Strain gauge stabilization in a surgical device

An adapter assembly is provided and includes a tubular housing having a proximal end portion and a distal end portion and defining a longitudinal axis; a load sensing assembly disposed within the tubular housing in contact between a proximal surface and a distal surface, the proximal and distal surfaces perpendicular to the longitudinal axis, the load sensing assembly configured to measure a load exerted on the tubular housing, the load sensing assembly including a sensor body; and a gimbal disposed between a sensor body surface and at least one of the proximal surface or the distal surface, the gimbal configured to isolate the sensor body from the load exerted in a plane perpendicular to the longitudinal axis.

BACKGROUND

1. Technical Field

The present disclosure relates to surgical devices. More specifically, the present disclosure relates to handheld electromechanical surgical systems for performing surgical procedures having reusable components with load sensing devices.

2. Background of Related Art

One type of surgical device is a circular clamping, cutting and stapling device. Such a device may be employed in a surgical procedure to reattach rectum portions that were previously transected, or similar procedures. Conventional circular clamping, cutting, and stapling devices include a pistol or linear grip-styled structure having an elongated shaft extending therefrom and a staple cartridge supported on the distal end of the elongated shaft. In this instance, a physician may insert the loading unit portion of the circular stapling device into a rectum of a patient and maneuver the device up the colonic tract of the patient toward the transected rectum portions. The loading unit includes a cartridge assembly having a plurality of staples. Along the proximal portion of the transected colon, an anvil assembly can be purse-stringed therein. Alternatively, if desired, the anvil portion can be inserted into the colon through an incision proximal to the transected colon. The anvil and cartridge assemblies are approximated toward one another and staples are ejected from the cartridge assembly toward the anvil assembly thereby forming the staples in tissue to affect an end-to-end anastomosis, and an annular knife is fired to core a portion of the clamped tissue portions. After the end-to-end anastomosis affected, the circular stapling device is removed from the surgical site.

A number of surgical device manufacturers have also developed proprietary powered drive systems for operating and/or manipulating the end effectors. The powered drive systems may include a powered handle assembly, which may be reusable, and a disposable end effector that is removably connected to the powered handle assembly.

Many of the existing end effectors for use with existing powered surgical devices and/or handle assemblies are driven by a linear driving force. For example, end effectors for performing endo-gastrointestinal anastomosis procedures, end-to-end anastomosis procedures and transverse anastomosis procedures, are actuated by a linear driving force. As such, these end effectors are not compatible with surgical devices and/or handle assemblies that use rotary motion.

In order to make the linear driven end effectors compatible with powered surgical devices that use a rotary motion to deliver power, a need exists for adapters to interconnect the linear driven end effectors with the powered rotary driven surgical devices. These adapters may also be reusable, and as such, need to able to withstand multiple sterilization cycles. As these adapters are becoming more sophisticated and include various electronic components, there is a need for electronic components disposed within the adapters that can withstand multiple autoclave cycles.

SUMMARY

Powered surgical devices may include various sensors for providing feedback during their operation. However, one limitation of the electronics and sensors used in the sterile environment of the operating room is that they need to be designed to withstand multiple cleaning and autoclave cycles. In order to gather information on the mechanical forces applied by the powered surgical devices, load sensing devices, such as load cells, are disposed on one or more mechanical components of the powered surgical device and/or adapters coupled thereto.

Powered surgical devices utilizing strain gages enable the user to have force awareness feedback which can enable a number of advantages. Benefits of force monitoring include anvil detection, staple detection, cutting, controlled tissue compression to avoid tissue damage while maximizing staple formation consistency, excessive load adjustment of stroke to optimized staple formation, tissue thickness identification, and the like. Due to the sensitivity of the load sensing devices, any unintended forces or strains on the gage can negatively impact the accuracy of the device.

The present disclosure provides for an adapter assembly having a loading sensing device and a gimbal disposed in the constraint condition of the load sensing device. The load sensing device is disposed between two parallel opposing surfaces and measures the strain imparted thereto due to actuation of various actuation assemblies within the adapter assembly. The position of the load sensing device between two opposing parallel surfaces introduces off-axis variations in the orientation of a trocar assembly, which changes the load on the load sensing device and consequently the accuracy of the measurements. Placement of the gimbal allows the load sensing device to be loaded only in a uni-axial strain, namely, in a longitudinal direction, without additional moments or off-axis loads, namely, in a plane perpendicular to the longitudinal axis. The gimbal is a dual-rocking mechanism that allows rotation at the point of loading on the load sensing device so that changes in orientation of the trocar assembly do not affect the loading condition of the load sensing device.

