Choosing the right configuration for your catheter delivery system testing platform shouldn't be complicated. Yet many R&D engineers are unsure when confronted with variables like tube diameter, stroke length, and steerability options.
Here's the good news: The U-Handle is designed to be reconfigurable. Made a different choice than expected? No problem! swap internal components in minutes and keep testing. This isn't about making a perfect decision upfront; it's about understanding your options so you can start testing immediately.
This guide walks you through the three critical variables (diameter, stroke, steerability), provides specialty-specific recommendations, and gives you a decision framework that works every time. More importantly, we'll show you how the U-Handle's modular design gives you flexibility where it matters most.
Why Configuration Matters, but Doesn't Lock You In ?
Traditional custom catheter handles are permanent, expensive, and inflexible. Change your tube diameter? Build a new handle (€2,000-5,000, 4-6 weeks lead time). Need different stroke length? Start from scratch.
The U-Handle breaks this paradigm.
With modular internal component sets and swappable half-handles, you can:
- Change tube diameters by ordering new component sets and building new catheter assemblies
- Test different stroke configurations by repositioning the carriage
- Add or remove steerability by swapping half-handles
- Iterate your design without completely rebuilding your testing infrastructure
The implication? Your initial configuration choice is a starting point, not a permanent commitment. Focus on getting close to your needs, then refine as you test.
The 3 Critical Variables: Understanding Your Options
The U-Handle offers flexibility across three key dimensions. Let's break down each variable and what it means for your application.
Variable 1: Tube outer diameter (6-24 French)
What it determines: Which catheter shaft sizes your handle can accommodate
Available range: 6Fr to 24Fr for both inner and outer tubes
The 4Fr rule: For optimal push-pull performance, we recommend maintaining a 4 French diameter difference between internal and external tubes. This ensures smooth independent actuation without binding or excessive friction.
Common configurations:
| Application | External Tube | Internal Tube | Diameter Difference |
|---|---|---|---|
| Coronary intervention | 7-8Fr | 3-4Fr | 4Fr |
| Neurovascular | 6-8Fr | 2-4Fr | 4Fr |
| Peripheral vascular | 10-12Fr | 6-8Fr | 4Fr |
| Structural heart (TAVR, Mitral) | 16-24Fr | 12-20Fr | 4Fr |
Understanding diameter reconfiguration:
When you change tube diameters, here's what's involved:
- Order new internal component set for target diameter (€50-150)
- Build new catheter assembly with appropriately sized tubes
- Important: Tubes are bonded to internal components using medical-grade adhesive (see our DIY Catheter Prototyping guide). Once bonded, tubes are typically not reusable when changing diameters—which makes sense, since you're testing a different catheter size
- Install new components in U-Handle frame (20-30 minutes)
Key insight: You're not just changing a setting—you're building and testing a different catheter. But the U-Handle frame, actuation mechanism, and most components remain constant, saving thousands compared to custom handles for each configuration.
The U-Handle's 6-24Fr range covers >95% of catheter-based delivery systems. If your design falls outside this range, contact Protobrix for custom solutions.
Variable 2: Stroke Length (80mm, 100mm, 120mm)
What it determines: The total linear travel available for your internal and external tubes
How it actually works: This is where the U-Handle's design shines. The stroke length (80mm, 100mm, or 120mm) represents the total available travel, but you control where within that range your actuation occurs by positioning the carriage.
The flexible positioning system:
Example 1: 120mm stroke, carriage positioned at the start
- Forward travel: 120mm
- Backward travel: 0mm
- Use case: Pure deployment/advancement (valve delivery, stent release)
Example 2: 120mm stroke, carriage positioned in the middle
- Forward travel: 60mm
- Backward travel: 60mm
- Use case: Bidirectional control (retraction for repositioning + advancement for deployment)
Example 3: 120mm stroke, carriage positioned at the end
- Forward travel: 0mm
- Backward travel: 120mm
- Use case: Pure retraction (sheath pullback applications)
Why this matters: You're not locked into "push only" or "pull only" operation. Position the carriage to match your exact deployment sequence, whether that's:
- 100mm forward deployment
- 40mm retraction + 80mm deployment
- 60mm bidirectional adjustment range
- Any combination that fits within your total stroke
Application-specific stroke recommendations:
80mm stroke:
- Best for: Compact applications with known, short deployment distances
- Typical applications: Coronary stents (15-30mm implants), short peripheral devices
- Flexibility: Position carriage for 80mm push, 80mm pull, or 40mm bidirectional
100mm stroke:
- Best for: Most applications—the versatile middle ground
- Typical applications: Most structural heart valves, standard neurovascular procedures, medium peripheral devices
- Flexibility: Covers 70% of applications with room for bidirectional control
120mm stroke:
- Best for: Long-segment delivery or maximum flexibility
- Typical applications: TAVR (extended sheath advancement), long peripheral stents, complex deployment sequences
- Flexibility: Maximum range—position for 120mm in one direction or split for 60mm bidirectional
Pro tip: When in doubt, choose 100mm or 120mm. The extra range gives you more positional flexibility without penalty. You'll find the optimal carriage position during your first few tests. Adjusting carriage position takes 2 minutes and costs nothing—this is true on-the-fly reconfiguration.
Variable 3: Steerability (Standard vs. Steerable)
What it determines: Whether you have active tip deflection capability
Critical design note: When you select the steerable option, the half-handle controlling steerability manages deflection only, not translation. The other half-handle controls linear push-pull movement.
Standard (Non-Steerable) Configuration:
- What you get: Both half-handles control linear translation (push-pull)
- Includes: Integrated guidewire channel for over-the-wire delivery
- Navigation method: Torque transmission via shaft rotation + guidewire steering
Best for:
- Straight or mildly tortuous anatomy (aorta, IVC, straight peripheral vessels)
- Over-the-wire delivery where guidewire provides navigation
- Procedures with large "landing zones" (e.g., abdominal aortic aneurysm)
- Applications where implant size drives device selection more than steerability
Steerable Configuration:
- What you get: One half-handle controls linear translation, one half-handle controls tip deflection
Deflection options:
- Uni-directional (single pull-wire): Carriage positioned at one end, deflects in one direction only
- Bi-directional (dual pull-wires): Carriage positioned in middle, deflects in two opposing directions
- Deflection range: Up to 180° depending on catheter shaft design and pull-wire setup
- Includes: Guidewire channel remains available
Best for:
- Tortuous vascular anatomy (cerebral vessels, coronary arteries, complex aortic arch)
- Small target zones requiring precise positioning (aneurysms, specific valve locations)
- Procedures where you're navigating without continuous guidewire support
- Testing active catheter maneuverability as a design requirement
Understanding steerable carriage positioning:
Single-cable deflection (uni-directional):
- Position carriage at one end of stroke
- Pull-wire creates deflection in one direction
- Use case: Simple curve requirement (e.g., "bend left 90°")
Dual-cable deflection (bi-directional):
- Position carriage in middle of stroke
- Two pull-wires allow deflection in opposing directions
- Use case: Complex navigation requiring multi-directional tip control
Adding steerability later:
If you start with non-steerable and later decide you need deflection capability:
- You can purchase steerable half-handle separately and swap it in
- Your catheter must be built with pull-wire channels from the beginning
- Pro tip: If steerability is a possibility, integrate pull-wire channels during initial catheter build even if not using them initially—this future-proofs your design
Decision framework:
Does your procedure require navigating: → Sharp vessel curves (>90° turns)? → STEERABLE → Small target access (e.g., specific heart chambers, aneurysm necks)? → STEERABLE → Anatomy where guidewire alone can't provide access? → STEERABLE → Relatively straight paths with guidewire support? → STANDARD (with guidewire channel)
Preparing Your Catheter Tubes: Critical Dimension Planning
Before ordering your U-Handle, you need to understand an important assembly requirement: catheter tubes must be cut to precise lengths that account for the portion mounted inside the handle.
Why Length Matters
The U-Handle isn't just a grip—it's an actuation mechanism. A portion of your catheter tube sits inside the handle mechanism, bonded to internal components. This means:
Total tube length = Working length + Handle mounting length
Example:
- You need 1000mm working length (catheter shaft outside the handle)
- Handle mounting length: 150mm (varies by configuration—see table below)
- Total tube to cut and prepare: 1150mm
Handle Mounting Length Reference
The following table shows how much additional tube length to add for handle mounting:
| Configuration | Outer Tube Mounting Length | Inner Tube Mounting Length |
|---|---|---|
| 80mm stroke, non-steerable | 120mm | 120mm |
| 100mm stroke, non-steerable | 140mm | 140mm |
| 120mm stroke, non-steerable | 160mm | 160mm |
| 80mm stroke, steerable | 120mm | 130mm* |
| 100mm stroke, steerable | 140mm | 150mm* |
| 120mm stroke, steerable | 160mm | 170mm* |
*Steerable configurations require additional length for pull-wire mechanism attachment
Note: These values are approximate and will be finalized in our detailed assembly instructions. Contact contact@protomed.fr for the most current specifications for your specific configuration.
Tube Preparation Workflow
Step 1: Determine your working length
- Measure or calculate the catheter shaft length needed for your application
- Account for anatomy (e.g., femoral access to aortic valve = ~900-1100mm)
- Add safety margin (~50-100mm recommended)
Step 2: Add handle mounting length
- Reference table above for your configuration
Example calculation:
- Working length needed: 1000mm
- Configuration: 100mm stroke, non-steerable
- Mounting length: 140mm (outer), 140mm (inner)
- Cut outer tube to: 1140mm
- Cut inner tube to: 1140mm
Step 3: Cut tubes to final length
- Use sharp tubing cutter (not scissors ! Creates clean, perpendicular cuts)
- Measure twice, cut once
- Deburr cut ends with fine sandpaper
Step 4: Prepare distal end
- Bond distal components (markers, atraumatic tips) to the working length end
- Pro tip: Consider Protobrix threaded atraumatic tips (see below) for maximum flexibility
Step 5: Mount on U-Handle
- Bond tubes to internal components using medical-grade adhesive (Bostik 7452 recommended)
- Insert assembled components into U-Handle frame
- Follow assembly instructions (provided with handle)
Common mistake to avoid: Cutting tubes to only the working length and discovering you can't mount them in the handle. Always add the mounting length from the reference table.
The Threaded Atraumatic Tip: Maximum Flexibility
Most distal components (tips, markers) are permanently bonded to catheter shafts. Once assembled, you can't easily swap tips without destroying the tube.
Protobrix has developed a solution: Threaded radiopaque atraumatic tips
Key Features
- Screw-on/screw-off attachment to catheter shaft
- Radiopaque for fluoroscopy visibility during testing
- Atraumatic design for safe navigation in benchtop models
- Multiple durometer options (Shore 60A, 70A, 80A) for different stiffness levels
- Standard thread interface (typically M2.5 or M3 depending on tube OD)
- Compatibility: Works with tube ODs from 6Fr to 14Fr (contact for larger sizes)
Why This Matters: Real-World Scenarios
Scenario 1: Distal tip optimization without rebuilding entire catheter
- You've assembled a 10Fr/6Fr catheter with complex proximal components, bonded markers at precise locations
- Initial testing shows your soft tip (Shore 60A) compresses excessively during navigation through tortuous path
- Without threaded tips: Rebuild entire catheter with stiffer tip (60-90 min + risk of assembly errors + cost of new tubes)
- With threaded tips: Unscrew soft tip, screw on firmer tip (Shore 80A), resume testing (2 minutes, zero additional tube cost)
Scenario 2: Testing multiple tip geometries
- Your DID requires comparative data on tip performance
- Test sequence: rounded tip → tapered tip → bullet tip
- Without threaded tips: Build 3 complete catheters
- With threaded tips: Build 1 catheter + swap 3 tips (2 min per swap)
- Time savings: ~3 hours of assembly work
Scenario 3: Tube diameter change with tip reuse
- You're changing from 10Fr to 12Fr outer tubes based on pushability test results
- Your threaded tip has compatible thread for both tube sizes
- Benefit: Unscrew tip from old 10Fr tube, screw onto new 12Fr tube
- One less component to source/fabricate when rebuilding catheter
Scenario 4: Disassembly for handle reconfiguration
- You need to change internal component diameter
- Bonded tips prevent you from pulling tubes back through handle
- With threaded tips: Unscrew tip, slide tube out of handle, install new components, slide tube back, re-attach tip
- Enables tube reuse in some scenarios (if bonding to internal components allows careful removal)
Available Options
Durometer (stiffness) options:
- Shore 60A: Very soft, maximum atraumatic behavior, suitable for delicate anatomy models
- Shore 70A: Medium stiffness, good balance of atraumatic design and column strength
- Shore 80A: Firmer, better pushability, suitable for stiffer catheter shafts
Tip geometries:
- Rounded (hemispherical)
- Tapered (cone-shaped)
- Bullet (elongated taper)
- Custom geometries available on request
Thread sizes:
- M2.5 (for 6-8Fr tubes)
- M3 (for 8-14Fr tubes)
- Contact for larger sizes
How to Order
Threaded atraumatic tips are not in our standard online catalog, they're specialized prototyping tools.
Ordering process:
- Email: contact@protomed.fr with subject line "Threaded Atraumatic Tip Order"
Specify:
- Your tube outer diameter (Fr or mm)
- Preferred durometer (Shore 60A, 70A, or 80A)
- Tip geometry (rounded, tapered, bullet, or describe custom)
- Quantity needed
- We confirm: Thread size compatibility and provide quote
- Lead time: Typically 5-7 days
- Cost: €100-200 per tip depending on complexity
Critical Usage Limitation
Benchtop testing only. These threaded tips are prototyping and validation tools designed for:
- ✓ Benchtop navigation testing in silicone models
- ✓ Tortuous path pushability evaluation
- ✓ Ex-vivo testing in tissue phantoms (non-living tissue)
- ✓ Deployment sequence validation
- ✓ Fluoroscopy visibility testing
NOT approved for:
- ✗ Animal studies (in-vivo testing)
- ✗ Clinical trials
- ✗ Regulatory submission as final device configuration
When you progress to animal testing or clinical evaluation, you'll transition to production-grade bonded tips manufactured under full quality control. The threaded tips accelerate your R&D phase, they're not intended as final device components.
Why We Developed This
Tip geometry and stiffness are often the last parameters engineers optimize. Traditional bonded tips mean rebuilding catheters 5-10 times during this optimization phase, at 60-90 minutes and €500+ per rebuild.
Threaded tips reduce this to simple swaps.
The 5-Question Configuration Flowchart
Use this decision tree to identify your optimal starting U-Handle configuration:
Question 1: What is your clinical specialty?
Select the specialty that best matches your device application:
A) Cardiovascular (coronary, TAVR, mitral/tricuspid, LAA closure)
B) Neurovascular (stroke, aneurysm, AVM)
C) Peripheral vascular (PAD, venous, renal/visceral)
D) Other/Custom (complex anatomy, novel applications)
Why this matters: Different specialties have fundamentally different anatomical constraints that drive configuration needs.
Question 2: What is your target vessel/anatomy diameter?
Measure or estimate the diameter of the vessel or chamber where your implant will be deployed:
A) Small vessels (<3mm: coronary, distal neuro, small peripherals)
B) Medium vessels (3-6mm: proximal neuro, mid-size peripherals)
C) Large vessels/chambers (6-12mm: aorta, IVC, heart chambers)
D) Extra-large (>12mm: ascending aorta, large aneurysms)
Why this matters: Vessel diameter determines catheter size, which drives tube diameter selection.
Question 3: What is your maximum deployment/retraction distance?
How much linear travel might you need in either direction?
A) Short (<60mm total)
B) Medium (60-80mm total)
C) Long (>80mm total)
D) Uncertain (exploring multiple scenarios)
Why this matters: Determines stroke length. Remember: you can position the carriage anywhere within the stroke range, so having "extra" range is never a problem.
