Surgical needles are commonly used by medical professionals to reach target locations inside of the body for disease diagnosis or other medical interventions — such as biopsy, brachytheraphy, thermal ablation, and drug delivery [1, 2]. The effectiveness of these procedures depends on the accuracy with which the needle tips reach the targets, such as tumors or certain organs/tissues. In procedures, such as deep brain stimulation and prostate brachytheraphy, it is impossible to reach the surgical sites via simple needle trajectory because of anatomical constraints. Although needles are considered minimally invasive devices, needle insertion still causes tissue damage of varying degrees so it is desirable to reach multiple targets, or multiple sites on a single target, to obtain multiple high-quality biopsy samples with each insertion [1, 2]. Recently there has been a substantial and growing interest in the medical community to develop innovative surgical needles for percutaneous interventional procedures. The answer to the challenge of developing advanced surgical needles could be found in nature. Insects such as honeybees (Fig. 1), mosquitos, and horse flies have sophisticated sting mechanics and stinger structures, which they use to steer their stingers to a specific target, such as a human, and to release their venom in a certain path in skin [3]. We are studying these mechanisms, evolved in nature over millions of years, as a basis to develop bioinspired needles. Surgical needles are typically consisted of a hollow cylindrical component (cannula) and an inner solid cylindrical component (stylet). Our hypothesis is that a surgical needle (stylet) that mimics insect stinger mechanics and structures can be easily controlled for sophisticated needle steering during surgery and can result in more effective and less invasive percutaneous procedures. The focus of this work is to mimic honeybee stinger such as shown in Fig. 1 to design innovative surgery needles. One of the critical issues in designing surgery needles is the insertion force required to penetrate and to navigate the needle inside the tissue [2]. Larger insertion forces increase tissue damages thus may result in a more painful procedure [2]. Another consideration is the needle trajectory path (needle tip deflection) and the difficulty to control the needle path. The needle deviates from the target and thus it is very difficult to navigate the needle in the tissue. There is a need to design advanced surgery needles that provide smaller insertion force. This can lead to a less invasive procedure, in other words, less tissue damage and pain [3]. The needle trajectory path of these new needle designs must be understood for the needle design optimization. As stated previously, it is hypothesized that a honeybee-inspired needle can be utilized to reduce the insertion force. In this work, the experimental work to understand the mechanics of bioinspired needles is presented. 3D printing of the needles and their insertion tests are performed to investigate the effect of the needle designs on the insertion force and the needle deflection (trajectory path) curves. Understanding these factors should shed some lights on some design parameters to develop innovative surgery needles.

Shape memory alloy (SMA) based active needles [1] have shown the potential to introduce remarkable improvements to many percutaneous needle-based procedures such as thermal ablation, brachytherapy and breast biopsy. Brachytherapy for instance is a common procedure to treat early stage prostate cancer because its superior clinical outcome. Prostate cancer is sex specific and only affects males; it is more prevalent in elderly males, ages 65–74 years old [2]. There is projected to be a 24% increase in cancer cases for men by 2020, this would mean approximately 1 million new cases each year [3]. There was a study in 2015 [4] that examined the needle placement accuracy for brachytherapy procedure while implementing the use of a 3D navigation system, Surgical Planning and Orientation Computer System. The study examined the Target Registration Error (TRE) for single and multiple needle placements. Analysis of the 250 different targets showed a mean Target Registration Error for single needle applications of (1.1 ± 0.4 mm), (0.9 ± 0.3 mm), and (0.7 ± 0.3 mm) in the x, y, and z directions, respectively. The maximum deviation was found 2.3 mm. In another study by Podder et al. [5], the effects of dose distribution has been discussed which has a high influence on the clinical outcome. The study shows that the curvilinear approach by the active needle would introduce the potential for improving dose distribution, reducing number of needles and resulting is better clinical outcome. Actuating the surgical needles for higher accuracy, SMAs are considered as suitable actuators [6] because of their lightweight, high force and energy density. However, SMA actuated needle will be more complex and may incur additional inaccuracy; thereby after development of a robust active needle, control studies sound very necessary. The focus of this work is to introduce an innovative design of an active needle, and to fabricate the device to demonstrate its capability of creating a high maneuverability at the needle tip. This design of the active needle privileges from actuation of a comparatively long SMA wire to create a considerable amount of deflection, while minimizing the tissue rupture. Most of the needles today are made of stainless steel, titanium or Nitinol; they are ensured to be sturdy enough to puncture the tissue and overcome its resistance during insertion. This would limit the flexibility of the needles. In our previous designs [7,8], a joint element was included in design to provide more dexterity to the needle’s structure. Despite of the fact that this soft element increased the needle’s flexibility; the design introduced a high tissue rupture during actuation because of the gap between the body of the needle and the SMA actuator. The amount of rupture was increasing with larger deflection of the needle. This work decreases the rupture to a reasonable amount while even a higher deflection compared to our previous design is achieved. Table 1 lists general specifications and approximations of dimensions and requirements that have been tried to be addressed in the current design as much as possible. There will be still future work to meet some other factors discussed at the end of this study.

