DE102006049378A1 - Implant i.e. electrical passive implant, jointing knee of patient, has passive radio frequency identification unit coupled with deformation sensors, for monitoring sensor value, where sensors are implemented as servicing interface - Google Patents

Abstract

The implant i.e. electrical passive implant (1), has a passive radio frequency identification (RFID) unit (2, 5, 8) coupled with deformation sensors (3, 6, 9) e.g. strain gauges, for monitoring a sensor value. The sensors are implemented as servicing interfaces, where the RFID unit includes an authorization scanning function. An answer signal is sent with sensor information when the authorization code of the RFID unit is detected as effective. An independent claim is also included for a method for selection of sensor characteristic values from a radio frequency identification unit at an implant.

Description

The The invention relates to an implant, in particular an electrically passive Implant.

implants are wear and rejection reactions exposed. It is with electrically passive implants, ie those which have no electrically active control, difficult possible, to query their condition. For status query are known: an operation of the patient for optical assessment; an application an imaging method, but firstly has side effects and secondly often not the required resolution accuracy having; and partly an introduction of electrical cables to the implant.

It It is therefore the object of the invention to provide a simplified, Noninvasive query of the state of an electrically passive implant provide.

These The object is achieved by an implant according to claim 1 and a method solved according to claim 10. Preferred embodiments are in particular the dependent claims alone or in combination removable.

To is the implant with a RFID ("Radio Frequency Identification) unit, So a queryable radio mark, equipped. The RFID unit is connected to a sensor to query a sensor value. When asked The RFID unit is, if necessary, with additional values such as an RFID identifier of the RFID unit emitted from the sensor read sensor value. The RFID unit can be used as passive RFID, ie without power source, be executed which increases the longevity.

By The use of an RFID unit is easy and reliable Noninvasive status inquiry, especially of electrically passive implants to reach. RFID units can also space-saving and thin accomplished what their uses are further enlarged.

RFID units Also called RFID, RFID tag or RFID chip, are for radio query of commercial goods (for example as part of a logistics chain) or services (For example, for theft or so-called ticketing) in general known. An RFID unit typically has a transmitting / receiving unit for radio signals and sends after receiving a request (radio) signal ("ping") over the Transmit / receive unit an answer (radio) signal over the transmitting / receiving unit from, for example, an identifier or stored in RFID and / or value read from this. The present invention includes the embodiment of the RFID unit as it is previously accessible to the skilled person.

Of the Sensor is advantageously a resonant circuit, in which conductive, in particular metallic, parts of the implant part of the resonant circuit form. This can make changes to the metallic parts, such as by wear or tear fatigue arise, be detected because the resonant circuit detuned becomes. For example, a sliding layer is subject to a complete denture at the knee joint of a wear. In case of wear of the intermediate layer the resonant circuit is changed due to the changed impedance. Also a material fatigue the formation of microcracks detunes the resonant circuit.

Of the Sensor may advantageously be another wear sensor, such as a resistance wire integrated into the implant or an integrated therein impedance line, the or when worn thinner and thus becomes high-impedance. The impedance value can - if necessary, for example as the corresponding voltage value or current value - can be read out easily.

Of the Sensor may preferably be a deformation sensor for detecting deformations, in particular a strain gauge to be. The strain gauge changes an impedance value from a change in length.

Of the Sensor can also be a sensor on white blood cells, creating a Degree of rejection sensed in the area of the implant can be, for which is the number of white ones Corpuscles Measure is.

Of the Sensor can - in particular for electric active implants - as Maintenance interface executed be such that circuit parameters detected, read and manipulated can be, like For example, an operating voltage, a reference voltage or an electronic meter reading, z. The number of pulses output by a pacemaker.

Of the Sensor can generally be a vital sensor for vital signs of a patient, so that in particular of damaged organs noninvasive can receive valuable information.

The Implant may also comprise several RFID units with different, also functionally different, sensors are coupled.