Load sensing devices are also coupled to signal processing and conditioning circuit that are separately packaged from the load sensing devices. These circuits process the change in resistance of the load sensing devices and determine the load applied thereto. In particular, components of signal processing circuits are usually disposed on printed circuit boards (“PCB”) housed with other electronic and electric components of powered surgical devices. Remote placements of these circuit components away from the load sensing devices is due to their size and shape, which prevent the PCB from being in close proximity to the load sensing devices. Accordingly, these circuits are connected to the load sensing devices through wired connections, which involve longer leads (e.g., flexible printed circuit traces over 10 centimeters) for transmitting analog signals from the load sensing devices to the signal processing circuit. Longer wired connections can result in signal loss and also increase the chances of failure due to exposure of these leads to disinfecting and sterilization cycles. Harsh environments from disinfecting solutions and residual moisture from the autoclaving processes breaks down the components and coatings in flex circuits, thereby causing signal degradation. Further, in surgical devices where saline irrigation is utilized, the saline can further breakdown of mechanical integrity of these circuits resulting in signal degradation.

In addition, the separation between the load sensing devices and the signal processing circuitry also affects fidelity of analog sense signals transmitted from the load sensing devices. The analog voltage signals are low voltage signals and are therefore more susceptible to interference of the load measured by the load sensing devices due to water ingress in the PCB, solder connections, and/or traces, small contamination including solder flux and autoclave mineral deposits, as well as radio frequency interference due to long conductor travel length. Remote placement of signal processing circuits also results in lower bit resolution. Furthermore, conventional signal processing circuits used with load sensing devices have no ability to compensate for zero balance fluctuations in load sensing devices due to inconsistencies of sensor bodies housing the load sensing devices (e.g., during manufacture and assembly of the sensors). As used herein, the term “zero balance” denotes a baseline signal from a load sensing device corresponding to a condition in which the load sensing device is unloaded.

The present disclosure provides for a combined load sensing assembly having one or more load sensing devices and a signal processing circuit disposed within a hermetically sealed housing of the sensor. This obviates the problem of transmitting analog load sensing signals along long leads and protects the load sensing devices and the signal processing circuit from exposure to elements including sterilization cycles (e.g., autoclaving). In addition, the signal processing circuit is programmable to optimize the sensor signals by adjusting gain and offset values of sensor signals.

Conventional load sensing devices that utilize strain gauge technology typically suffer from the lack of adjustability or tuning of the load sensing devices. In particular, variations in the load sensing devices, tolerances in sensor bodies, placement of the load sensing devices, and other factors, contribute to zero balance variations, which result in variable zero balance values across the lot of load sensing devices. Unfortunately, in conventional load sensing devices zero balance cannot be adjusted for each individual load sensing device. The present disclosure provides a signal processing circuit that may be programmed to adjust zero balance after the load sensor is manufactures and/or assembled.

The present disclosure provides multiple embodiments, each of which includes multiple aspects. Various aspects of the embodiments are interchangeable among the disclosed embodiments. According to one embodiment of the present disclosure, an adapter assembly includes: a tubular housing having a proximal end portion and a distal end portion and defining a longitudinal axis. The adapter assembly also includes a load sensing assembly disposed within the tubular housing in contact between a proximal surface and a distal surface, the proximal and distal surfaces perpendicular to the longitudinal axis, the load sensing assembly configured to measure a load exerted on the tubular housing, the load sensing assembly including a sensor body. The adapter assembly includes a gimbal disposed between a sensor body surface and at least one of the proximal surface or the distal surface, the gimbal configured to isolate the sensor body from the load exerted in a plane perpendicular to the longitudinal axis.

According to another embodiment of the present disclosure, a surgical device includes: a handle assembly including a controller; an adapter assembly having: a tubular housing having a proximal end portion and a distal end portion and defining a longitudinal axis; a load sensing assembly disposed within the tubular housing in contact between a proximal surface and a distal surface, the proximal and distal surfaces perpendicular to the longitudinal axis, the load sensing assembly configured to measure a load exerted on the tubular housing. The load sensing assembly includes a sensor body; and a gimbal disposed between a sensor body surface and at least one of the proximal surface or the distal surface, the gimbal configured to isolate the sensor body from the load exerted in a plane perpendicular to the longitudinal axis; and a surgical end effector configured to couple to the distal end portion of the adapter assembly.

According to one aspect of any of the above embodiments, the load sensing assembly further includes: a load sensor circuit disposed within the sensor body. The adapter assembly may also include a signal processing circuit disposed within the sensor body and electrically coupled to the load sensor circuit.

According to another aspect of any of the above embodiments, the gimbal has a tubular shape having a width, a thickness, and a radius. The proximal surface of the gimbal and the distal surface of the gimbal includes a pair of peaks. Each of the proximal surface of the gimbal and the distal surface defines a waveform having a wavelength defined by πr, where r is the radius of the tubular shape having an amplitude that is equal to the thickness of the tubular shape. The gimbal also includes a proximal surface and a distal surface, each of the proximal surface of the gimbal and the distal surface of the gimbal has an undulating shape. The sensor body includes a tubular portion and the gimbal is disposed over the tubular portion.

According to one embodiment of the present disclosure, an adapter assembly includes a tubular housing having a proximal end portion and a distal end portion and defining a longitudinal axis. The adapter assembly also includes a load sensing assembly disposed within the tubular housing in contact between a proximal surface and a distal surface. Each of the proximal surface and the distal surface is perpendicular to the longitudinal axis. The load sensing assembly is configured to measure a load exerted on the tubular housing. The load sensing assembly also includes a sensor body, wherein at least one of the proximal surface or the distal surface includes a first surface feature and the sensor body includes a second surface feature engaging the first surface feature.

According to one aspect of the above embodiment, the first surface feature is a convex surface feature and the second surface feature is a concave surface feature. The first surface feature may be a ridge having a first curved cross-section. The second surface feature may be a groove having a second curved cross-section. The first curved cross-section and the second curved cross-section have the same radius. The sensory body is configured to pivot about a pivot axis that is transverse to a longitudinal axis defined by the sensory body. The pivot axis is defined by the ridge and passes through each of center of the first curved cross-section and the second curved cross-section.

According to another aspect of the above embodiment, the first surface feature is a concave surface feature and the second surface feature is a convex surface feature. The first surface feature is a groove having a first curved cross-section. The second surface feature is a ridge having a second curved cross-section. The first curved cross-section and the second curved cross-section have the same radius. The sensory body is configured to pivot about a pivot axis that is transverse to a longitudinal axis defined by the sensory body. The pivot axis is defined by the ridge and passes through each of center of the first curved cross-section and the second curved cross-section.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure are now described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. The embodiments may be combined in any manner consistent with the functionality of the apparatus and/or method disclosed herein. As used herein, the term “clinician” refers to a doctor, a nurse or any other care provider and may include support personnel. Throughout this description, the term “proximal” will refer to the portion of the device or component thereof that is closer to the clinician and the term “distal” will refer to the portion of the device or component thereof that is farther from the clinician. The term “substantially equal to” denotes that two values are ±5% of each other. Additionally, in the drawings and in the description that follows, terms such as front, rear, upper, lower, top, bottom, and similar directional terms are used simply for convenience of description and are not intended to limit the disclosure. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail.

The present disclosure relates to powered surgical devices having electronic sensors for monitoring mechanical strain and forces imparted on components of the powered surgical devices. More particularly, this disclosure relates to load measuring sensors including load sensing devices as well as analog and digital circuitry that are hermetically sealed such that the load sensors are configured to resist harsh environments. In the event that electrical connections of the powered surgical devices are compromised during use, measurement signals output by the sensors of the present disclosure remain unaltered. In addition, the sensors are programmable allowing for adjustments to gain and offset values in order to optimize the measurement signals.

With reference toFIG. 1, a powered surgical device10includes a handle assembly20, which is configured for selective connection with an adapter assembly30, which in turn, is configured for selective connection with an end effector, such as an annular reload40. Although generally referred to as being a powered surgical device, it is contemplated that the surgical device10may be a manually actuated and may include various configurations.

The handle assembly20includes a handle housing22having a lower housing portion24, an intermediate housing portion26extending from and/or supported on a portion of the lower housing portion24, and an upper housing portion28extending from and/or supported on a portion of the intermediate housing portion26. As shown inFIG. 2, a distal portion of the upper housing portion28defines a nose or connecting portion28athat is configured to accept a proximal end portion30bof the adapter assembly30.

With reference toFIG. 3, the handle assembly20includes one or more motors36which are coupled to a battery37. The handle assembly20also includes a main controller38for operating the motors36and other electronic components of the handle assembly20, the adapter assembly30, and the reload40. The motors36are coupled to corresponding drive shafts39(FIG. 2), which are configured to engage sockets33on the proximal end portion30b, such that rotation of the drive shafts39is imparted on the sockets33. The actuation assembly52(FIG. 6B) is coupled to a respective socket33. The actuation assembly52is configured to transfer rotational motion of the sockets33into linear motion and to actuate the reload40(FIG. 1) along with the anvil assembly58.

With reference toFIG. 4, the adapter assembly30includes a tubular housing30athat extends between a proximal end portion30bthat is configured for operable connection to the connecting portion28aof the handle assembly20and an opposite, distal end portion30cthat is configured for operable connection to the reload40. In this manner, the adapter assembly30is configured to convert a rotational motion provided by the handle assembly20into axial translation useful for advancing/retracting a trocar member50slidably disposed within the distal end portion30cof the adapter assembly30(FIG. 5) for firing staples of the reload40.

With reference toFIG. 2, the connecting portion28aincludes an electrical receptacle29having a plurality of electrical contacts31, which are in electrical communication with electronic (e.g., main controller38) and electrical components (e.g., battery37) of the handle assembly20. The adapter assembly30includes a counterpart electrical connector32that is configured to engage the electrical receptacle29. The electrical connector32also includes a plurality of electrical contacts34that engage and electrically connect to their counterpart electrical contacts31.

