SYSTEM FOR TRANSFERRING INFORMATION BETWEEN AN IMPLANT AND AN EXTERNAL DEVICE
For communicating information between a medical implant in a patient's body and an external communication unit ( 9 ) located outside the patient's body the medical implant is connected to or comprises an internal communication unit ( 11 ). The external communication unit and the internal communication unit communicate with each other using part of the patient's body as a communication path, in particular as an electrical signal line. The communication path between the receiver and the external energizer can be established using a capacitive coupling, i.e. the information can be capacitively transferred over a capacitor having parts ( 1, 3 ) located outside and inside the patient's body.
1 . A system for communication of information comprising
a medical implant for implantation in a patient's body, and
an external communication unit arranged outside the patient's body,
the information being communicated between the medical implant, when implanted in the patient's body, and the external communication unit, wherein
the external communication unit has a part adapted to be in contact with or be placed in a close vicinity of the patient's body when in use,
the medical implant is connected to or comprises an internal communication unit, and
the external communication unit and the internal communication unit communicate with each other using part of the patient's body as a communication path or as an electric signal line,
characterized in that the communicated information is digitally represented as transitions of a signal, in particular as transitions between states or levels of a signal such as between two states or levels, or as variations of the derivative of a signal.
2 . The system according to claim 1 , wherein, in representing the communicated information, Manchester encoding is used.
3 . The system according to claim 1 , wherein, in representing the communicated information, the states of a signal include different frequencies of a signal.
4 . The system according to claim 1 , wherein each of the external communication unit and the internal communication unit include a capacitor plate that is divided into two separate portions, the two separate portions having circular symmetry such as having an outer circular shape or having the shape of circular rings, the two separate portions being concentric with each other.
5 . The system according to claim 1 , wherein each of the external communication unit and the internal communication unit include a capacitor plate that is electrically connected to driver circuits, the driver circuits of the external communication unit and the driver circuits of the internal communication unit having a common electrical ground potential.
6 . The system according to claim 5 , wherein the driver circuits of the internal communication unit include or are connected to an electrically conducting portion, such as a plate or electrode, to be in electrical contact and connection with internal body tissues when implanted and the driver circuits of the external communication unit include or are connected to an electrically conducting portion, such as a plate or electrode, arranged to be electrically attached and connected to the skin of the person's body.
7 . The system according to claim 6 , wherein the electrically conducting portion of the driver circuits of the internal communication unit is or is part of a housing for these driver circuits.
8 . The system according to claim 1 , wherein the communicating of information between the internal communication unit and the external communication unit comprises communicating using electrical signals and the communication path between the internal communication unit and the external communication unit via part of the patient's body has a relatively high electrical resistance to reduce the electrical current flowing in the patient's body.
9 . The system according to claim 8 , wherein the electrical resistance is at least 1 MΩ.
10 . The system according to claim 1 , wherein the communicating of information between the internal communication unit and the external communication unit comprises communicating using electrical signals and the communication path is established using capacitive coupling so that the communication system communicates using the capacitive coupling.
11 . The system according to claim 10 , wherein the internal communication unit comprises a communication transceiver comprising a part of a capacitive energy storage, and wherein the communicating of information using the capacitive coupling includes that an electrical current is injected into or is drawn from the capacitive energy storage.
12 . The system according to claim 10 , wherein the external communication unit comprises a communication transceiver comprising a part of a capacitive energy storage, and wherein the communicating of information using the capacitive coupling includes that an electrical current is injected into or is drawn from the capacitive energy storage.
13 . The system according to claim 10 , wherein the internal communication unit comprises a communication transceiver comprising a first part of a capacitive energy storage, the external communication unit comprises a communication transceiver comprising a second part of the capacitive energy storage, and wherein the communicating of information using the capacitive coupling includes that an electrical current is injected into or is drawn from the capacitive energy storage.
14 . The system according to claim 13 , wherein each of the first and second parts of the capacitive energy storage is divided into two separate portions, arranged so that when an electrical current is injected into or is drawn from the one of the two separate portions, an electrical current is simultaneously drawn from or injected into, respectively, the other of the two separate portions.
15 . The system according to claim 11 , wherein the communicated information is represented by variations of the derivative of the voltage over the capacitive energy storage.
16 . The system according to claim 1 , wherein
each of the external communication unit and the internal communication unit comprises a comparator for comparing at least two different received frequencies,
the external communication unit or the internal communication unit sends out at least two different frequencies, and
a communication path is established in digital form between the external communication unit and the internal communication unit using the different frequencies and said comparator placed at the other end of the communication path.
17 . The system according to claim 1 , wherein the external communication unit comprises a wristwatch or is included in a wristwatch.
18 . A system for communication of information between a medical implant implanted in a patient's body and an external communication unit arranged outside the patient's body, wherein
the external communication unit has a part adapted to be in contact with or be placed in a close vicinity of the patient's body when in use,
the medical implant is connected to or comprises an internal communication unit, and
the external communication unit and the internal communication unit communicate with each other using part of the patient's body as a communication path or as an electric signal line.
19 . The system according to claim 18 , wherein each of the external communication unit and the internal communication unit include a capacitor plate that is divided into two separate portions, the two separate portions having circular symmetry such as having an outer circular shape or having the shape of circular rings, the two separate portions being concentric with each other.
20 . The system according to claim 18 , wherein each of the external communication unit and the internal communication unit include a capacitor plate that is electrically connected to driver circuits, the driver circuits of the external communication unit and the driver circuits of the internal communication unit having a common electrical ground potential.
21 .- 22 . (canceled)