It is advantageous for increasing the data security if the RFID unit has an authorization query function, so that the RFID unit only transmits an answering radio signal when a correct authorization code is received via the request radio signal. It is advantageous for the simple design of the RFID unit if the authorization code is a simple identifier. It may be advantageous for increased security while still simplifying the design of the RFID unit if the authorization identifier is a transaction number, TAN. It can all known TAN methods are used, such as. TAN, iTAN, session TAN, challenge-response and so on, as they are known in particular from the banking industry.

Especially suitable is an RFID unit, which has a memory for storing and reading at least one TAN, and a comparison unit to unlock at least one RFID step based on a comparison of a TAN stored in the memory with one over the Transceiver received TAN. Preferably, several are initially TANs ("TAN list") are stored in memory. The comparison unit can thus have the function of an authorization unit fill out.

By Firstly, the use of TANs greatly increases data security, as only the one in possession of a valid TAN is getting access to the master RFID chip. Second, the RFID chip needs just a simple memory and a simple comparison unit instead of an encryption circuit.

Becomes, in a typical application, transmit a TAN to the RFID unit, so the comparison unit will receive the received TAN with a Compare TAN. Do the TANs agree (which is generally not identity TANs, but the fulfillment of a predetermined relationship to each other, z. A mathematical relationship), The RFID chip enables the generation of the instruction sequence.

Preferably is at least one stored in the one RFID unit TAN with a location identifier, z. B. a hospital provided. Is from transmit a date field to the RFID chip, for example with the request radio signal, so the comparison unit next to the actual TAN identifier also compare the date and make an activation dependent on it, whether the transmitted Date is within a permitted range. This is particularly advantageous if to unlock a transmission of a date field is mandatory, since such an unauthorized handling the RFID chip further difficult, in particular, if a date setting in the proposed RFID read / write device by the end user no longer possible is.

On similar Way, at least one stored in memory TAN preferably be provided with a time tag containing a content of a received time field is compared. Is the received time window outside the time slot assigned to the TAN in RFID, there is no activation. In this case, preferably a time setting in the proposed RFID read / write device the end user is no longer possible is.

Especially to prevent handling of the RFID chip by an unintentional RFID read / write device, the at least one TAN stored in memory is preferably provided with an RFID reader / writer identifier, the additional or alternatively for transmission a correct TAN is required for activation.

It can be cheap be if the RFID unit is a means of deleting a TAN after a successful activation by comparison with this TAN. This will increase the number of maximum possible, including unauthorized, Limited actions. Alternatively, after deleting the last TAN one valid from then on permanent identifier can be used, or z. For example, the last one TAN can not be deleted.

Of the Sensor value can either during the query are read by the sensor ("real-time query"), or from a memory of the RFID unit, in which he has been previously filed, possibly together with others Sensor readings.

In the following embodiment An aspect of the invention is schematically illustrated in more detail.

1 shows a sketch of a detail of an implant with several RFID units;

2 shows an X-ray of a hip prosthesis.

In 1 is a partial view of a knee joint implant 1 shown without voltage or power supply. At the knee joint implant 1 is a first RFID unit 2 arranged with a likewise on the knee joint implant 1 arranged first sensor in the form of a superficially integrated into the implant resistance wire or an impedance line 3 through a signal line 4 is coupled.

Upon receipt of a request signal by the RFID unit 1 which has been sent, for example, by a hospital-located reader (not shown), is passed through the RFID unit 1 via the signal connection 4 a sensor reading or be multiple sensor from with the RFID unit 1 connected sensor 3 queried. Thereafter, by the RFID unit 1 a response signal containing the sensor reading sent. The RFID unit has for this purpose a transmitting / receiving device for radio signals (not shown for clarity).

In the embodiment shown, the RFID unit 1 and an authorization request function, in which the received request signal must contain a valid authorization code for sending the response signal with sensor information. This is the RFID unit 1 equipped with a comparison circuit (not shown) which compares the received authorization code with a code stored in the memory (not shown) and when equal (or fulfilling a specified relationship) enables the generation and transmission of the response signal.