With reference toFIG. 4, the trocar member50is slidably disposed within the tubular housing30aof the adapter assembly30and extends past the distal end portion30cthereof. In this manner, the trocar member50is configured for axial translation, which in turn, causes a corresponding axial translation of an anvil assembly58(FIG. 1) of the reload40to fire the staples (not shown) disposed therein. The trocar member50includes a proximal end which is coupled to the tubular housing30aof the adapter assembly30. A distal end portion of the trocar member50is configured to selectively engage the anvil assembly58of the reload40(FIG. 4). In this manner, when the anvil assembly58is connected to the trocar member50, as will be described in detail hereinbelow, axial translation of the trocar member50in the first direction results in an opening of the anvil assembly58relative to the reload40, and axial translation of the trocar member50in a second, opposite direction, results in a closing of the anvil assembly58relative to the reload40.

As illustrated inFIGS. 1 and 5, the reload40is configured for operable connection to adapter assembly30and is configured to fire and form an annular array of surgical staples, and to sever a ring of tissue. The reload40includes a housing42having a proximal end portion42aand a distal end portion42band a staple cartridge44fixedly secured to the distal end portion42bof the housing42. The proximal end portion42aof the housing42is configured for selective connection to the distal end portion30cof the adapter assembly30and includes a means for ensuring the reload40is radially aligned or clocked relative to the adapter assembly30.

With reference toFIG. 5, the housing42of the reload40includes an outer cylindrical portion42cand an inner cylindrical portion42d. The outer cylindrical portion42cand the inner cylindrical portion42dof the reload40are coaxial and define a recess46. The recess46of the reload40includes a plurality of longitudinally extending ridges or splines48projecting from an inner surface thereof which is configured to radially align the anvil assembly58relative to the reload40during a stapling procedure.

With reference now toFIGS. 6A-8, adapter assembly30includes an electrical assembly60disposed therewithin, and configured for electrical connection with and between handle assembly20and reload40. Electrical assembly60provides for communication (e.g., identifying data, life-cycle data, system data, load sense signals) with the main controller38of the handle assembly20through the electrical receptacle29.

Electrical assembly60includes the electrical connector32, a proximal harness assembly62having a ribbon cable, a distal harness assembly64having a ribbon cable, a load sensing assembly66, and a distal electrical connector67. The electrical assembly60also includes the distal electrical connector67which is configured to selectively mechanically and electrically connect to a chip assembly (not shown) of reload40.

Electrical connector32of electrical assembly60is supported within the proximal end portion30bof the adapter assembly30. Electrical connector32includes the electrical contacts34which enable electrical connection to the handle assembly20. Proximal harness assembly62is electrically connected to the electrical connector32disposed on a printed circuit board35.

Load sensing assembly66is electrically connected to electrical connector32via proximal and distal harness assemblies62,64. Load sensing assembly is also electrically connected to distal harness assembly64via a sensor flex cable. As shown inFIGS. 6A and 6B, an actuation assembly52, which is coupled to the trocar member50, extends through the load sensing assembly66. The load sensing assembly66provides strain measurements imparted on the adapter assembly30during movement of the trocar member50when coupled to the anvil assembly58during clamping, stapling, cutting, and other mechanical actuations.

For a detailed description of an exemplary powered surgical stapler including an adapter assembly and a reload, reference may be made to commonly owned U.S. Patent Application Publication No. 2016/0310134 to Contini et al., titled “Handheld Electromechanical Surgical System,” filed Apr. 12, 2016, incorporated in its entirety by reference hereinabove.

With reference toFIGS. 9-13, the load sensing assembly66includes a sensor body68having a platform70and a tubular portion72extending from the platform70by a distance “d”. The sensor body68also defines a lumen73through the platform70and the tubular portion72, thereby separating the platform70into a first portion74and a second portion76. The lumen73allows for the passage of the actuation assembly52therethrough. The sensor body68may be formed from any suitable material, such as stainless steel, that allows for the sensor body68to be elastically deformed when stressed. In embodiments, the sensor body68may be fabricated from stainless steel, such as 17-4 stainless steel heat-treated to H-900 standard.

The tubular portion72may have any suitable shape such as cylindrical, faceted, or combinations thereof as shown inFIG. 10. More specifically, the tubular portion72includes a plurality of side walls72ainterconnected by fillet corners72b. The tubular portion72also includes a bottom contact surface72c. The platform70also includes a top (e.g., distal) surface78and a bottom (e.g., proximal) surface80(FIG. 10) as well as a first slot82defined within the first portion74of the platform70and a second slot84defined through the second portion76of the platform70. Slots82and84work in combination with the design of sensor body68to provide uniform bending when loaded. The uniform loading and resulting strain output causes a load sensor circuit86(FIGS. 11 and 12) of the load sensing assembly66to provide provides linear strain output at the first portion74of the platform70, which is measured by a load sensor circuit86secured to the first portion74and covered by a cover88as shown inFIG. 11.