Question 4: Describe the vascular path to your target:
What does the route from entry point to deployment site look like?
A) Mostly straight (e.g., femoral to abdominal aorta)
B) Moderate tortuosity (e.g., iliac vessels, some cardiac approaches)
C) Highly tortuous (e.g., cerebral circulation, coronary arteries, complex aortic arch anatomy)
Why this matters: Tortuosity combined with guidewire availability determines steerability needs.
Question 5: Will you have guidewire support throughout the procedure?
Can you navigate with a guidewire, or do you need active steering?
A) Full guidewire support (over-the-wire technique)
B) Partial guidewire support (wire removed before deployment)
C) No guidewire (catheter must navigate independently)
D) Testing both scenarios
Why this matters: Guidewire support reduces or eliminates the need for steerable configuration.
Specialty-Specific Recommendations
Based on thousands of procedures and clinical data, here are the most common starting configurations by specialty:
Cardiovascular Applications
Coronary Intervention (PCI, Stents, Balloons)
- Recommended starting config: 8Fr outer / 4Fr inner, 100mm stroke, NON-STEERABLE
- Rationale: Guidewire provides navigation, moderate deployment lengths, guidewire channel included
- Tube length planning: ~1000-1200mm working length + 140mm mounting = 1140-1340mm total
- Tip recommendation: Protobrix threaded tip Shore 70A for testing multiple stiffnesses
TAVR (Transcatheter Aortic Valve Replacement)
- Recommended starting config: 20Fr outer / 16Fr inner, 120mm stroke, NON-STEERABLE
- Rationale: Large bore delivery, extended stroke for flexible carriage positioning during valve deployment
- Tube length planning: ~1100-1200mm working length + 160mm mounting = 1260-1360mm total
- Carriage positioning: Typically start mid-stroke (60mm retract for sheath withdrawal + 60mm advance for fine positioning)
Mitral/Tricuspid Valve Repair (MitraClip, PASCAL, etc.)
- Recommended starting config: 24Fr outer / 20Fr inner, 100-120mm stroke, STEERABLE
- Rationale: Large devices + complex trans-septal navigation requiring precise positioning
- Tube length planning: ~900-1100mm working length + 140-160mm mounting
- Important: Build catheter with pull-wire channels from the start
- Steerable setup: Bi-directional (carriage centered) for multi-plane tip control
Left Atrial Appendage (LAA) Closure (Watchman, Amulet)
- Recommended starting config: 14Fr outer / 10Fr inner, 100mm stroke, STEERABLE recommended
- Rationale: Must navigate to specific LAA ostium location; moderate tortuosity
- Alternative: Start non-steerable if confident in guidewire-based navigation (can add steerable half-handle later if needed)
Neurovascular Applications
Ischemic Stroke Thrombectomy
- Recommended starting config: 8Fr outer / 4Fr inner, 120mm stroke, STEERABLE
- Rationale: Tortuous cerebral vessels, need to reach M1/M2 segments or basilar artery
- Tube length planning: ~1300-1500mm working length + 170mm mounting (steerable) = 1470-1670mm total
- Steerable setup: Typically bi-directional for complex navigation through carotid siphon
- Tip recommendation: Protobrix threaded tip Shore 60A (soft, atraumatic for delicate vessels)
Aneurysm Coiling
- Recommended starting config: 6-8Fr outer / 2-4Fr inner, 100mm stroke, STEERABLE
- Rationale: Microcatheter navigation into aneurysm dome requires active steering
- Tube length planning: ~1400-1600mm + 150mm mounting (steerable) = 1550-1750mm total
- Carriage positioning: Center stroke for bidirectional micro-adjustments
- Tip recommendation: Test multiple tip geometries with threaded tips (rounded vs. tapered)
Flow Diverter/Stent Placement
- Recommended starting config: 8-10Fr outer / 4-6Fr inner, 100mm stroke, STEERABLE
- Rationale: Must achieve precise positioning across aneurysm neck
- Alternative: Some operators prefer guidewire-based navigation—start non-steerable if this is your approach
Peripheral Vascular Applications
Peripheral Artery Disease (PAD) – Femoral/Popliteal
- Recommended starting config: 10Fr outer / 6Fr inner, 120mm stroke, NON-STEERABLE
- Rationale: Moderate vessel sizes, long lesions (drug-coated balloons, long stents), guidewire support
- Tube length planning: ~1100-1400mm working length + 160mm mounting = 1260-1560mm total
- Stroke use: Position carriage for ~100mm forward deployment with 20mm safety margin
Below-The-Knee (BTK) Interventions
- Recommended starting config: 8Fr outer / 4Fr inner, 100mm stroke, consider STEERABLE
- Rationale: Smaller vessels, increased tortuosity below knee
- Decision point: Test with guidewire channel first; upgrade to steerable if navigation proves challenging
- Tube length planning: ~1400-1600mm (long access path)
Venous Interventions (DVT, IVC filters)
- Recommended starting config: 12Fr outer / 8Fr inner, 100mm stroke, NON-STEERABLE
- Rationale: Large diameter veins, relatively straight paths, guidewire support sufficient
- Tube length planning: ~900-1200mm depending on access site
Renal/Visceral Interventions
- Recommended starting config: 8-10Fr outer / 4-6Fr inner, 80-100mm stroke, STEERABLE (for renal)
- Rationale: Renal arteries have sharp take-off angles from aorta requiring active tip deflection
- Tube length planning: ~800-1000mm (shorter access compared to peripheral)
Quick Configurator: Decision Tables
Table 1: Diameter Selection by Application
| Application Type | Outer Tube (Fr) | Inner Tube (Fr) | Working Length (typical) |
|---|---|---|---|
| Small coronary stents | 7-8 | 3-4 | 1000-1200mm |
| Neurovascular (standard) | 6-8 | 2-4 | 1400-1600mm |
| Peripheral angioplasty | 10-12 | 6-8 | 1100-1400mm |
| Structural heart (small) | 14-16 | 10-12 | 900-1100mm |
| TAVR / Large valves | 18-24 | 14-20 | 1100-1300mm |
Table 2: Stroke Length by Total Travel Requirement
| Maximum Travel Needed | Minimum Stroke | Recommended Stroke | Why Extra Range Helps |
|---|---|---|---|
| <60mm | 80mm | 80-100mm | Allows bidirectional positioning |
| 60-80mm | 100mm | 100mm | Optimal flexibility |
| 80-100mm | 120mm | 120mm | Full range + safety margin |
| >100mm or uncertain | 120mm | 120mm | Maximum flexibility |
Remember: Carriage positioning gives you control over direction—more stroke = more options.
