# [Mechanics of Solid] Friction on a needle inserted in tissue

• Prathmesh Deshmukh
In summary, the conversation discusses the forces on a needle being inserted into tissue. It is mentioned that the needle experiences friction from the needle-tissue interaction and that the pressure from the surrounding tissue grips the needle. The question is raised about how to determine the pressure from the tissue, and the formula of Pressure * Volume = Force * h (h is length of penetration) is suggested to calculate the friction force. Further discussion includes using the deformation or young's modulus of the tissue to find the pressure exerted by the tissue on the needle.
Prathmesh Deshmukh
Hello ,
I'm trying to model the forces on a needle being inserted in a tissue. Needle tip penetrates the tissue surface and as it moves through the tissue, it experiences friction from needle-tissue interaction. Friction arises from the pressure exerted by surrounding tissue as it grips the needle. Assuming we have all the properties data for the tissue material, needle dimensions etc, how can we determine the pressure from the tissue ? [for friction force calculation]

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U can use the formula Pressure * Volume equals Force*h(h is length of penetration)

Parixit said:
U can use the formula Pressure * Volume equals Force*h(h is length of penetration)
That's true. But how would you calculate the pressure exerted by tissue on needle? I'm sure that we have to use the deformation / young's modulus or some another property of the tissue to find the pressure.

## 1. How does the friction between a needle and tissue affect the insertion process?

The friction between a needle and tissue plays a crucial role in the insertion process. If the friction is too high, it may cause damage to the tissue and make the needle difficult to insert. On the other hand, if the friction is too low, the needle may not be able to penetrate the tissue at all.

## 2. What factors can influence the amount of friction between a needle and tissue?

The amount of friction between a needle and tissue can be influenced by several factors, including the sharpness and size of the needle, the type of tissue, and the speed and angle of insertion. Additionally, the presence of any lubricants or bodily fluids can also affect the amount of friction.

## 3. How is the coefficient of friction calculated for a needle inserted in tissue?

The coefficient of friction is a measure of the amount of friction between two surfaces. It can be calculated by dividing the force required to insert the needle by the weight of the needle. This can be done by inserting the needle into different types of tissue and measuring the amount of force needed to penetrate each one.

## 4. Is there a recommended amount of friction for needle insertion in tissue?

There is no specific recommended amount of friction for needle insertion in tissue as it can vary depending on the type of tissue and the specific procedure being performed. However, it is important to find a balance between too much and too little friction to ensure the needle can be inserted smoothly and without causing damage to the tissue.

## 5. How can friction between a needle and tissue be reduced?

There are a few ways that friction between a needle and tissue can be reduced. One method is to use a lubricant, such as medical-grade silicone or mineral oil, which can help the needle glide more easily through the tissue. Another approach is to reduce the angle and speed of insertion, as these factors can also affect the amount of friction. Additionally, using a sharper and smaller needle can also help to reduce the amount of friction during insertion.

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