Catheter Stylet

The word stylet can have a variety of meanings. In medicine it can mean a wire run through a catheter or cannula to render it stiff or to remove debris from its lumen. A catheter stylet is run through a catheter for stiffness or to remove debris. Some doctors will also interchange the term guide wire with stylet.

Catheter Introducer

A catheter stylet used as a catheter introducer would more commonly be called a guide wire than a stylet. A catheter introducer can be ground to a taper to allow the introducer to more easily enter a vessel prior to a catheter.

Catheter Flexibility

Designed to assist in the insertion of catheters and drains when indicated. They are typically made of stainless steel and feature a locking handle that holds the catheter taut during insertion.

Catheter Stylet Stop

An item consisting of a metallic collar with a setscrew which may be tightened against the shaft of a STYLET, CATHETER at a desired position to prevent introduction of the stylet beyond such position.

Stylet Manufacturing

No matter what you call a stylet, Modern Grinding can make them. Please contact us for help with your next project.

Bipolar Electrode

Bipolar electrochemistry is a phenomenon in electrochemistry based on the polarization of conducting objects in electric fields. Indeed, this polarization generates a potential difference between the two extremities of the substrate that is equal to the electric field value multiplied by the size of the object. – Wikipedia

Modern Grinding is a custom contract manufacturer of bipolar electrode monitoring assemblies. We have a manufacturing facility and clean room assembly facilities capable of fabricating wires with the currents that electrode product designers need.

Electrode Testing

Modern Grinding works with customers to develop and design bipolar electrode assembly testing boards. We 100% test electrode assemblies prior to shipping.

Electrode Monitoring

An electrode in an ECG monitoring device can be used for long term patient monitoring. Modern Grinding uses the highest level of quality systems to ensure our customers devices succeed over the long term.

What is a Guidewire

The terms guidewire and catheter are often interchanged by non-technical professionals, we wanted to provide a simple description of what a guidewire is and how it works.

Guidewires are used to guide catheter products to a desired treatment location within the body. They are typically inserted into patients through a small incision in the groin and then maneuvered through arteries and vessels to the area of vascular disease.

Single Use

Once in place, the catheter is threaded over the guidewire for treatment. The introducer wire is then pulled out of the system and disposed of.

Minimally Invasive

Guidewires are considered minimally invasive since it only takes a small incision to get the wire into the system. Compared to alternative options, the guide wire is much less invasive. Improvements in imaging and sensor technologies allows the guidewire to be placed much more accurately.

Other Uses of the Term

Some people may call a K-Wire a guidewire which is technically correct but not the common usage. In Spinal surgery, the k-wire is used to penetrate bone in a precise spot. After the k-wire is firmly in place, a cannulated screw is placed over the K-wire and screwed into place. After the screw is firmly placed, the k-wire is taken out.

Exchange Guidewires

At Modern Grinding, we often here about exchange guidewires, exchange wires, guidewire exchange catheters and rapid exchange guidewires and we wanted to do some explaining about what it is and why it is used.

A guidewire is typically used to find a specific spot internally though a minimally invasive process. A guidewire is introduced through the skin and then identified in the body through some form of imaging or sensing of body location. Once the correct spot is found internally, this location is marked and the the introducing guidewire is pulled out through a catheter. A new guidewire is then put into the body to perform a certain function. The new guidewire may have a stent or may perform coil embolization or some function like these. The use of separate guidewires is what necessitates the exchange of wires.

Modern Grinding has the capabilities to manufacture a wide variety of guidewires in house, please contact us for details.

This information comes from a non-medical professional and is intended to demystify this process for a non-technical audience, not provide medical advice. If you find information about exchange guidewires above to be incorrect, please correct us –


Stainless Steel Electropolishing – Medical Device Components

Modern Grinding just added an electropolishing machine (We call her Electroid) to our small but growing family of advanced wire and pin fabrication machinery. For those who are unfamiliar, electropolishing is a subtractive process (material is taken off) which leaves metal with a shiny property, similar to that of chrome. Our machine is mainly used for stainless steel electropolishing of medical device components. We adhere to ASTM B912 electropolishing standard.

