Technical constrains

Technical specifications

Item Target Achieved Completion status
Spatial resolution (mm) longitudinal : 1mm
lateral : 1mm
to be quantified -
Number of transducers 3 1 (transducer A) 33%
Angular sector (°) 60 60 100%
Number of lines 128 64-128 100%
Framerate (fps) 10-20 2 10-20%
Cost (€) 500 1200 40%

Transducer characteristics

Transducer Frequency (MHz) Focal distance (mm) Maximal depth (mm)
A 3.5 50-150 200
B 5 30-105 150
C 7.5 10-75 100

PBL-mec : Mechanics

This is a classification of the mechanical constraints. The main constraint is to design a mechanical device to scan a 60° sector with an ultrasonic beam 15 times per second. This constraint can be divided into several constraints, that can be specified too. An ID is attributed to each of the constraints, taking their dependences into account. This creates a kind of "tree structure".

PBL-mec_scn : scanning mechanism

Design a mechanical device to scan a 60 ° sector with an ultrasonic beam 15 times per second.

PBL-mec_scn_mov : Choose between oscillating and continuous rotary motion

Choose the type of movement of the ultra-sound beam and design the mechanism by which it can be obtained (continuous rotating, oscillating, acoustic mirrors, etc.)

PBL-mec_scn_mov_mot : Motorization

Choose or design a type of motorization to obtain the chosen movement.

  • PBL-mec_scn_mov_mot_drv : Motor electronic driver

Design or choose an electronic driver for the selected motor.

  • PBL-mec_scn_mov_mot_enc : Position sensors

Design a means of knowing the position of the transducer during its movement.

  • PBL-mec_scn_mov_mot_firm : Controller firmware

Design a firmware capable of controlling the motion of the transducer using the position encoder(s) and the selected motor.

     PBL-mec_scn_mov_cnx : Transducer / electronic card connection

Design an electrical connection for carrying the signal between the mobile transducer(s) and the fixed electronic processing PCB.

     PBL-mec_scn_mov_brk : Transducer support

Design a bracket suitable for receiving the transducer capsule without interfering with ultrasonic emission or impeding maintenance.

PBL-mec_scn_tri : tri-frequency

To address several medical use cases, 3 transducers with different frequencies (respectively 3.5, 5 and 7.5 mHz) are expected to be incorporated in the probe. Image acquisition will be performed with one transducer at a time. Choose between interchangeable and tri-frequency probe. Design the device to move three different transducers resonating at 3.5, 5 and 7 MHz.

PBL-mec_us : Acoustic continuity

Ensure the continuity of acoustic impedance between the transducer surface and the body of the patient.

PBL-mec_us_oil : Oil

Design a system to immerse the sensor in an acoustically compatible liquid bath.

     PBL-mec_us_oil_sel : Selecting oil

Select a liquid (a priori an oil) that meets the following criteria:

  • Low-cost
  • Organic Compatibility
  • Acoustic compatibility
  • Electrical compatibility
  • Material compatibility
  • Good durability

       PBL-mec_us_oil_seal : Sealing

Design all systems that seal the oil-containing enclosure:

  • Choice of what is immersed in oil: piezo / mechanism / motor / position sensors / PCB / battery.
  • Type of seals: static on housing, static on cables, dynamics on shaft, flexible.
  • Seal material maintainability: removable or glued.

       PBL-mec_us_oil_fil : Filling

Design the procedure for filling the cavity containing the oil:

  • Filling hole
  • Air bubble removal system
  • Pre-maintenance dumping (protection of dry areas)

    PBL-mec_us_case : Case

The part of the case that will be traversed by the ultrasounds must have a shape and be in a material compatible with this function.

     PBL-mec_us_case_mat : Material

Select a material that is as transparent as possible to ultrasound, while remaining low-cost and easy to use. Several parts of different materials may be considered.

     PBL-mec_us_case_shp : Shape

The portion of the housing which will be in contact with the skin of the patient will have to have a minimum radius of curvature in order, for example, to allow examination between two ribs.

    PBL-mec_us_gel : Gel

Design or select a recipe for the gel used to ensure good continuity between the case and the patient's skin. This recipe should be low-cost and easily achievable.

PBL-mec_nrg : Energy

Design a power system that meets the needs of the echOpen probe in terms of autonomy, safety, space, ease of use and cost.

PBL-mec_nrg_bat : Battery type

Select the good battery type

PBL-mec_nrg_load : Loading

Design the recharging system, either wired through a sealed plug or by induction.

PBL-mec_nrg_therm : Thermal Management

The response of the system to the various thermal stresses will be studied:

  • Internal heating (motor, electronics, battery) during operation or charging.
  • Operating temperature range.
  • Storage temperature range

PBL-mec_case : Casing, ergonomics

Design a housing that meets the needs of the echOpen probe

PBL-mec_case_ergo : Ergonomics, grip

An ergonomic study will be conducted by a designer with the help of practitioners to deduce the ideal format of the probe. Moreover the case must be of an easy cleaning.

PBL-mec_case_mat : Material

Select the material(s) used to make the case according to the following criteria:

  • Ultrasonic Transparency
  • Ease of implementation
  • Strength
  • Bio-compatibility

    PBL-mec_case_dock : Loading Dock

Given the choice of interface of the box with the outside, especially for the loading (wired or induction). The design of a loading dock in which the box will fit will be required. (See: Reloading PBL-mec_nrg_load)

PBL-mec_case_body : Case

Design a case of volume and shape capable of housing the electronic mechanical parts as well as the batteries and the whole wiring.

    PBL-mec_case_body_asm : Assembly Method

Choosing a method for assembling the various parts and shells which allows easy assembly / dismantling with conventional means while meeting the safety standards for a medical device.

List of authors

Aurélie Benoit Vincent

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