June, 23, 2020

Towards Waterjet Steerable Needles

This paper measured the waterjet needle’s insertion forces and compared them with a traditional needle with no waterjet running through.

It is shown that incorporating a waterjet reduces the insertion force and thus buckling of the needle.

The contributors for this project are Mahdieh Babaiasl, and Fan Yang under the supervision of Dr. John P. Swensen.

Abstract of the Paper Towards Waterjet Steerable Needles

Water-jet technology has been used extensively for decades industrially for many applications including mining, plastic, metal, stone, wood, and produce cutting.  
The use of water-jet in medical applications has been developed more recently and it is used for different applications such as soft tissue resection, bone cutting, wound debridement, and surgery.  
In this paper, a new application of water-jet technology in the medical field is proposed, namely water-jet cutting at the tip of a needle with a long-term goal of steerable needles.  
A needle insertion system is designed and built, which has a custom-designed water-jet nozzle attached to a Nitinol needle as its ”needle”.  
Insertions with and without water-jet into 10%, 15%, and 20% Poly (styrene-b-ethylene-co-butylene-b-styrene) triblock copolymer (SEBS) tissue-mimicking simulants are performed and the associated force data is measured using a force sensor at the base of the needle.  
The results of force vs. displacement show that the water-jet reduces the insertion force associated with traditional needles by eliminating tip forces.  
In this paper, a custom-designed straight nozzle is used to show the feasibility of water-jet steerable needles, whereas future work will focus on steerability using steerable nozzles.  
Depth of cut as a function of fluid velocity is also measured for different volumetric flow rates.  
The results show that the depth of cut is a linear function of fluid velocity when the width of the water-jet nozzle is sufficiently small and smooth.

Schematic of forces acting on the needle passing through the tissue for (a) the no water-jet case with a traditional needle and (b) using water-jet cutting. (c) In the case of waterjet (blue schematic), the tip forces are eliminated, and only friction along the shaft of the needle exists (it is even expected to be lower than friction due to lubrication provided by water).

You can see the full article on waterjet needles HERE!

The experimental force data along with codes to run the data are uploaded to Mendeley Data in order for other researchers to use them for their own research purposes is available at:

The Software related to needle insertion controller implemented in C and Python can be downloaded below: