Skin tissue biopsy device

A tissue biopsy device comprising an inner needle loaded by a first spring and held in place by a first trigger; an outer needle loaded by a second spring and held in place by a second trigger; an outer housing that surrounds the first and the second needles; and a handle attached thereto.

FIELD

The present disclosure relates to biopsy devices and, more particularly, to a skin tissue biopsy device.

BACKGROUND AND SUMMARY

This section provides background information related to the present disclosure which is not necessarily prior art. This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

Skin tissue biopsies are commonly used to extract skin from a person's body to either study for research or for clinical diagnostic purposes. The present teachings provide a skin tissue biopsy device that can extract a piece of skin with minimum pain and store it for research and disease diagnosis. Separate from the new tissue biopsy device, the present teachings further provide a tissue storage and transportation device. The two devices can be used in combination for any skin biopsy application that requires a relatively fast procedure, minimum pain, ease of performance, and minimum invasiveness. These applications include tests for any markers for diseases such as osteoporosis, skin cancers or other skin diseases. The present teachings provide a device that contains an outer housing, two latch components, inner needle, and an outer needle. The present disclosure provides a description of the design of the components and assembly thereof.

DETAILED DESCRIPTION

With particular reference to the present teachings, the design requirements can be determined according to customer needs. Generally, the skin biopsy device of the present teachings has four different potential customers. These include the patients who need skin biopsy for diagnosis of different diseases, such as osteoporosis; the physician who will perform the skin biopsy procedure to obtain or otherwise extract sample tissue; the insurance company who will pay for the skin biopsy; and the technician who will analyze the tissue sample.

Different customers have different requirements in connection with skin biopsy devices. Specifically, patients typically require minimum invasiveness and minimum pain during the skin biopsy process. The physicians require that the procedure of obtaining sample tissue be simple and fast, and the device be reliable and present low risks of complications. The insurance companies require that the device have a low cost and improve the patient outcomes at the same time. The technicians require that the sample tissue is taken from the dermal layer of the skin and the handling of the extracted sample is minimized before imaging. In many cases, it is necessary to ship the tissue sample from physician to technician; therefore it is desirable to store the sample tissue for 3-4 days.

Engineering specifications corresponding to each customer requirement can be assembled. To this end, it was determined that to minimize the pain that the patient feels, the pain of any procedure associated with the present biopsy device should be compared to a simple needle injection of gage24and should require no anesthesia and stitches. To minimize the invasiveness, it was determined that the cut diameter should be between about 0.5 to about 1 mm—because a diameter larger than 1 mm will cause much pain and less than 0.5 mm may not be sufficient to obtain a useful sample. The cut depth should be around about 3 mm, because of the depth of dermal layer at the sample location.

To make the skin biopsy easy and fast to perform, it was determined that the steps necessary to take the sample tissue would be to 4 to 7 and takes less than about 5 minutes. This time duration was chosen because the procedure requires sterilization, sampling, and storing and a duration greater than about 5 minutes may compromise sample quality. To achieve the reliability of the procedure, the device should be able to extract tissue sample from skin. To minimize the manufacture cost, the skin biopsy device should be less than 20 US dollars. To ship the sample tissue from physician to technician, the device should store the sample tissue and maintain the nano-scale structure of the tissue for more than 72 hours, which is enough for overnight mail. To help the technician for imaging, it is desirable to easily separate tissue from the device. To minimize the handling of the sample tissue, the handling by the technician should be limited to about 3-5 times before viewing, such as separating the tissue sample, cutting the tissue sample and set it for imaging. In addition, to meet the medical design regulations, all material should be able to be sterilized. The customer requirements and engineering specification developed are presented in Table 1.

TABLE 1Customer Requirements and CorrespondingEngineering SpecificationsCustomer RequirementsEngineering SpecificationsMinimum painPain compared to a simple needleinjectionMinimum invasivenessCut diameter 0.5-1 mm, depth <3 mmFast to performProcedure time <5 minEasy to perform4-7 steps for nurse practitioner levelReliability of deviceAble to obtain tissue sample from skinLow costManufacture cost <20 US dollarsStore tissue for shippingMaintain nano-scale structure for 3-4daysWeight <50 gPrepare tissue for imagingSample that can be cut to 10 micronsby 10 microns to put under AFMAble to separate the tissue from thedeviceMinimizing handling forTechnician only touches sample 3-5imagingtimes before viewing it

It was determined that the most important requirement is a procedure that is minimally painful. Minimizing the pain of the procedure will increase the adoption rate of the skin biopsy method for diagnosis of different diseases. The second important requirements are reliability, and shipping and storage of the sample tissue as they determine whether technician can analyze the skin sample and find out whether the patient has a certain disease or not. Minimum invasiveness is also important as it is related to the pain the patient feels and the time it takes for the wound to heal. The quality of tissue preparation is important, as a qualified sample is necessary for imaging. Speed and ease of use are secondary considerations, yet remain important for rapid adoption by physicians. Cost is a tertiary concern for the initial device, as subsequent engineering refinement for mass production will lower per device cost.

Concept Generation

To generate different concepts for the skin biopsy device, a functional decomposition was conducted to decide what fundamental steps the device will take. The functional decomposition diagram is inFIG. 1. Five main concepts for tissue extraction are: cutting, blade, clamp, needle, and shave. The main concepts are shown in the concept tree inFIG. 2. The cutting concept comes from the idea of scissors. The blade concept came from the idea of a knife cutting through skin. The clamp concept came from the idea of grabbing something that closes in on the object. The needle concept came from the idea of drawing blood using needle and also needle biopsies. Lastly, the shave concept came from the idea of a dish style scoop. Each design is evaluated for how they met customer requirements.

As can be seen inFIG. 3, the handles are made of plastic or any other suitable material. A hemispherical encasing space is attached to the cutting blade to protect the sample after it is cut. The cutting blades are indented to enable the device to cut off a circular piece of skin in practice. In practice, the doctor or nurse will hold the scissors by the handles and place the circular part near the desired skin area. The blades are then closed together and a small part of skin will be compressed into the cutting blade area and a small part of tissue will be cut off. Next, the encasing is opened by its hinges and OCT (Optimal Cutting Temperature medium) solution is injected to protect the cut tissue. Then the encasing is closed again and secured by the latch for transportation to a lab.

The advantages and disadvantages of the cutting design are shown in Table 2. The device does not punch into the skin, so the invasiveness is low. Although the cut tissue might contain both epidermis and dermis, the desired tissue from the dermal layer will still be acquired through the standard cryostat process. The major defection of this design is the sealing issue. Even if there is a latch to close the encasing tightly, there might still be some solution leak unless some better sealing methods are applied at the closing edges of the encasing.

TABLE 2Advantages and disadvantages of cutting designAdvantagesDisadvantagesEasy to performNot reliableFast to performNot ready for imagingLow invasivenessLeakAble to store sample

The blade concept is derived from the idea of using the blade to cut off tissue in the dermal layer. As seen inFIG. 4, there are three main components in the design: blade, housing114, and a sample receptacle assembly116with special solution in it. When the latch is pressed, the blade inserts in to the skin. The blade is constrained from turning at first. But after the blade has fully inserted into the skin, it can be turned by a spring loaded gear, which translate linear motion of the gear into rotation of the blade.

In practice, the device is first put on the desired position of the skin sample and the button at the top of the device is pressed. Next, the latched is pressed and the blade will be inserted into the skin. Then the blade will be twisted or rotated to cut an amount of tissue off. Finally, the device is pulled out and screwed into the bottle with OCT.

TABLE 3Advantages and Disadvantages of Blade DesignAdvantagesDisadvantagesFast to performRelatively high costEasy to performReliability is unknownAble to store tissue for shippingPainful

The idea of clamp comes from the mechanical pencil inner structure. As can be seen inFIG. 5, Cylinder 1 is the main body and is connected with Cylinder 3, which is composed of the dashed lines and the three small blades inFIG. 5. The position of Cylinder 3 can be adjusted to control the cut depth. A spring is attached between Cylinder 1 and Cylinder 2. When Cylinder 2 is kept up by the spring, three blades are open, and when Cylinder 2 is pushed down, the blades will be closed to punch into the skin and take the sample off.

TABLE 4Advantages and disadvantages of clamp designAdvantagesDisadvantagesLow costRequire trainingEasy to useNot reliableFast to performDifficult to separate tissueMight be painfulDifficult to manufacture

The idea of shave concept comes from a kitchen utensil, the dish style scoop. As shown inFIG. 6, the dowel cylinder inserts into and out of the hollow cylinder just like the way a syringe works. The spring connects the outer end of the dowel and the inner stopper attached to the inner wall of the cylinder. The end of the dowel is carved with gear teeth meshing with the gear, to which an arc blade is welded with the same rotation axis. As the dowel is inserted into the cylinder, the gear is driven and the arc blade is rotated by around 180°, cutting a piece of tissue off. Then the dowel is released and repulsed by the spring and the arc blade is rotated in the opposite direction by 180° back to the original position.

The advantage of this design is the whole process of cutting off the tissue is fast and easy. The invasiveness is also small because the arc edge of the end of the cylinder enables the arc blade to obtain the sample at the same horizontal level of the cylinder end. However, the whole biopsy process includes punching and rotating and the patient may feel pain. In addition, since the mechanism is complicated and the device is supposed to be as small as possible, it will be very difficult to fabricate the small parts.

TABLE 5Advantages and disadvantages of shave designAdvantagesDisadvantagesLow invasivenessPainfulFast to performDifficult to store and handle for imagingEasy to performDifficult to fabricate

This design is inspired by the biopsy needle. As shown inFIGS. 7-19, biopsy device100of the present teachings comprises an inner needle110, an outer needle112, a shell or housing114, and an optional and separate sample receptacle assembly116having a predetermined biopsy solution contained therein. In some embodiments, inner needle110can be fixed while outer needle112is spring loaded and operable to move relative to inner needle110to achieve a cutting and containing operation. Outer needle112can be triggered by a latch mechanism118disposed on housing114and operated by a user.

The general procedure of operating biopsy device100, in some embodiments, is described below. At step 1, inner needle110is inserted into the skin surface and an upper or first trigger latch120of latch mechanism118is pressed. At step 2, as deployment of inner needle110triggers outer needle112(via a second trigger latch122), outer needle112will cut into the skin and obtain the skin sample. At step 3, biopsy device100is pulled out and screwed or placed into sample receptacle assembly116with special solution.

TABLE 6Advantages and disadvantages of needleAdvantageDisadvantageMinimum painRelatively high costMinimum invasivenessReliability is unknownFast to performEasy to performAble to store tissue for shipping

Concept Comparison

With the cutting, blade, clamp, shave and needle concept given, we generated a Pugh Chart according to the customer requirements, as shown in Table 7. Minimum pain for patient, reliability of obtaining desired sample and the tissue shipping and imaging are considered the most valuable and give them the highest weights. From the Pugh Chart, the biopsy needle concept is seen as the best idea with highest rating and is further refined.

The invention and its minor variations are described below.

This design is inspired by a standard biopsy needle, but contains several improvement not found in the prior art. As shown inFIG. 8, there are four main components in the design: inner needle110, outer needle112, housing114, and an optional and separate sample receptacle assembly116with special solution in it. Both inner needle110and outer needle112are spring loaded. Inner needle110can be triggered by upper trigger latch120of latch mechanism118and outer needle112can be triggered by lower trigger latch122of latch mechanism118when inner needle110contacts lower trigger latch122of latch mechanism118. In some embodiments, upper trigger latch120can comprise an elongated flexural member or living hinge to permit articulation and elastic movement thereof. In other words, the elongated flexural member or living hinge of upper trigger latch120can comprise a localized flexure joint along a beam member. In some embodiments, upper trigger latch120can be formed as a monolithic or unitary member associated with surrounding structure, such as the inner cylinder160(FIG. 11). Specifically, in some embodiments, upper trigger latch120can comprise a monolithically/unitary formed elongated beam having a distal latch end162for engaging associate latching structure formed on adjacent housing or inner cylinder164bthat is capable of elastic deformation. The elongated beam can comprise a protruding button124for actuation by a user.

TABLE 7Pugh Chart for different concept designsCustomer RequirementsWeightsCuttingBladeClampShavingNeedleTotalMinimum pain9333345Minimum invasiveness7434445Fast to perform3434345Easy to perform4233345Reliability of obtaining8443445sampleAble to be sterilized4442245Low cost2444245Store tissue for shipping8243245Prepare tissue for imaging7243245Minimizing handling for6233235imaging5859.67062.65678100

The procedure of operating biopsy device100is described below. At step 1, biopsy device100is placed in direct contact on the patient's skin in a position where the biopsy is to be taken and upper trigger latch120is actuated via a button124by the healthcare provider. At step 2, as the button124triggers inner needle110, inner needle110is propelled into the skin in response to spring force. The spring force is a product of compression of first extension spring130compressed between an inner flange132of housing114and an outer flange134of inner needle110. During this process, inner needle110will contact lower trigger latch122of latch mechanism118and consequently and automatically trigger outer needle112—this can be timed such that it occurs once inner needle110has deployed a predetermined distance into the patient's tissue (e.g. fully deployed, partially deployed). Specifically, a notch136formed in the shank of inner needle110contacts a top surface138of outer needle112thereby overcoming lower trigger latch122. It should be appreciated that a biasing force of lower trigger latch122must be less than the force caused by contact of the deploying inner needle110to outer needle112. Lower trigger latch122can comprise a biased member140slidably received within a retention notch142formed in outer needle112. In some embodiments, retention notch142can comprise a sloped surface144to encourage disengagement of lower trigger latch122from outer needle112upon contact of notch136of inner needle110with top surface138of outer needle112. Thereafter, outer needle112will be disengaged from lower trigger latch122and outer needle112is propelled into the skin in response to spring force. Outer needle112includes a sharpened distal tip operable for cutting tissue surrounding inner needle110and retaining a portion thereof between outer needle112and inner needle110. The spring force is a product of compression of a second extension spring146compressed between an inner flange148of housing114and an outer flange150of outer needle112. At step 3, biopsy device100is pulled out of the skin and screwed into sample receptacle assembly116with special solution.

A SolidWorks model was created relating to the present invention.FIG. 9illustrates how the CAD model is related to the drawing. The specific CAD drawing of the latches are shown in the later sections.

Three specific states of biopsy device100are shown inFIG. 10. State1is the start state at which first extension spring130and second extension spring146are compressed. When a user actuates latch mechanism118via button124, the first extension spring130will be released and accelerate inner needle110downward and will be pushed into skin as shown in State2. When inner needle110or associated structure contacts a physical stop, such as outer flange134of inner needle110and inner flange148of housing114, lower trigger latch122is released as described herein. Outer needle112will be pushed into skin as shown in State3. At this stage, the skin sample will stay between inner and outer needles110and112respectively.

After refining the present design, detailed CAD drawings of the assembly were developed as illustrated inFIGS. 11-14shows the detailed assembly of the biopsy part andFIGS. 15-17illustrate the interface of biopsy device100and sample receptacle assembly116.

With particular reference toFIGS. 11-14, in some embodiments, biopsy device100can comprise a multi-piece housing and cylinder assembly to provide a robust and reliable construction and operation. Specifically, biopsy device100can comprise inner needle110being coupled to an inner cylinder160for movement therewith. Inner cylinder160can comprise upper trigger latch120, including button124and a latch end162. Inner cylinder160can be generally tubular in shape.

Inner cylinder160can be slidably disposed within an inner housing164having opposing housing halves164aand164b. Halves164aand164beach include an inner volume that is sized and shaped to slidably receive inner cylinder160, as illustrated inFIGS. 12 and 13, and the halves can be joined together via fasteners. In this embodiment, first extension spring130can be disposed between a top surface of inner cylinder160and an inner top wall of inner housing164, thereby exerting a biasing force therebetween. Similarly, second extension spring146can be disposed between inner flange148′ of inner housing164and outer flange150of outer needle112, thereby exerting a biasing force therebetween.

Inner needle110passes through the second extension spring146and the hollow outer needle112.

Outer housing114can comprise halves114aand114b. Halves114aand114beach include an inner volume that is sized and shaped to slidably receive inner housing164, as illustrated inFIG. 14, and the halves can be joined together via fasteners. Outer housing114is sized to be grasped by a healthcare provider during deployment of inner needle110and outer needle112.

When the button on the upper trigger latch120is pressed, the upper trigger latch120will bend and hence release inner needle110. Inner needle110will then insert into the skin. As inner needle110goes down, the cylinder connected to inner needle110will touch the bumps of the lower trigger latch122and push the lower trigger latch122away, the lower part of the lower trigger latch122will then release outer needle112and outer needle112will cut through the skin and obtain a skin sample between the inner and outer needle. After obtaining the skin sample, the whole device will be pulled out. Then by pulling the handle or release member166connected to outer needle112up and rotating handle166into a retaining slot167formed in housing164, outer needle112will be pulled up and expose the skin sample held by inner needle110. Biopsy device100can then be interfaced with the storage device to store the tissue for shipping or handling.