Cardiovascular diseases including atherosclerosis, thrombosis, aneurysm and arrhythmia remain the major cause of mortality in developed countries, accounting for 34% of deaths each year [1]. Commonly used minimally invasive vascular intervention with using catheters leads to higher success rate than open surgery [2]. Integrating robotic technologies into active control of catheters in teleoperation manner has promised to reduce radiation exposure to surgeons and improve accuracy during electro-physiological (EP) procedures [1]. Common used commercial robotic EP catheter platforms such as Sensei (Hansen Medical Inc., USA) and Niobe (Stereotaxis Inc., USA) are usually composed of a catheter driver (slave side) which can be remotely controlled by a console operator (master side). However, the Sensei catheters are more rigid and bigger than standard catheters because of their two-layer-sheath structure; and Magnetic Niobe systems are huge and expensive. In this paper, we propose a mechanism of remote-driving catheterization platforms in which a commercial tip-steerable ablation catheter (St. Jude Medical Inc., USA) (Fig. 1) is manipulated by a catheter driver in three degree of freedoms (DOF) (insertion/withdrawal, rotation and tip deflection). In addition, we also present the design of the control software based on Object-Oriented Programming (OOP) method which is expected to give the other researchers a guide line during robotic catheter design.

A Stellite 25 17mm tube valve based upon the Björk-Shiley Monostrut (BSM) valve design was developed for use in the Penn State Pediatric Ventricular Assist Device (PVAD) pump [1]. The hook of the valve was designed to hold a Delrin occluding disc in place while allowing the disc to tilt open 70 degrees from the closed position. Unlike common design constraints which remain in the elastic region, the hook experiences plastic deformation twice during the assembly process, making the material choice of Stellite 25 imperative. Stellite 25 is a cobalt-chromium-tungsten-nickel alloy (Co-20Cr-15W-10Ni) belonging to the material family of superalloys which are commonly used for wear-resistant applications exposed to heat, abrasion, and galling [2, 3]. Along with its excellent in vivo corrosion resistance [4], Stellite 25 exhibits high strength and ductility which permit the hook to be plastically deformed during disc installation while remaining below the strain to failure [3, 4]. Together these qualities make Stellite 25 an ideal material choice for the 17mm tube valve application. Predicting the resultant stresses and strains is critical for determining the safety and structural reliability of the Stellite 25 17mm tube valve for the PVAD after assembly. After performing finite element analysis (FEA), the simulation results were validated by deflection experiments and metallurgical investigations.

An estimated 623,000 individuals are living with a major lower leg amputation in the United States [1]. Of these amputations, 78% were due to peripheral vascular disease (PVD) and 45% were due to PVD in individuals with type I or II diabetes [2]. With diabetes and PVD incidence levels on the rise [1] and those in a depressed socio-economic situation more susceptible to develop type II diabetes [3], the demand for affordable, high quality ankle prostheses has never been higher. Prostheses currently available on the market include both passive and active devices, neither of which fully satisfies user requirements. Passive prostheses, the more commonly prescribed style, are economically priced but lack the powered push-off observed in a natural ankle [4] due to the absence of an actuator. As a result, passive prostheses cause a multitude of quality of life detriments to the end user including asymmetrical gait (for unilateral amputees), slower self-selected walking speeds, higher metabolic cost per distance traveled and increased pain in the residual limb [5–6]. Conversely, active devices can nearly match the functionality and powered push-off of a natural ankle [7] but are cost prohibitive. Among active devices, one of the most successful models is the BiOM. Initially developed at MIT, the BiOM uses an actuator in series with a spring to achieve near natural ankle behavior. In 2013, two years after the product’s official launch, the device cost approximately $50,000 and had only sold about 1,000 units [7]. The limitations of currently available ankle prostheses motivates work on a new solution, the EaSY-Walk (Early Stance Y-deflection), a passive ankle device that mimics several key aspects of a natural ankle joint, especially nonlinear rotational stiffness and rotational work output (powered push-off) that increases with walking velocity while remaining relatively inexpensive.

