2024

• Adam, Christian and Barth, Tobias and Schulz, Arndt-Peter and Bahr, Andreas
  Automatic Length Measurements in Hexapod Fixators Using Optical Proximity Sensors
  In Tagungsband "2024 31st IEEE International Conference on Electronics, Circuits and Systems (ICECS)", 2024, p. 1--4
  Nancy, 18.11.2024
  Abstract:
  Hexapod fixators are a specialized type of external fixators, which are used in the treatment of complex bone fractures. A set of metallic rings, which are attached to the bone fragments using wires and which are connected to each other by six length-adjustable struts, so-called distractors, enables a flexible and precise repositioning of fractures in six degrees of freedom. The lengths of the distractors define the configuration of the hexapod fixator and typically have to be iteratively adjusted over a period of several weeks. However, since the distractors are hard to reach for the patients, the length control is error-prone, limits the patient’s autonomy and can even require prolonged hospitalization. To overcome these limitations, a new system for automatically measuring the distractor lengths is proposed, which utilizes optical proximity sensors and wirelessly transmits the results to a reader device. The system achieves a measurement accuracy of less than 1 mm over the full measurement range of 105 mm. It can be powered autonomously from a small button cell for several weeks. With dimensions of 24 mm x 10 mm, the electronics module adds only little volume and weight.
  BibTeX:
  @inproceedings{adam_automatic_2024a,
  author = {Adam and Christian and Barth and Tobias and Schulz and Arndt-Peter and Bahr and Andreas},
  title = {{A}utomatic {L}ength {M}easurements in {H}exapod {F}ixators {U}sing {O}ptical {P}roximity {S}ensors},
  year = {2024},
  month = {11},
  booktitle = {2024 31st IEEE International Conference on Electronics, Circuits and Systems (ICECS)},
  note = {Nancy, 18.11.2024},
  pages = {1--4} }
  [Abstract] [BibTeX] [DOI]
  
  
• Adam, Christian and Münch, Matthias and Kleinschnittger, Patrick and Barth, Tobias and Schulz, Arndt-Peter and Bahr, Andreas and Krautschneider, Wolfgang
  Rapid prototyping of molds for the encapsulation of electronic implants using additive manufacturing
  Artikel in "Transactions on Additive Manufacturing Meets Medicine", vol. 6, Nr. 1, p. 1--8, 2024
  Abstract:
  Designing encapsulations for medical implants with integrated electronics is very challenging because a solution for several different and partly opposing requirements like biocompatibility, low water permeability, mechanical stability and small dimensions has to be found. This work focusses on epoxy encapsulations, which are conventionally cast using silicone molds. For making these molds, a pattern has to be CNC machined and the silicone mold has to be cast from it. In this paper, a rapid prototyping method is proposed, which uses additively manufactured molds made by an inkjet 3D printer that operates with a silicone-based material. A proof of concept is presented for an electronic osteosynthesis implant, which is successfully encapsulated following the rapid prototyping method and compared to results obtained with the conventional method. The demonstrator was immersed in isotonic saline solution for three weeks without any negative effects on the functionality. The rapid prototyping approach required only 15% of the time needed by the conventional mold making process based on silicone casting and used less material. This shortens design cycles for the optimization of the encapsulation for electronic implants and enables to evaluate more design variations with little additional effort. Moreover, designs with more degrees of freedom are available in the additive manufacturing process. For casting the encapsulation, the same material as for the final implant can be used so that many properties like water permeability and mechanical stability can be evaluated in the early development phase.
  BibTeX:
  @article{Adam:3D_printed_molds:2024,
  author = {Adam and Christian and M{\"u}nch and Matthias and Kleinschnittger and Patrick and Barth and Tobias and Schulz and Arndt-Peter and Bahr and Andreas and Krautschneider and Wolfgang},
  title = {{R}apid prototyping of molds for the encapsulation of electronic implants using additive manufacturing},
  year = {2024},
  month = {09},
  journal = {Transactions on Additive Manufacturing Meets Medicine},
  number = {1},
  pages = {1--8},
  volume = {6} }
  [Abstract] [BibTeX] [DOI]
  
  
• Rieseler, Jonas David and Adam, Christian and Bahr, Andreas and Kuhl, Matthias
  A Compressed Sensing Integrate-and-Fire Neuron Concept for Massively Parallel Recordings
  In Tagungsband "2024 IEEE International Symposium on Circuits and Systems (ISCAS)", 2024, p. 1--5
  ISSN: 2158-1525
  Abstract:
  A compressed sensing integrate-and-fire neuron concept for massively parallel recordings is presented which expands the fundamental idea of superimposing timely sparse signals for data compression to any kind of continuous-time signals. Merging compressed sensing and amplitude-to-spike conversion, the proposed approach increases the information density and reduces the channel load. Combining multiple data-compressive neurons as a sensing array, further compression can be achieved when the spikes from different recording sites are superimposed on a single transmission channel. Signal reconstruction quality and transmission channel load are investigated to provide a strategy for selecting the design parameters of the proposed system. A proof-of-concept is presented, where a load per recording channel of 1 % under a relative reconstruction error of 0.32 % (SNR = 25 dB) is achieved.
  BibTeX:
  @inproceedings{Rieseler:Compressed_Sens:2024,
  author = {Rieseler and Jonas David and Adam and Christian and Bahr and Andreas and Kuhl and Matthias},
  title = {{A} {C}ompressed {S}ensing {I}ntegrate-and-{F}ire {N}euron {C}oncept for {M}assively {P}arallel {R}ecordings},
  year = {2024},
  month = {05},
  booktitle = {2024 IEEE International Symposium on Circuits and Systems (ISCAS)},
  note = {ISSN: 2158-1525},
  pages = {1--5} }
  [Abstract] [BibTeX] [DOI]
  
  
• Yang, Cheng and Adam, Christian and Götschel, Sebastian
  Complex Near-Field Measurement Using On-The-Fly Scan with In-phase and Quadrature Demodulation
  In Tagungsband "2024 15th German Microwave Conference (GeMiC)", 2024, p. 181-184
  Duisburg, Germany, 2024
  Abstract:
  Recently, a new near-field measurement technique based on on-the-fly (OTF) scanning and a Hilbert transform (HT) was proposed, allowing for rapid phase retrieval using a single probe. However, because of the required Nyquist rate sampling, this method encounters challenges related to costly data acquisition, storage, and processing demands, thereby restricting its use at MHz and GHz frequencies. In this paper a novel method is proposed, which addresses these issues by introducing in-phase and quadrature (IQ) demodulation in place of the HT. Its inherent frequency down conversion of the measured signal enables sampling at a significantly lower rate. To demonstrate the effectiveness of the proposed method, it is employed in a near-field scanner to measure the magnetic fields of two distinct devices under test: a wireless power transmitter and a microstrip line, operating at 125 kHz and 1 GHz, respectively. Measurement results, compared to conventional field measurement approaches, show a good correlation, affirming the suitability of this fast and cost-effective solution for antennas, and RF systems.
  BibTeX:
  @inproceedings{yang_otf-scan-iq-demod_2024,
  author = {Yang and Cheng and Adam and Christian and G{\"o}tschel and Sebastian},
  title = {{C}omplex {N}ear-{F}ield {M}easurement {U}sing {O}n-{T}he-{F}ly {S}can with {I}n-phase and {Q}uadrature {D}emodulation},
  year = {2024},
  month = {03},
  booktitle = {2024 15th German Microwave Conference (GeMiC)},
  note = {Duisburg, Germany, 2024},
  pages = {181-184} }
  [Abstract] [BibTeX] [DOI]
  
  

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