Table 3: Steerability Decision Matrix
| Anatomy Type | Guidewire Support | Target Precision | Start With | Future-Proof Strategy |
|---|---|---|---|---|
| Straight path | Full | Low | Non-steerable | No pull-wire channels needed |
| Moderate tortuosity | Full | Low-Medium | Non-steerable | Consider adding pull-wire channels |
| Moderate tortuosity | Partial | High | Steerable | Build with pull-wire channels |
| Highly tortuous | Any | Any | Steerable | Build with pull-wire channels |
| Uncertain | Full | Medium | Non-steerable | Add pull-wire channels as future-proofing |
Understanding What Changes (and What Doesn't)
It's important to understand what's truly reconfigurable vs. what requires rebuilding:
Instantly Adjustable (No Cost, Minutes)
✓ Carriage positioning (changes push vs. pull balance)
- Time: 2 minutes
- Cost: Free
- Frequency: Adjust multiple times per test session if needed
✓ Tip swapping (if using Protobrix threaded tips)
- Time: 2 minutes
- Cost: €10-15 per alternative tip
- Frequency: Test 3-5 tip configurations in one afternoon
Modular Swapping (Low Cost, Hours)
✓ Adding/removing steerability (swap half-handle)
- Time: 10-15 minutes (if catheter has pull-wires already)
- Cost: Steerable half-handle (contact for pricing)
- Limitation: Catheter must be built with pull-wire channels initially
- Frequency: Typically once, when testing proves steerability necessary
Requires New Catheter Build (Moderate Cost, Days)
⚠ Changing tube diameters
- Time: New catheter assembly (1-2 hours) + component swap (20 min)
- Cost: Component set (€50-150) + new tubes (€50-200) = €100-350 total
- Why: Tubes are bonded to internal components; different diameters = different tubes
- Frequency: Typically 1-3 diameter tests during development phase
Key insight: You're not "locked in" to a diameter, but changing it requires building a new catheter assembly—which is appropriate, since you're testing a fundamentally different device configuration.
R&D Kit vs. Single Configuration: The True Value Proposition
Understanding what's truly reusable vs. consumable changes the economics:
Single Configuration (€590):
- You get: One U-Handle with internal components for one diameter configuration
- Best for: Well-defined specifications, limited budget, focused validation
- Expandability: Purchase component sets (€50-150) and build new catheters to test different diameters
Realistic scenario cost when exploring 3 diameters:
- Initial handle: €590
- 2 additional component sets: €200
- 2 additional catheter tube sets: €200-300
- Assembly time: 4-6 hours total
- Total: ~€990-1,090 + time spread over weeks
R&D Kit (€1,590):
You get:
- Complete U-Handle frame
- Internal components for ALL diameters (6-24Fr range)
- Min and max stroke lengths (80mm + 120mm half-handles)
- Steerable components included
- 400+ configuration combinations
- Phone/video support for configuration optimization
- Best for: Exploration phase, uncertain specs, comprehensive Design Input Documents
- Key advantage: All diameter internal components included—build catheters for any diameter within range without ordering new components
Realistic scenario cost when exploring 3 diameters:
- Kit purchase: €1,590
- 3 catheter tube sets: €300-450
- Assembly time: 4-6 hours total (same as single config)
- Total: ~€1,890-2,040
Cost comparison:
- Single Config approach: €990-1,090
- R&D Kit approach: €1,890-2,040
- Difference: €900-950
But the real value isn't just cost—it's time and flexibility:
Time advantage:
- Single Config: Wait 3-5 days for each component set shipment between diameter tests = 2-3 week testing cycle
- R&D Kit: All components on hand = test new diameter same week = continuous testing cycle
Flexibility advantage:
- Single Config: Commit to testing specific diameters upfront
- R&D Kit: "Let's test 10Fr today, 12Fr tomorrow, maybe 14Fr next week based on results" = true agile development
Break-even analysis: If you test 3+ diameters, the R&D Kit's time savings alone justify the cost difference. If you're pre-Series A and demonstrating design rigor to investors, the comprehensive testing capability is invaluable.
Pro tip: Many successful device companies purchase the R&D Kit for their initial development phase, then purchase single configurations for specific team members or validation testing once the optimal diameter is confirmed.