Sample receptacle assembly116is composed of two parts: The plastic base180and the plastic mold182. The plastic base180has inward bumps184that fit the shape of the outer housing114of biopsy device100and fixes or retains biopsy device100tightly. The plastic mold182has a basin186for injecting OCT, and a small groove188is left on the edge of the thin wall to hold inner needle110. When inner needle110is put on the mold with OCT solution, the notch190(FIG. 8) formed in inner needle110holding the tissue is faced downwards to let the tissue be exposed to OCT. Then, according to a standard tissue storage process, the whole device is put into an aluminum box filled with dry ice and is frozen for storage and shipping. When biopsy device100is taken out, the extraction device is removed, with the tissue left in the OCT plate.

For purposes of exemplary construction, the following dimensions are provided. However, it should be understood that variations in both size and shape are anticipated by the present disclosure.

Upper Trigger Latch120

The dimension of the upper trigger latch120is shown inFIG. 18. The width of the latch is 4 mm, the thickness of the latch is 1.5 mm, and the length of the latch is 25 mm. The button is in the middle of the latch. If the button is pressed, the flexural structure of the latch will bend inside. The lower part of the latch will no longer be held by the inner housing and therefore it will release the whole cylinder connected with latch and also inner needle110connected to the cylinder. We make the thickness of the latch as small as 1.5 mm so that the maximum stress the upper trigger latch120will experience is smaller than the plastic's yield stress and the latch is still safe from buckling.

Lower Trigger Latch122

The dimension of the lower trigger latch122is shown inFIG. 10. The thickness of the latch is 1.6 mm and the length of the latch is 32 mm. The two bumps are located 18 mm from the upper end of the latch. When inner needle110goes down, the cylinder connected to the needle will push the bumps of the lower trigger latch122. The lower trigger latch122will then be bent to the outside. When inner needle110stops, the lower trigger latch122will then be completely pushed aside and release outer needle112. To make the maximum stress the lower trigger latch122experience smaller than the yield stress of plastic and make the lower trigger latch122safe from yield caused by tensile force, the thickness of the latch is chosen to be 1.6 mm.

The dimension of inner needle110is shown inFIG. 20. The diameter of inner needle110is 0.7176 mm, the total length of inner needle110is 26.796 mm, and the groove on the needle is 0.4784 mm deep and 1.576 mm long. After inner needle110inserts into the skin surface, the skin will expand into the groove and surround the needle.

Inner needle can comprise a generally elongated cylindrical shape having a head portion and a shank portion, wherein the shank portion includes a recessed pocket portion or groove formed in the shank portion. The recessed pocket portion is sized to retain the tissue biopsy sample therein. It should be appreciated that alternative cross-sectional shapes, such as square, can be used.

The dimension of outer needle112is shown inFIG. 21. The inner diameter is 0.7176 mm and the outer diameter is 0.9576 mm, the total length of outer needle112is 9 mm. The cylindrical plate or outer flange150on top of outer needle112has a diameter of 7 mm and thickness of 2 mm. After inner needle110inserts into the skin, outer needle112will cut through the skin. Therefore, a small piece of skin sample will be left between inner needle110and outer needle112.

Material List

With all the components determined, a list of all the parts is shown in Table 8. This list includes the part number, part name, quantity, material, size, mass, manufacture process, function and cost. It should be understood, however, that the present material list represents merely one embodiment of the present teachings and variations and modification are anticipated (e.g. size, shape, material type, color, finish, and the like). The material list merely represents an exemplary configuration.

According to the principles of the present teachings, there are several unique functional features of the proposed skin tissue biopsy device:i) Extracts tissues from a relatively small depth (<5 mm, typically 2 mm), most other biopsy devices extract tissues from much deeper;ii) Does the above in a minimally invasive manner (existing skin biopsy devices cause considerable pain and leave a large exposed cut, left to heal over time);iii) Biopsy device100offers a single step operation. The healthcare provider (nurse or doctor) presses a single button to carry out the entire process. There are no careful adjustments to make or complicated procedure to follow; andiv) Purely mechanical construction, minimal part counts, and low-cost.