With reference toFIGS. 6A and 6B, the load sensing assembly66is disposed between a support block54and a connector sleeve56. In particular, the tubular portion72of the sensor body68on the bottom contact surface72crests on the support block54and the top surface78of the platform70abuts a proximal end of the connector sleeve56. During operation of the surgical device10, namely, clamping, stapling, and cutting, the sensor body68is elastically deformed (similar to a support beam) in proportion to the forces applied to the support block54and the connector sleeve56. In particular, deflection of the sensor body68applies a force to the load sensor circuit86(FIGS. 11 and 12), which is deformed causing its electrical resistance to increase, which is reflected in its measurement signal. A change in a baseline of the measurement signal is indicative of the forces being imparted on the support block54and the connector sleeve56, which are generally descriptive of the forces encountered during clamping, stapling, and cutting.

With reference toFIG. 16, the adapter assembly30also includes a gimbal81disposed over the tubular portion72. The gimbal81may be formed from any high tensile strength material, such as stainless steel and other metals. The gimbal81has a tubular shape having a width “d”, a thickness “t”, and a radius “r”. The width “d” is substantially equal to the distance “d”. The gimbal81includes a top (e.g., distal) surface83aand a bottom (e.g., proximal) surface83b. Each of the top surface83aand the bottom surface83bhas an undulating shape having one or more waveforms85aand85b, respectively. The waveforms85aand85bmay have a wavelength that is based on the radius “r” of the gimbal81, namely, “πr”, and an amplitude that is substantially equal to the thickness “t” of the gimbal81. Each of the waveforms85aand85bincludes a plurality of peaks87aand87b, respectively.

The gimbal81is disposed between the bottom surface80of the platform70and the support block54. More specifically, the top surface83aof the gimbal81is in contact with the bottom surface80of the platform70and the bottom surface83bof the gimbal81is in contact with a distal surface of the support block54. Since each of the top surface83aand the bottom surface83bincludes the peaks87aand87b, respectively, the peaks87aand87bare in contact with their respective surfaces, namely, bottom surface80and the support block54.

As the load sensing assembly66is compressed between the support block54and the connector sleeve56, the support block54applies pressure on the gimbal81. In additional to longitudinal pressure, lateral movement of the support block54is negated by the gimbal81. This is due to the dual-rocking configuration of the gimbal81due to the top and bottom surfaces83aand83bhaving undulating shapes. In particular, the gimbal81is rotated about the point of contact between the top and bottom surfaces83aand83band the bottom surface80of the sensor body68and the support block54, namely, the peaks87aand87b. Inclusion of two peaks87aand87bon each of the top and bottom surfaces83aand83bprovides for isolation of the sensor body68by preventing off-axis loads, namely, stresses imparted in a plane perpendicular to a longitudinal axis X-X defined by the sensor body68, being measured by the load sensor circuit86. This allows for the load sensor circuit86to measure only the stresses imparted in the longitudinal direction, which provides for an accurate measurement.

In embodiments, the gimbal81may be disposed distally of the sensor body68. More specifically, the gimbal81may be disposed between the connector sleeve56and the top surface78of the sensor body68. Accordingly, the tubular portion72may be disposed on the top surface78rather than the bottom surface80. In a distal configuration, the gimbal81may be disposed around the tubular portion72and functions in the same way as a proximal configuration described above.

In further embodiments, the sensor body68may be disposed between two gimbals81, namely, between the support block54and/or the connector sleeve56. In yet further embodiments, the tubular portion72may be any suitable fixation structure such as a post, a depression, and the like, which would allow for securing of the gimbal81to the sensory body68.

In additional embodiments, the gimbal81may have flat top and bottom surfaces83aand83band the surfaces in contact with the gimbal, e.g., the bottom surface80of the platform70and the distal surface of the support block54, may have an undulating shape having one or more waveforms85aand85b, as described above.

With reference toFIGS. 17 and 18, the adapter assembly30may include a support block154and a sensor body168. The support block154and the sensor body168may be used in lieu of the support block54and the sensor body68and the gimbal81to isolate the sensor assembly66. The support block154includes a convex surface feature, namely, a ridge156having a curved cross-section. The sensor body168includes a counterpart concave surface feature, namely, a curved groove170. The curved groove170is formed on a proximal surface of the tubular portion72. The curved groove170and the ridge156are disposed along a pivot axis Y-Y that is transverse to the longitudinal axis X-X. The curved groove170and the ridge156have substantially the same radius r2such that the ridge156fits within the curved groove170, allowing sensor body168to pivot about the pivot axis Y-Y relative to the support block154. The pivot axis Y-Y passes through a center of an arc defining the ridge156and the curved groove170. The pivoting configuration of the ridge156and the curved groove170provides for isolation of the sensor body168by preventing off-axis loads, namely, stresses imparted in a plane perpendicular to a longitudinal axis X-X that lie on the axis Y-Y, being measured by the load sensor circuit86. This allows for the load sensor circuit86to measure only the stresses imparted in the longitudinal direction, which provides for an accurate measurement of the strain imparted on the adapter assembly30.