Practical Example: TAVR Project with Realistic Reconfiguration
Let's walk through a realistic development scenario:
Project: Developing next-generation transfemoral TAVR delivery system
Implant: 26mm valve, self-expanding
Anatomy: Femoral access, descending aorta to aortic root
Week 1: Initial Configuration and Build
Configuration selected:
- 20Fr outer / 16Fr inner (based on competitive analysis)
- 120mm stroke
- Non-steerable (aortic anatomy relatively straight)
Tube preparation:
- Working length required: 1100mm
- Mounting length (120mm stroke, non-steerable): 160mm
- Total tube length to cut: 1260mm outer, 1260mm inner
- Source tubes from Protobrix (contact@protomed.fr): €220
Assembly:
- Order Protobrix threaded atraumatic tip (Shore 70A, M3 thread): €12
- Bond markers at appropriate locations
- Bond tubes to internal components (Bostik 7452)
- Thread tip onto distal end
- Mount on U-Handle
- Total assembly time: 2 hours (first build)
Weeks 2-3: Initial Testing Phase
Testing protocol:
- Benchtop navigation through silicone aorta model
- Measure push forces at 10cm increments
- Test deployment sequence (sheath retraction + valve positioning)
- Position carriage at center: 60mm retract capability + 60mm advance
Discovery #1: 16Fr inner tube creates higher friction against 20Fr outer than expected—deployment forces 35% above target
Discovery #2: Shore 70A tip occasionally catches on model's curvatures
Week 4: Iteration 1 - Tip Optimization
Problem: Tip stiffness Solution: Test softer tip
Process:
- Order Protobrix threaded tip Shore 60A: €10
- Unscrew Shore 70A tip
- Screw on Shore 60A tip
- Resume testing
- Time: 2 minutes + 5 days shipping
- Cost: €10
Result: Shore 60A tip navigates model smoothly, no catching. Confirmed optimal tip stiffness.
Week 5: Iteration 2 - Diameter Optimization
Problem: Inner/outer friction too high Decision: Test 18Fr outer / 14Fr inner (maintains 4Fr differential, reduces friction surface area)
Process:
- Order 18Fr/14Fr internal component set: €120 (ships in 3 days)
- Source new tubes (18Fr/14Fr × 1260mm) from Protobrix: €200
Build new catheter:
- Bond markers (reuse same marker positions for consistency)
- Bond tubes to new 18Fr/14Fr components
- Unscrew Shore 60A tip from old 20Fr tube
- Screw Shore 60A tip onto new 18Fr tube ← saves €10 + fabrication time
- Swap old 20Fr/16Fr components for new 18Fr/14Fr components in U-Handle
- Mount new catheter assembly
- Time: 90 minutes (assembly) + 20 minutes (component swap) = 110 minutes
- Cost: €320 (components + tubes, tip reused)
- Timeline: 4 days (3 days component shipping + 1 day assembly)
Result: Push force reduced 28%. Deployment sequence smooth. 18Fr/14Fr confirmed optimal.
Weeks 6-7: Extended Validation
Testing with optimal configuration:
- 100+ deployment cycles
- Multiple aortic anatomy models (straight, moderate angulation, steep angulation)
- Force measurements, deployment timing, valve positioning accuracy
- Video documentation for DID
Discovery #3: In steep angulation model (15% of anatomies), navigation would benefit from slight tip deflection
Week 8: Iteration 3 - Evaluating Steerability
Problem: Edge-case anatomies might benefit from active steering Decision: Test if steerability adds value
Challenge: Catheter not built with pull-wire channels initially Options:
- Rebuild catheter with pull-wire channels + order steerable half-handle (€250 + €200 tubes + 2 hours = significant investment)
- Accept non-steerable limitation and document in DID as anatomical exclusion criteria
Decision: Document anatomical constraints. For 85% of anatomies, non-steerable performs excellently. For next-generation product, incorporate pull-wire channels from Day 1.