At the knee joint implant 1 is also a second RFID unit 5 attached, which also has a knee joint implant 1 attached second sensor in the form of a resonant circuit 6 through a signal line 7 is coupled. The resonant circuit is shown here purely schematically and has at least partially conductive, in particular metallic, parts of the implant 1 on.

At the knee joint implant 1 is also a third RFID unit 8th attached, which also has a knee joint implant 1 attached second sensor in the form of a strain gauge 9 through a signal line 10 is coupled. By tapping the resistance value and / or impedance value of the strain gauge 9 or an associated state value can also be a deformation of the implant 1 getting closed.

Not shown, but possible are further coupled with RFID units sensors, such as a sensor on white Or corpuscles a vitality sensor.

2 shows an X-ray of a hip prosthesis from pan 11 , Head 12 and shaft 13 which can be equipped with RFID tags.

• 1) den Kopf 12 mit einem oder mehreren Widerstandsdrähten (nicht dargestellt) überziehen. Diese Widerstandsdrähte unterliegen dadurch demselben Abrieb wie der Prothesenkopf 12, d.h., mit zunehmendem Abrieb ändert sich die elektrische Impedanz der Drähte, die messbar ist. Aus dieser Messgröße lässt sich dann eine Aussage über den Implantatszustand (Abrieb der Oberfläche des Kopfes 12) ableiten.
• 2) die konkave Fläche der Gelenkspfanne 11 mit einem oder mehreren Widerstandsdrähten überziehen, wobei Wirkung und Messung eines Abriebs analog zum Kopf 12 geschehen kann.
• 3) einen oder mehrere RFID-Chips (nicht dargestellt) auf dem Implantat aufbringen. Es werden vorteilhafterweise jeweils ein Chip auf dem Schaft 13 und ein Chip auf der Pfanne 11 montiert. Danach wird eine Verbindung mit den Widerstandsdrähten hergestellt. Der Chip auf dem Schaft 13 wird hierbei mit den Drähten auf dem Kopf 12 verbunden.

In a hip joint prosthesis stand pan 11 and head 12 in direct contact. The movements of the implant or implant carrier here wear occurs. To the abrasion of the pan 11 and the head 12 For example, you can:

• 1) the head 12 Cover with one or more resistance wires (not shown). These resistance wires are subject to the same abrasion as the prosthetic head 12 That is, as the wear increases, the electrical impedance of the wires, which is measurable, changes. From this measurement can then be a statement about the state of the implant (abrasion of the surface of the head 12 ).
• 2) the concave surface of the joint socket 11 Cover with one or more resistance wires, whereby effect and measurement of an abrasion analogous to the head 12 can happen.
• 3) apply one or more RFID chips (not shown) to the implant. There are advantageously one chip each on the shaft 13 and a chip on the pan 11 assembled. Thereafter, a connection is made with the resistance wires. The chip on the shaft 13 This is done with the wires on the head 12 connected.

• – Verformungen des Implantats durch gezielte Platzierung von Dehnungsmessstreifen (DMS) auf dem Implantat. Die Auswerteschaltung auf dem RFID-Chip muss bei Verbindung an einen DMS entsprechend angepasst werden.
• – die Kräfte, die auf das Implantat einwirken. Auf dem Implantat werden elektrische Schwingkreise (nicht dargestellt) platziert. Die mechanischen Kräfte, die auf das Implantat einwirken, bewirken Veränderungen in der Schwingkreisgeometrie und dadurch eine Verschiebung der Resonanzfrequenz. Dieser Effekt kann dann durch eine Messschaltung erfasst werden. Die hier zum Einsatz kommenden RFID-Tags weisen vorteilhafterweise folgende Eigenschaften auf: a) um ein Auslesen im Inneren des Körpers zu ermöglichen, kommen Hochfrequenz (HF)-Tags zum Einsatz. b) die Tags werden mit einem Sensorinterface (für z.B.: Widerstandsdrähte) versehen. Teil dieses Interfaces ist im konkreten Fall eine Schaltung zur Messung der elektrischen Impe danz der Drähte. c) sowohl der Tag als auch die angeschlossene Antenne müssen biokompatibel sein.