With reference toFIGS. 19 and 20, the adapter assembly30may include a support block254and a sensor body268. The support block254and the sensor body268may be used in lieu of the support block54and the sensor body68and the gimbal81to isolate the sensor assembly66. The embodiment ofFIGS. 19 and 20is similar to the embodiment ofFIGS. 17 and 18with the location of the concave and convex surfaces being reversed. In particular, the support block254includes a concave surface feature, namely, a curved groove270having a curved cross-section. The sensor body268includes a counterpart convex surface feature, namely, a ridge256. The ridge256and the curved groove270are disposed along a pivot axis Y-Y that is transverse to the longitudinal axis X-X. The ridge256and the curved groove270have substantially the same radius r2such that the curved groove270fits within the ridge256, allowing sensor body268to pivot about the pivot axis Y-Y relative to the support block254. The pivoting configuration of the curved groove270and the ridge256provides for isolation of the sensor body268by preventing off-axis loads, namely, stresses imparted in a plane perpendicular to a longitudinal axis X-X that lie on the axis Y-Y, being measured by the load sensor circuit86. This allows for the load sensor circuit86to measure only the stresses imparted in the longitudinal direction, which provides for an accurate measurement of the strain imparted on the adapter assembly30.

With reference toFIGS. 21 and 22, the adapter assembly30may include a support block354and a sensor body368. The support block354and the sensor body368may be used in lieu of the support block54and the sensor body68and the gimbal81to isolate the sensor assembly66. The embodiment ofFIGS. 21 and 22is similar to the embodiment ofFIGS. 19 and 20. In particular, the support block354also includes a concave surface feature, namely, a curved groove370having a curved cross-section. In addition, a gimbal181is disposed between the support block354and the sensor body368. The gimbal181includes a counterpart convex surface feature, namely, a ridge356that is disposed on a first contact surface181a. The ridge356and the curved groove370are disposed along a pivot axis Y-Y that is transverse to the longitudinal axis X-X. The ridge356and the curved groove370have substantially the same radius r2such that the curved groove370fits within the ridge356, allowing gimbal181to pivot about the pivot axis Y-Y relative to the support block354.

In addition, the gimbal181also includes one or more concave surface features, namely, a curved groove183having a curved cross-section. The curved groove183is disposed on a second contact surface181b, which is opposite the first contact surface181a. The sensor body368includes a counterpart convex surface feature, namely, a ridge456. The ridge456and the curved groove183are disposed along a pivot axis Z-Z that is transverse to the longitudinal axis X-X and the pivot axis Y-Y. The ridge456and the curved groove183have substantially the same radius r3such that the curved groove183fits within the ridge456, allowing gimbal181to pivot about the pivot axis Z-Z relative to the sensor body368. The dual pivoting configuration of the gimbal181with respect to the support block354and the sensory body368provide for isolation of the sensor body268by preventing off-axis loads, namely, stresses imparted in a plane perpendicular to a longitudinal axis X-X that lie on the Y-Y and Z-Z axes, being measured by the load sensor circuit86. This allows for the load sensor circuit86to measure only the stresses imparted in the longitudinal direction, which provides for an accurate measurement of the strain imparted on the adapter assembly30.

With reference toFIG. 23, another embodiment of a gimbal281is shown. With reference toFIG. 23, the adapter assembly30also includes a gimbal281disposed over the tubular portion72. The gimbal281may be formed from any elastomeric, conformable material such as silicone rubber. Suitable silicone rubbers include room temperature vulcanization (RTV) silicone rubbers; high temperature vulcanization (HTV) silicone rubbers and low temperature vulcanization (LTV) silicone rubbers. These rubbers are known and readily available commercially such as SILASTIC® 735 black RTV and SILASTIC® 732 RTV, both from Dow Corning; and 106 RTV Silicone Rubber and 90 RTV Silicone Rubber, both from General Electric. Other suitable silicone materials include the silanes, siloxanes (e.g., polydimethylsiloxanes) such as, fluorosilicones, dimethyl silicones, liquid silicone rubbers such as vinyl cross-linked heat curable rubbers or silanol room temperature cross-linked materials, and the like. The gimbal81includes a top (e.g., distal) surface283aand a bottom (e.g., proximal) surface283b.

The gimbal281is disposed between the sensor body68and the support block54. More specifically, the top surface283aof the gimbal281is in contact with the tubular portion72of the sensory body68and the bottom surface283bof the gimbal281is in contact with a distal surface of the support block54. As the load sensing assembly66is compressed between the support block54and the connector sleeve56, the support block54applies pressure on the gimbal281. In additional to longitudinal pressure, lateral movement of the support block54is negated by the gimbal281due to its compression.