What does this mean for our customers? Firstly it means that we can give you electropolishing at a much more affordable rate. Secondly, we can provide a much faster turnaround on electropolished parts since we don’t need to ship parts to a secondary facility. We have dedicated staff who can turnaround wires in a few hours if need be. We consider anything under 200 parts to be small batch. We don’t have fixturing for larger batches. If need be we could electropolish medium and large batches but it might be cost prohibitive over larger electropolishing companies.

We can change settings to determine how much material is taken off during electropolishing. We can hold .0002 in diameter change from the eletctropolishing. Again, it is a subtractive process so material is lost during the process. Some types of products we have eletropolished include K-Wires, Steinmann Pins and a variety of pin, wire and screw products.

501(K) Spinal Device Approvals

Congratulations to companies who received 510(K) approval this November. Modern Grinding is going to try and list smaller companies who receive approval for spine devices on a monthly basis as a means to provide a view into the newest and latest products on the market:

Company/Product Description: If you have neck or back pain, you’ve come to the right place. Our Physical Therapists are experts in diagnosing and rehabilitating spinal injuries. We specialize in pre and post surgical rehabilitation, neck and back injuries, and chronic pain.

Company: Integrity Spine
Company/Product Description: Integrity Spine is a medical device company focused on advancing the products and technologies used in spinal procedures.

Company: Seaspine, Inc.
Company/Product Description:

Integra LifeSciences, a world leader in medical technology, is dedicated to limiting uncertainty for surgeons, so they can concentrate on providing the best patient care. Integra offers innovative solutions in orthopedic extremity surgery, neurosurgery, spine surgery, and reconstructive and general surgery.

Integra’s orthopedic products include devices and implants for spine, foot and ankle, hand and wrist, shoulder and elbow, tendon and peripheral nerve protection and repair, and wound repair. Integra is a leader in neurosurgery, offering a broad portfolio of implants, devices, instruments and systems used in neurosurgery, neuromonitoring, neurotrauma, and related critical care. In the United States, Integra is a leading provider of surgical instruments to hospitals, surgery centers and alternate care sites, including physician and dental offices.

Company/Product Description: The APEX Spine System is comprised of implants and instruments for stabilization of the spine during fusion in the thoracic, lumbar and sacral regions.

Company/Product Description: We combine the experience of surgeons with the ingenuity of engineers to design and develop devices and instruments for spinal fusion and less exposure surgery (LES). Our founding surgeons are involved in every step of the product development cycle, collaborating with our innovation team to create intelligent solutions.

Company/Product Description: The ZIP features articulating bone anchors, a one-step locking mechanism with no set screw and a large graft space designed for biologic material. It is designed for stabilization during T1-S1 lumbar fusion procedures, specifically for the treatment of degenerative disc disease, spondylolisthesis, spinal tumors and trauma. The ZIP is available in various sizes to accommodate different patient anatomy.

Company/Product Description: NLT SPINE specializes in the development of innovative spine surgery instrumentation and implants for treating degenerative spinal conditions through small surgical incisions. The company’s vision is to improve patient care and reduce total treatment costs by ultimately shifting from traditional open surgical routines to MISS, employing new methods and technologies to enhance usability and outcomes.

Led by top international leaders in spinal surgery, NLT SPINE holds a wide portfolio of pending and issued patents that cover the non-linear core technology and related implant and instrument technologies.

Company/Product Description: Marketed for the treatment of spinal pathologies (scoliosis, spondylolythesis, traum..) , the PASS LP® thoraco-lumbar fixation system allows to connect the rod at distance from the spine and to perform a 3D correction through progressive stress distribution on all anchorages thanks to the ST2R technique (Simultaneous Translation on 2 Rods).