In addition, further information about the implant can be obtained, e.g. For example:

• - Deformation of the implant by targeted placement of strain gauges (DMS) on the implant. The evaluation circuit on the RFID chip must be adapted accordingly when connected to a DMS.
• - The forces acting on the implant. On the implant electrical oscillating circuits (not shown) are placed. The mechanical forces acting on the implant cause changes in the resonant circuit geometry and thereby a shift in the resonant frequency. This effect can then be detected by a measuring circuit. The RFID tags used here advantageously have the following properties: a) High-frequency (HF) tags are used to enable read-out inside the body. b) the tags are provided with a sensor interface (eg for resistance wires). Part of this interface is in this case a circuit for measuring the electrical impedance of the wires. c) Both the tag and the connected antenna must be biocompatible.

The RFID tags can z. B. be enclosed with glass. The antennas can z. B. consist of biocompatible materials and implant parts vapor-deposited or glued. Alternatively, the complete execution RFID tag and antenna made of non-biocompatible materials; applied to the one biocompatible protective layer (eg of proteins) becomes.

Of course it is the invention is not limited to the embodiments shown in more detail limited. For example, an implant may have a different number of RFID units exhibit. Also, an RFID unit can be connected to multiple sensors be. In addition, you can other sensors are used.

1

implant

2

RFID unit

3

sensor

4

signal connection

5

RFID unit

6

sensor

7

signal connection

8th

RFID unit

9

sensor

10

signal connection

11

pan

12

head

13

shaft

Claims (12)

Implant, in particular electrically passive implant ( 1 ), characterized in that the implant ( 1 ) at least one RFID unit ( 2 . 5 . 8th ), which is used to query a sensor value with a sensor ( 3 . 6 . 9 ) is coupled. Implant according to claim 1, in which the sensor is a resonant circuit ( 6 ) is, of the conductive, in particular metallic, parts of the implant ( 1 ) form a part. Implant according to claim 1 or 2, in which the sensor inserts into the implant ( 1 ) integrated resistance wire ( 3 ). Implant according to one of claims 1 to 3, in which the sensor comprises a deformation sensor, in particular a strain gauge ( 9 ) is. Implant according to one of claims 1 to 4, wherein the sensor a sensor on white blood corpuscle is. Implant according to one of claims 1 to 5, wherein the sensor designed as a maintenance interface is. Implant according to one of claims 1 to 6, wherein the sensor a vital sensor is. Implant ( 1 ) according to one of claims 1 to 7, in which the RFID unit ( 2 . 5 . 8th ) has an authorization request function in which a received request signal contains an authorization code, wherein when the authorization code from the RFID unit ( 2 . 5 . 8th ) is recognized as valid, a response signal is sent with a sensor information, otherwise not. An implant according to claim 8, wherein the authorization query function an authorization code in the form of a transaction number, TAN, queries. Method for reading sensor characteristics from an implant ( 1 ) arranged RFID unit ( 2 . 5 . 8th ), characterized in that it comprises the following steps: - receiving a request signal by the RFID unit ( 2 . 5 . 8th ); - Readout, by the RFID unit ( 2 . 5 . 8th ), one sensor reading or multiple sensor readings from one with the RFID unit ( 2 . 5 . 8th ) connected sensor ( 3 . 6 . 9 ); Sending out a sensor signal containing the response signal by the RFID unit ( 2 . 5 . 8th ). A method according to claim 10, characterized in that at least one sensor measured value in a memory of the RFID unit ( 2 . 5 . 8th ) is stored. A method according to claim 10 or 11, characterized in that an authorization code is received with the request signal, the method additionally comprising the following steps: - receiving, with the request signal, an authorization code; - Check the authorization code by the RFID unit ( 2 . 5 . 8th ); - Enable the response signal with a valid authorization code.