Needle insertion is a common surgical technique used in diagnosis (e.g. biopsy) and prognosis (e.g. brachytherapy) of several diseases. The success of such procedures highly depends on the accuracy of needle placement to target locations. Accuracy of the needle placement is presently limited due to movement of tissue, inability to control needle deflection, and inaccessibility of image monitoring techniques. These limitations are being addressed by using active (or smart) needles (e.g. see Fig. 1) that can maneuver within the tissue with the aid of actuators attached to the needle body [1–3]. However, in these studies, active needles were studied in air but not inside the tissue where they are supposed to be used. Therefore, to develop active needles that are feasible for clinical applications, it is necessary to understand the mechanics of active needles within the tissue.

Understanding the kinematics of the lumbosacral spine and the individual functional spinal units (FSU) is essential in assessing spine mechanics and implant performance. The lumbosacral spine and the FSU are comprised of bones and complex soft tissues such as intervertebral discs (IVD) and ligaments. Prior studies have focused on the behavior of isolated structures, but the contribution of each structure to the overall kinematics of the spine needs to be further understood. In this study, the behavior of various structural conditions was determined by experimentally dissecting each ligament in a stepwise fasion until only the IVD remained, and applying loading conditions to the FSU. The FE model was validated through optimization to match the in vitro load-deflection characteristics and contact mechanics for the various structural configurations.

In this article we present a finite element simulation of an active steerable surgical needle. The highly maneuverable actuated needle can be utilized in many cases involving diagnostic and therapeutic percutaneous procedures; for example, in prostate brachytherapy. To make the surgical needle able to navigate through the tissue accurately, avoiding sensitive organs, external bending forces are being provided by smart actuators attached to the needle body (see Fig. 1). The shape memory alloy (SMA) wires, namely Nitinol, with unique properties of super-elasticity, shape memory effect, and biocompatibility are suitable as an actuator. The attached SMA wires contract when heated due to the phase transformation and therefore bends the needle. A 3D finite element (FE) model of the SMA actuated steerable needle was developed and validated by a prototype to show the feasibility of the design and also to study the factors influencing needle deflection.

Compliant mechanisms are flexible devices that transform an input force to a displacement through elastic deformation. Advantages of using compliant mechanisms are that they are monolithic devices that contain flexible members that can undergo large deflection, have fewer joints, have increased reliability, increased precision and have fewer components compared to rigid-body mechanisms.

This research highlights the design, fabrication and experimental validation of a Shape Memory Alloy (SMA) actuated robotic catheter. The prototype consists of four SMA tendons that actuate a central tubular substructure in two orthogonal directions. The experimental shape memory characteristics are used to optimize the design. Joule heating is used to generate tip deflections and the experimental bending characteristics are obtained using a dual camera imaging system. These measurements reveal important nonlinearities and hysteretic characteristics of the system. A dynamic model of the system is developed to describe the SMA-effected bending mechanics, and simulation results are compared to experimental measurements for model validation. The applicability of this technology to cardiovascular procedures, like atrial ablation, is demonstrated through precise tracking of trajectories using PID control.

A finite element model of the left atrium, incorporating detailed anatomical features and realistic material characteristics, was built to investigate the interaction of heart tissue and surgical instruments. This model was used to facilitate the design of an endoscopically deployable atrial retractor for use in minimally invasive, robotically assisted (MIRA) mitral valve repair. The left atrial geometry was imported directly from MRI data of an explanted porcine heart, and material properties were derived from experimental testing of cardiac tissues. Model accuracy was verified by comparing simulated cardiac wall deflections to those measured by MRI. Finite element analysis was shown to be an effective tool for analyzing instrument/tissue interactions and for designing surgical instruments.