Project Outcome: Week 8
Final validated configuration:
- 18Fr outer / 14Fr inner
- 120mm stroke, carriage centered (60mm bidirectional)
- Non-steerable with guidewire support
- Shore 60A threaded atraumatic tip
- Comprehensive DID with 100+ test cycles documented
Total reconfiguration costs:
- Initial assembly: €232 (tubes + tip)
- Tip swap: €10
- Diameter change: €320 (components + tubes, tip reused)
- Total project cost: €562 + initial U-Handle (€590 for single config or €1,590 for R&D Kit)
Total time from start to validated configuration: 8 weeks
Key savings from U-Handle modularity:
- Threaded tip saved 2 iterations (€20 + ~1 hour assembly time)
- Carriage repositioning tested 5+ deployment sequences with zero reconfiguration cost
- Without modular system: would need 3 custom handles (€6,000-12,000, 12+ weeks lead time)
Custom U-Handle: When Standard Options Aren't Enough
Some applications require features beyond the standard U-Handle platform:
Custom options available (from €2,500):
- Additional lumens: Flush ports, pressure monitoring channels, drug delivery pathways
- Sealed/flush design: Hermetic sealing for specific testing environments
- Hemostatic valves: Integrated Touhy-Borst or similar for simulating blood backflow prevention
- Custom actuation mechanisms: Application-specific deployment sequences
- Integrated sensors: Force measurement, position tracking, deployment timing
- Ergonomic modifications: Handle shaping for specific user preferences or robotic interfaces
Process:
Book engineering call: 30-minute consultation with Protobrix engineer (free)
- Email contact@protomed.fr with subject "Custom U-Handle Consultation"
- Describe your application and specific requirements
- Feasibility assessment: We evaluate requirements and confirm technical viability
- Receive quote: Detailed pricing based on complexity (typically €2,500-6,000)
- 14-day development: Custom U-Handle built on our proven platform
- Validation support: We help verify custom features meet your testing needs
When to consider custom:
- Your application requires multi-lumen fluid management (contrast injection, saline flush, drug infusion)
- You're simulating specific clinical workflow elements (hemostasis testing, pressure monitoring)
- Your delivery system has unique deployment mechanisms not covered by standard push-pull
- You need features to match a predicate device for regulatory comparability testing
Tubes and Components: What You Need to Source
The U-Handle is the actuation platform. You provide the catheter components:
Components you source:
- Catheter tubes (inner and outer shafts, cut to proper length including mounting allowance)
- Distal components (markers, tips—or use Protobrix threaded tips)
- Proximal components (luers, connectors if not integrated into handle)
- Medical-grade adhesive (Bostik 7452, 7475, UV1540, 2720 recommended)
Protobrix Tube Supply Service
Through partnerships with AP Technologies and SG Medical, Protobrix maintains inventory of commonly used catheter tubing:
Available materials:
- Pebax (various durometers: 40D, 55D, 63D, 72D)
- Braided and non-braided reinforcements
- PTFE liners (single and multi-lumen)
- Polyurethane shafts
- Coil-reinforced options
Advantages of sourcing through Protobrix:
- Speed: Ships within 2-3 days vs. 4-6 weeks from traditional suppliers
- Compatibility guaranteed: We know exactly which tubes fit which U-Handle configurations
- Small quantities: No 100-meter minimum orders—buy what you need for prototyping
- Pre-cut service available: Provide your total length (working + mounting) and we cut to spec
- Expert guidance: Our engineers help select optimal tube specifications for your application
How to order tubes:
Email contact@protomed.fr with:
- Desired outer and inner diameters (French or mm)
- Material preference (Pebax, PTFE, Polyurethane)
- Reinforcement type (braided, coiled, or plain)
- Total length needed (including mounting length—see reference table)
- Application context (we can recommend optimal specs)
- Quantity
Typical response time: Quote within 24 hours, shipping within 2-3 days
After Configuration: Getting Started with Your U-Handle
Once you've selected your starting configuration and prepared your catheters:
Day 1: Unboxing and Initial Setup
- Review included assembly instructions
- Familiarize yourself with carriage positioning system
- Understand which half-handle controls what (if steerable: one for translation, one for deflection)
- Verify guidewire channel access
- Reference tube mounting length table for your configuration
Day 2: Catheter Preparation
- Calculate total tube length (working length + mounting length)
- Cut tubes to specification
- Assemble distal end (bond markers, attach threaded tip)
- Bond tubes to internal components using Bostik adhesives
- Allow cure time (follow adhesive manufacturer specifications)
Day 3: First Mount
- Install assembled components in U-Handle frame
- Position carriage for anticipated deployment sequence
- Perform dry-run actuation (no load) to verify smooth motion
- Document baseline setup with photos for DID
Week 1: Baseline Testing
- Simple straight-path pushability testing
- Document baseline forces and deployment feel
- Verify carriage positioning meets deployment needs
- Identify any binding or friction points
- Video record for documentation
Weeks 2-4: Iterative Optimization
- Test in progressively complex models (tortuous paths, anatomical phantoms)
- If using threaded tips: swap tip stiffnesses and geometries, document comparative performance
- Adjust carriage positioning to optimize deployment sequence timing
- Build performance comparison matrices for DID
Weeks 5-8: Validation and DID Building
- If diameter changes needed: order component sets, build new catheters, compare configurations
- If steerability needed: evaluate if benefit justifies rebuilding with pull-wire channels
- Run validation test protocols (100+ cycles recommended)
- Generate quantitative performance data
- Document optimal configuration with complete specifications
The advantage: Continuous testing with optimization refinements, not stop-and-wait cycles for new hardware.
Frequently Asked Questions
Q: What if I choose the wrong diameter initially?
A: You can test a different diameter by ordering internal component sets (€50-150) and building a new catheter with appropriately sized tubes. This is expected during development—you're validating optimal specifications, not guessing perfectly on day one.
Q: Do I lose my tubes when changing diameters?
A: Yes, tubes are bonded to internal components and typically aren't reusable when changing configurations. However, if using Protobrix threaded atraumatic tips, you can unscrew and reuse tips on new catheters—saving time and cost.
Q: How do I know what length to cut my tubes?
A: Use the Handle Mounting Length Reference Table in this guide. Add the mounting length for your configuration to your required working length. For example: 1000mm working + 140mm mounting (100mm stroke, non-steerable) = 1140mm total tube length.
Q: Can I test multiple configurations without buying the R&D Kit?
A: Yes. Start with a single configuration, then purchase component sets as testing reveals the need for different diameters. The R&D Kit is more economical if you know upfront you'll test 3+ diameter configurations, but it's not required.
Q: How do I know if I need steerable or non-steerable?