Company/Product Description:  The ANAX 5.5 Spinal System is a top-loading multiple component, posterior spinal fixation system which consist of pedicle screws, rods, set screws, connectors, and a transverse (cross) linking mechanism. The ANAX 5.5 Spinal System allows surgeons to build a spinal implant construct to stabilize and promote spinal fusion.

– Top loading for easy introduction of 5.5 mm diameter rod
– A low-profile polyaxial screw head
– Rounded screw head allowing up to 65degrees of angulation
– Double-lead threaded screw for its fast insertion
– No complication but efficiency self tap of the screw
– No cross threading of the set screw
– Rod available in titanium and cobalt chromium (CoCr)

Company/Product Description:  CoreLink designs and manufactures precision surgical instruments and implants with a single goal: to deliver the highest quality products to enable surgeons to provide the best possible outcomes.

Nitinol Grinding and Nitinol Medical Device Design Considerations

We do a lot of nitinol projects here at Modern Grinding. If there is one material which keeps me up at night and gives me grey hairs, it is grinding nitinol. The biggest difficulty is the abrasive nature of nitinol. It can kill a standard grinding wheel in a single pass. We recently had a part which was one inch long and .024″ in diameter and it ended up taking us an entire day to complete 7 pieces in spec.

If you are building a medical device using nitinol here are some considerations that you should make.

Outside Diameter Vs. Minor Diameter
In order to grind nitinol, we start with a single wire and grind away material. If your outer diameter is .125″ and your minor diameter is .050″, your manufacturer is going to be in a world of hurt. Removing that amount of material is going to hurt any profile that is dressed into the grinding wheel. If you have a large difference between your outside diameter and your inner diameter, and if there are secondary ways to fabricate the wire after grinding the wire look into these while also talking to your grinder.

If you have room to increase your thread diameter tolerance, let the manufacturer know this. The most difficult dimension to keep is going to be your minor diameter of your thread.

Standard Nitinol Sizes
Nitinol is much more expensive than stainless steel. Commonly wire manufacturers won’t stock uncommon nitinol sizes. Check with your manufacturer if they have a size close to what you have designed if you have room to play with on your wire. This comes into play during nitinol prototype phase. If you need small quantities of an off size wire it can be costly. The manufacturer will need to order raw materials and the minimum purchase cost may be a lot more wire than your product requires

Not trying to scare anyone, we welcome any and all nitinol grinding challenges and we will try to provide the most competitive pricing on any and all projects.

Minimally Invasive Solutions and MIS K-Wires

Modern Grinding attended the North American Spine Surgery annual convention in New Orleans and learned a lot about how our Nitinol K-Wires are used in surgery. We manufacture K-Wires for over 20 spine medical device companies who were displaying at the convention. Prior to attending the convention, I was under the impression that the K-Wires we manufacture were used as an implanted fixation device in the spine. I was wrong.

In the spinal medical device community, Modern Grinding K-Wires are used as “guidewires” in MIS fusion systems. The doctors use nitinol wires because they are flexible, strong, and small such that they are easy to navigate to the bone which is being operated on. After the K-Wire is guided to the correct location. A cancellous screw or cannulated screw is placed over the k-wire and screwed into the bone and a plate. Once screwed into place, the K-wire is removed and the screw is implanted for longer term use. In minimally invasive surgery, less of a footprint is opened up for surgery.

One medical device R&D researcher asked me how many of our nitinol K-Wires have threads and why device designers use thread in K-Wires as apposed to just having a product they could hammer into the bone. I can’t really answer that, I am not the designer. About 80% of our nitinol K-Wires have threads vs. a much smaller percentage of our Stainless Steel wires have threads. My guess is that the thread enables the K-Wire to maintain a stronger hold in the bone while the screw is placed over it.

