the doubly-protonated species, [Pt₂(μ-SeH)₂(PPh₃)₄]²⁺, whose sulfide analogue cannot be isolated. A three-step strategy is employed in the use of ESMS as a probe: (i) preliminary screening of the metalloligand with an array of acidic main group and transition group metal compounds, (ii) identification of potentially stable and isolable products formed in situ based on ion distribution and simulated isotope patterns and (iii) promising reactions are repeated on a laboratory scale, and target products are isolated and characterized. X-Ray diffraction studies have been performed on single crystals of [Pt₂(μ-SeH)₂(PPh₃)₄][ClO₄]₂, [Pt₂(μ₃-Se)₂(PPh₃)₄(CdCl₂)] and {Pt₂(μ₃-Se)₂(PPh₃)₄[Pb(NO₃)]}{NO₃}. These results suggested that in general a parallel chemistry can be developed on the intermetallic selenides as on the sulfides. However, there are chemical and structural differences which are highlighted in this paper.

year: 2002

title: Worlded object and its presentation: A Māori philosophy of language

authors: Mika, Carl Te Hira

abstract: In an era concerned with the survival of Indigenous languages, language as a general phenomenon needs to be thought of as thoroughly connected to one’s worldview. In this article, I propose a different conception of language that sides more with what I call ‘the worlding of things’ than linguistics. To foreshadow my speculations on language, I consider the possibility that, within the representation of one entity in perception, there exist all other entities. An entity is hence ‘worlded’—a key aspect of the term ‘whakapapa’. I then turn to think about language as a general phenomenon for Mäori, and its complex ability to world an entity even as it adumbrates that thing’s backdrop. I consider the verb ‘to be’ in that light, arguing that Mäori identify language as a sort of gathering of entities rather than an instrument for singling out one thing as thoroughly and separably evident. This article is therefore as much about the full participation of the world as it is about language; it also aims to counter the belief that language is merely a conveyor of ideas.

text: Worlded object and its presentation: A Māori philosophy of language In an era concerned with the survival of Indigenous languages, language as a general phenomenon needs to be thought of as thoroughly connected to one’s worldview. In this article, I propose a different conception of language that sides more with what I call ‘the worlding of things’ than linguistics. To foreshadow my speculations on language, I consider the possibility that, within the representation of one entity in perception, there exist all other entities. An entity is hence ‘worlded’—a key aspect of the term ‘whakapapa’. I then turn to think about language as a general phenomenon for Mäori, and its complex ability to world an entity even as it adumbrates that thing’s backdrop. I consider the verb ‘to be’ in that light, arguing that Mäori identify language as a sort of gathering of entities rather than an instrument for singling out one thing as thoroughly and separably evident. This article is therefore as much about the full participation of the world as it is about language; it also aims to counter the belief that language is merely a conveyor of ideas.

year: 2016