Investigation of vibration parameters for needle insertion force reduction

Many medical interventions in therapy and diagnostics require needle insertion into tissue. Common complications such as increased pain and formation of haematoma are caused by wrong needle positioning. It has been shown that pain experience and needle positioning can be improved by a reduction of insertion force, which can be achieved by vibrating the needle axially. An experimental setup has been designed to investigate the influences of different combinations of vibration frequencies (10, 100, and 200 Hz) and vibration amplitudes (20, 100, and 500 μm) during needle insertion into thin sheets of polyethylene terephthalate (PET). A customary 20 W loudspeaker was used to generate the vibration. The results indicate a maximum reduction of 73 % in puncture force and up to a 100 % reduction in shaft friction force. However, the additional vibration force generated by the vibration movement has to be high enough to generate positive effects in terms of force reduction.

Incremental Needle Insertion System for Force and Position Sensing

An Incremental Needle Insertion System (INIS) which simultaneously measures the force and position of a needle during insertion was designed and fabricated for use in a tissue deformation study to improve realism in medical simulation. The INIS was tested in a fresh frozen cadaver experiment and the position of the needle was plotted and compared to the expected needle path. It was found that the INIS is sufficiently accurate with an average path deviation of 1.55 mm. In addition, INIS was shown to successfully measure the maximum Central Venous Catheterization needle insertion force which ranged from 3.02 N to 3.73 N.

Modeling of geometry and insertion force of a new lancet medical needle

Lancet needle is a typical medical treatment device. Its tip consists of two lancet planes and one bevel plane. When the lancet needle is inserted into soft organ tissue, the insertion force may influence the needle cutting direction and treatment effect and increase the pain. One of the main factors affecting this insertion force is the geometry of the needle tip. Based on the research on the shape and processing method of the conventional lancet needle, a new lancet needle tip geometry was obtained by adjusting the relative position of the grinding wheel to the needle. A mathematical model of this new lancet needle was established. The relationship between processing parameters and needle shape was analyzed, and the needle insertion force was predicted. Compared with the conventional lancet needle, the new lancet needle is sharper, and the insertion force on the cutting edge is smaller. However, this change in the grinding position of the needle lancet plane has a great influence on the shape of needle tip near the intersection of the bevel plane and the lancet plane. Some special second bevel angle and rotated angle will cause a large change in the specific force at the intersection place, which is not conducive to reducing the insertion force.

Measurement of Syringe Needle Forces for a Haptic Robotic Training Device

Medical simulation plays a critical role in the training of surgical and medical residents. Training simulators give residents an environment to practice a wide variety of procedures where they can learn and make mistakes without harming a living patient [1]. In recent years, much research has been conducted on applying haptic or force feedback technology to surgical simulators in order to create more effective training devices [2]. Simulators such as the LapSim (laparoscopic simulator) and the PalpSim (palpitation needle insertion simulator) have both utilized haptic feedback arms to provide the physical sensation of performing surgical procedures to the user [3, 4]. The haptic simulator shown in Fig. 1 is currently in development. This virtual reality haptic robotic simulator for central venous catheterization (CVC) utilizes a haptic feedback arm to provide the feeling of a syringe being inserted into neck tissue [5]. Currently, there is little experimental data relating needle force to depth. To determine the forces necessary to program into the haptic robotic device, a force sensing syringe was developed and cadaver experiments were performed. This paper presents the development of a syringe which can accurately measure needle insertion force and the proceeding experiments conducted using this device on a fresh frozen cadaver. The results of these cadaver needle insertions are characterized into force profiles for needle insertion force that are implemented into the haptic based CVC simulator.

Development of Aspiration-Assisted End-Cut Coaxial Biopsy Needles

Needle biopsy procedures, such as fine-needle aspiration and core needle biopsy, are used to extract tissue samples for diagnosis, and collection of larger samples allows for more accurate diagnosis of cancers. The combination of lower needle insertion force, less needle deflection, and reduced friction between the tissue and needle surface also leads to a more efficient biopsy procedure. In this research, a new end-cut-type coaxial needle with a modified aspiration mechanism has been developed to extract large tissue with minimal damage. The study shows that the clearance between the inner stylette and external needle and the insertion speed are the key factors affecting the biopsy performance including syringe friction force and amount of tissue extracted. Larger tissue samples (gelatin and chicken breast are used as samples here) can be obtained when inserting at lower speeds and using coaxial needles with smaller clearances between the external needles and inner stylettes. For solid samples (gelatin), the space inside the external needle is nearly filled with the solid sample. For samples consisting of both solid (chicken meat) and liquid components, a slower needle insertion results in extraction of more liquid than solid. To extract larger solid samples, high-speed needle insertion is required. This paper presents the design and manufacture of the system, protocol to evaluate the needle biopsy, and evaluation of the needle biopsy performance using gelatin and chicken breast as tissue samples.