We really enjoyed the convention and all of the companies we had a chance to speak with. If you are a MIS spine fusion researcher or engineer don’t hesitate to contact us with questions about our nitinol K-Wires. We are getting more and more requests and consider ourselves to be one of the leaders in this field. We look forward to helping with your next project!

Trocar Tip Angle Grinding (Troubleshooting)

We are currently in the middle of a medical device project which involves grinding a standard 15 degree trocar tip on 1.1mm stainless steel wire (316LVM) K-wire. We are having issues with a burr along one edge of the trocar tip. We noticed this burr early on and we have been troubleshooting it. I wanted to make this post in case it could help other manufacturers who are troubleshooting grinding problems.

The standard trocar tip angle we see is 15 degrees. The 15 degrees is measured from the angle of one face of the tip against the center line of the wire.  We have done 8 degree angles for sharper tools and 45 degree angles for a less sharp tools. If you are looking at the end of the wire, the trocar tip is divided into 3 – 120 degree angles. 

The Program
We set up our program to start by grinding off the tip. We grind off about .005″ of material at the edge of the wire. We can only do this on projects in which the wire is larger than the final product and we have excess material that we can waste. Having excess material also allows us to use a sensor for automatically loading the wire. If we don’t have any access wire to use, it is difficult to use the sensor because the leading tip may not be precise.

One Pass at the Tip
We started out our grinding program just taking one pass at the tip i.e. grinding all three tips of the trocar in a single pass along the grinding wheel. This is when we first noticed the burr. We have done grinds in the past and only done a single pass and we had no problems.
Verdict: Did not work

Where does the burr come from?
The edge burr is coming from stainless steel material getting pushed to the side during the grind process and having no where to go. It pushes out over the angle of and offset trocar angle.

Slow down the Grind
For the next attempt, we tried to slow down the grind. We kept with a single pass. Our hope was that by slowing down the grind it would give the material more time to be ground away instead of getting pushed aside.
Verdict: Did not work

Two passes at the Tip
For the next attempt, we kept the grind slowed down and we added a second run across each face of the trocar tip. Our hope was that the second run across the tips would help clear away the burr from the first grind.
Verdict: Helped a little, but did not work

Three passes at the Tip
For the next attempt, we kept the grind slowed down and we added a third run across each face of the trocar tip. Our hope was that the second run across the tips would help clear away the burr from the first grind.
Verdict: Helped a little more, byt did not work

Redressing the Wheel
We are using the wheel dress from a previous project which has a radius dressed into the wheel. The plan is to create a dress a square coming out of the wheel, do you think this will help? We will let you know. We have one more project which needs the radius and then we will try it out

If you are having difficulties with a grinding project, don’t hesitate to reach out. It is what we do all day long. Our engineers are available to help.


Medical BioMEMS & MEMS Fabrication

As a continuation to our previous post, we wanted to elaborate on some of the exciting systems we are developing for clients in the medical industry. MEMS stands for microelectromechanical system. Motion, pressure, and flow sensors are providing advanced functionality to a multitude of medical applications.

Modern Grinding comes into play since many researchers use our wires to correctly place MEMS in the body. In addition to using our wires for placement, wires can be used as a means to send a signal to the MEMS or receive a signal from the MEMS. By minimizing power consumption, enhancing precision, and allowing for more-intelligent devices, MEMS inertial sensing has moved to the forefront of medical device enabling technologies in recent years.

Outside of the body, the wire connects to a small pcb board which receives or sends the signals across different wires. This enables a medical clinician to read results and move the MEMS or correctly diagnose.

Modern Grinding has the capability to make wire forms which connect to MEMS and allow them to travel through narrow passage ways. Some of our sensors have been enclosed inside of coils with radiopaque markers.  Modern Grinding also has the ability to connect this wire to an external PCB board. It’s actually a fairly simple process, if you have the right equipment.

Some of the MEMS we have seen include cardio MEMS, pressure MEMS, flow MEMS, vibrating MEMS, antenna MEMS, photonic sensors and barometer MEMs.