With respect to embodiments ofFIGS. 17-23, the orientation of the sensory body68, the gimbals181and281, the concave and convex surface features may be reversed may be disposed distally of the sensor body68such that the interface is disposed distally of the sensory body68. More specifically, the concave or convex surface features described above may be formed on the connector sleeve56and the top surface78of the sensory body68rather than the tubular portion72.

With reference toFIGS. 11, 12, and 25, the load sensor circuit86is coupled to a signal processing circuit90, which includes a flexible circuit board92having a contact portion94and a signal processing circuit portion96. The contact portion94is interconnected with the signal processing circuit portion96via a flex strip98and includes a plurality of first pass-through contacts100. The signal processing circuit90includes analog and digital circuit components (e.g., controller130) that are configured to perform signal processing on signals from the load sensor circuit86and output a measurement signal to the handle assembly20.

The flexible circuit board92may be any suitable dielectric multilayer flexible materials, such as PYRALUX® materials available from DuPont of Wilmington, Del., liquid crystal polymer materials, and the like. In embodiments, the flexible circuit board92may include additional dielectric layers, which stiffen the flexible circuit board92so that the solder connections of the components located along the flexible circuit board92are not subjected to unwanted movement due to thermal expansion and/or mechanical movement of the load sensing assembly66. In embodiments, the flexible circuit board92may fabricated in a flat state (FIG. 25) and formed during soldering to sensor body68(FIG. 11). In further embodiments, the flexible circuit board92may be pre-bent using a fixture with or without heat to form the desired shape denoted inFIG. 11.

The contact portion94is configured to couple to the load sensor circuit86, which includes one or more load sensing devices102interconnected by a plurality traces or other conductors. In embodiments, the load sensing devices102may be strain gauges, pressure sensors (e.g., pressure sensing film), or any other suitable transducer devices configured to measure mechanical forces and/or strain and output an electrical signal in response thereto. Signal output is achieved when the load sensing circuit86is bonded to the sensor body68such that the load sensing devices102are positioned in the respective areas of linear strain output when load sensing assembly66is elastically deformed.

The load sensor circuit86may be a single circuit board, such as a flexible circuit board with the load sensing devices102being disposed thereon and electrically interconnected via internal traces. The load sensing devices102are also electrically coupled via traces to a plurality of second pass-through contacts101. In embodiments, the load sensing devices102may be attached to the first portion74of the platform70individually, rather than through the load sensor circuit86and then wired together to provide for electrical coupling.

The plurality of load sensing devices102may be arranged on the load sensor circuit86in a variety of configurations to achieve temperature compensation or other resistor networks, such as a Wheatstone Bridge in which two load sensing devices102are arranged to move in response to tension of the load sensing assembly66and two load sensing devices102are arranged to move in response to compression of the load sensing assembly66. The configuration of four load sensing devices102as shown inFIG. 25provides maximum signal output and temperature compensation and is known as a full bridge circuit.

With reference toFIG. 13, the first portion74also includes a pocket104having a gauging surface106for attachment of the load sensor circuit86and the contact portion94of the signal processing circuit90. In embodiments, the load sensor circuit86may be bonded to the gauging surface106such that the signal processing circuit90outputs the measurement signal in response to the sensor body68. The pocket104also includes a slot108having a plurality of pins110passing therethrough.

The slot108passes through the pocket104to the bottom surface80as shown inFIG. 11. The pins110are electrically coupled to the signal processing circuit90through a plurality of second pass-through contacts101(FIG. 25). In particular, when load sensor circuit86is bonded to the pocket104, the second pass-through contacts101are inserted over pins110. Thereafter the first pass-through contacts100of the contact portion94are also inserted over the pins110. The first and second pass-through contacts100and101are aligned such that after soldering of the pins110thereto, the signal processing circuit90and the load sensor circuit86are electrically coupled to the pins110and each other. In embodiments, there may be four pins110, with two of the pins110acting as communication lines and the remaining two pins110proving electrical power for energizing the load sensor circuit86and the signal processing circuit90. After soldering, the flexible circuit board92can be arranged to fit within the cover88.

In embodiments, the flexible circuit board92may be folded and/or bent as shown inFIGS. 11 and 12. In further embodiments, a support structure112may be disposed within the pocket104. The support structure112includes one or more surfaces114onto which the flexible circuit board92is attached. The support structure112may have any suitable shape such that the flexible circuit board92is conformed to the shape of the support structure112. The flexible circuit board92may be secured to the support structure112in any suitable manner, e.g., bonding, fasteners, etc.

In further embodiments, a wrap116can be disposed over the flexible circuit board92to insulate electronic components of the signal processing circuit portion96and prevent short circuits if the flexible circuit board92contacts an interior surface of the cover88. The wrap116may be polyimide tape or ionomer resin tape, such as KAPTON® and SURLYN®, respectively, from DuPont of Wilmington, Del., shrink-wrap, polyisoprene membranes, low durometer potting compounds, parylene coatings, and other dielectric materials and applications suitable for insulating electronic circuits.