A: If you have full guidewire support and relatively straight anatomy, start non-steerable (includes guidewire channel). Only select steerable if your anatomy is highly tortuous or you're navigating without continuous guidewire support. Pro tip: If there's any chance you'll need steerability, build your catheter with pull-wire channels from the start—this allows you to add a steerable half-handle later without rebuilding the catheter.
Q: What are Protobrix threaded atraumatic tips and why should I use them?
A: They're screw-on/screw-off radiopaque tips available in multiple stiffnesses (Shore 60A, 70A, 80A) and geometries. They allow you to swap tip configurations in 2 minutes without rebuilding your entire catheter. Critical for: tip optimization phase of development. Limitation: Benchtop testing only, not for animal studies.
Q: Can I order tubes from Protobrix?
A: Yes. We maintain stock through partnerships with AP Technologies and SG Medical. Email contact@protomed.fr with your specifications. We often ship within 2-3 days and can pre-cut to your specified total length (working + mounting).
Q: What if my application needs custom features like additional lumens?
A: Book a free 30-minute engineering consultation: contact@protomed.fr with subject "Custom U-Handle Consultation". We'll assess feasibility and provide a quote (typically €2,500-6,000, 14-day build time).
Q: How does carriage positioning work?
A: You position the carriage anywhere within the total stroke (80mm, 100mm, or 120mm). Position at start = full forward travel. Position at end = full backward travel. Position in middle = bidirectional travel. Adjust based on your deployment sequence needs. This adjustment takes 2 minutes and is completely free.
Q: Does the steerable option replace one of the push-pull controls?
A: Yes. With steerable configuration, one half-handle controls linear translation (push-pull), the other controls tip deflection. You repurpose one control axis for steering instead of redundant push-pull.
How to Order: Your Configuration Checklist
Ready to configure your U-Handle? Use this checklist:
☐ Outer tube diameter: _____Fr (6-24Fr range)
☐ Inner tube diameter: _____Fr (recommended 4Fr smaller than outer)
☐ Calculate total tube lengths needed:
- Working length: _____mm
- Mounting length (see reference table): _____mm
- Total tube length to prepare: _____mm
☐ Stroke length: ☐ 80mm ☐ 100mm ☐ 120mm
☐ Steerability: ☐ Standard (non-steerable, includes guidewire channel) ☐ Steerable - If steerable or potentially steerable: ☐ Build catheter with pull-wire channels
☐ Distal tip: ☐ Traditional bonded tip ☐ Protobrix threaded tip (email to order)
☐ Catheter tubes: ☐ Sourcing separately ☐ Order from Protobrix (email contact@protomed.fr)
☐ Uncertain about optimal config? ☐ Consider R&D Kit for maximum flexibility
Optional: ☐ R&D Kit (all diameter components included, 400+ combinations)
☐ Additional internal component sets (for diameter testing)
☐ Multiple threaded tips (for tip optimization testing)
☐ Custom features (book engineering consultation)
Remember: Your initial configuration is a starting point. The modular design allows refinement as you test.
Download: Configuration Decision Tool
The Configuration Decision Tool includes:
- ✓ Interactive 5-question flowchart (digital PDF)
- ✓ Specialty-specific quick-reference tables
- ✓ Tube length calculator with mounting allowances
- ✓ Diameter/stroke/steerability decision matrices
- ✓ Cost calculator: single config vs. R&D Kit vs. component sets
- ✓ Carriage positioning guide for different deployment sequences
- ✓ Tube sourcing guide with Protobrix partners
- ✓ Threaded tip selection guide
This tool walks you through configuration selection, tube length calculation, and shows you optimization paths as your testing evolves.
Download the Configuration Decision Tool →
Conclusion: Start Testing, Optimize as You Learn
The U-Handle's modular design changes the configuration decision from a permanent commitment to a starting point with clear optimization paths.
The philosophy:
- Choose a reasonable starting configuration based on your current understanding (use the 5-question framework)
- Prepare catheters with proper tube lengths (working length + mounting length from reference table)
- Start testing immediately—don't delay for "perfect" specs
Optimize as you learn:
- Swap tips in minutes (if using threaded tips)
- Adjust carriage positioning instantly
- Change diameters when testing reveals better options (new components + new catheter build)
- Build comprehensive validation data for your Design Input Document
Your initial configuration should be:
- ✓ Close to your application's needs (use specialty recommendations)
- ✓ Properly dimensioned (include mounting lengths in tube calculations)
- ✓ Selected quickly (don't overthink—optimize through testing)
- ✓ Future-proofed if uncertain (build with pull-wire channels even if starting non-steerable)
What it doesn't need to be:
- ✗ Perfect (perfection comes through iteration)
- ✗ Final (modularity enables optimization)
- ✗ Comprehensive (test one config first, then expand)
Most importantly: Get your U-Handle, prepare your catheters with proper lengths, mount them, and start generating data. Configuration optimization happens through testing, not analysis paralysis.
The U-Handle's modularity means the question isn't "what's the perfect configuration?"—it's "which configuration gets me testing fastest, with clear paths to optimize as I learn?"
Ready to start testing?
📧 Email: contact@protomed.fr
🛒 Shop: protobrix.fr/shop
📞 Phone: +33 367 176 721
Questions about your specific application?
Book a free configuration consultation with our engineering team. We'll walk through your application, help calculate proper tube lengths, and recommend the optimal starting setup.
Protobrix U-Handle: The modular testing platform trusted by medtech innovators worldwide. From concept to confidence in weeks, not months.