With reference toFIG. 10-13, the pins110are secured within a header118, which hermetically seals the pocket104at the bottom surface80. As shown inFIG. 24, each of the pins110is encased in a glass sleeve120, each of which is then embedded in a peripheral housing122. This construction seals the interior of cover88and the pocket104from the outside once the header118is bonded to slot108at the bottom surface80of the platform. The header118may be bonded (e.g., welded) to the bottom surface80.

A hermetic seal may be formed by inserting the pins110through their respective glass sleeves120, after which the pins110along with their glass sleeves120are inserted into corresponding bores of the peripheral housing122of the header118. The entire assembly of the pins110, glass sleeves120, and the peripheral housing122are heated. Upon heating, the bore of the peripheral housing122, which may be formed from any suitable metal (e.g., stainless steel), expands and the glass sleeves120fill the void. The pins110being formed from metal expand minimally and upon cooling, the glass sleeves120provide compression seals about their respective pins110and bores of the peripheral housing122. As shown inFIG. 8, the pins110are the coupled to a flex cable65, which in turn, is coupled to distal harness assembly64.

With reference toFIG. 13, the pocket104further includes a step124along an entire perimeter of the pocket104. The step124corresponds in size and shape to a flange126of the cover88as shown inFIGS. 14 and 15, to allow for creating of a hermetic seal. In addition, the flange126is configured to fit within the step124and is coplanar with the step124. This allows for the flange126to sit on a flat surface portion of the step124.

The cover88may be formed from a similar material as the sensor body68. The cover88may be secured to the sensor body68in any suitable manner to ensure that the signal processing circuit90is hermetically sealed within the cover88. In embodiments, the cover88and the sensor body68may be formed from a metal, such as stainless steel, and the cover88may be welded (e.g., by a laser) to the platform70around their respective perimeters. The cover88may be manufactured using a deep draw process, which provides for economical manufacturing. In embodiments, the sensor body68and the cover88may be manufactured using any suitable methods such as, machining, metal injection molding, 3-D printing, and the like.

With continued reference toFIGS. 14 and 15, the cover88includes a top wall89, a pair of opposing side walls91aand91b, which are connected by a pair of opposing walls93aand93b. The walls93aand93bmay have an arcuate shape to accommodate the signal processing circuit90. In embodiments, the walls89,91a,91b,93a,93bmay have any suitable shape for enclosing the signal processing circuit90. More specifically, the walls89,91a,91b,93a,93bdefine an inner cavity95, which fits over the signal processing circuit90. The inner cavity95may also enclose the signal processing circuit90in a thermal management material. In embodiments, the inner cavity95may be filled with the thermal management material such as by using pre-metered injectors. The signal processing circuit90, which is attached to the sensor body68, is then inserted into the filled inner cavity95, after which the cover88is secured to the sensor body68as described above. After the cover88is secured, the thermal management material may flow within the cavity95and the pocket104, which is in fluid communication with the cavity95.

With reference toFIGS. 25 and 26, the signal processing circuit90includes a controller130having a storage device132, which may be an electrically erasable programmable read-only memory (“EEPROM”) or any other suitable non-volatile memory device. The controller130may be any suitable microcontroller or any other processor, such as CORTEX® microcontrollers available from ARM of Cambridge, UK. The controller130may include analog-to-digital converters, digital-to-analog converters, timers, clocks, watchdog timers, and other functional components that enable the controller130to process the analog measurement signals from the load sensing devices102. In particular, the controller130is configured to amplify the signal from the load sensing devices102of the load sensor circuit86, filter the analog signal, and convert the analog signal to a digital signal. The controller130is also configured to transmit the digital signal to the main controller38of the handle assembly20, which controls operation of the surgical device10based on the digital signal indicative of the sensed mechanical load.

The controller130is programmable to allow for adjustments to gain and offset parameters for processing the analog signal. In particular, the controller130stores a zero balance value and corresponding gain and offset parameters in the storage device132. After assembly of the load sensing assembly66, load sensor circuit86is calibrated. In embodiments, the load sensor circuit86may be recalibrated periodically to ensure accurate measurements. Calibration may be performed under zero balance, namely, when the load sensor circuit86is unloaded. If the load sensor circuit86is outputting any signal even in an unloaded state, or conversely, not outputting a sufficient signal in response to a loaded state, the controller130is programmed to compensate for such discrepancy. This is accomplished by adjusting gain and offset parameters of the controller130, which allows the controller130to adjust the analog signal to correspond to the zero balance state. The controller130may be programmed through the main controller38, which is coupled to the controller130through the pins110as described above.

It will be understood that various modifications may be made to the embodiments of the presently disclosed adapter assemblies. Therefore, the above description should not be construed as limiting, but merely as exemplifications of embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the present disclosure.