The number of electrodes depends on the intended application. For vital sign monitoring (e.g. ECG and/or respiratory function) the electrode section typically includes at least three electrodes including a first, a second electrode, and a reference electrode that are spaced in a longitudinal direction over the belt. The area between the electrodes and up to 20 mm besides a hart line of the outermost most electrodes is referred to as the electrode portion. Of course the belt can be fitted with a different number of electrodes or different sensors such as a temperature sensor.

The electrode portion and at least a fitting portion extending towards a first terminal end of the belt are generally wrapped around the body of the patient. The belt generally also includes a so-called tail section extending to a second terminal end of the belt (opposite the first). The tail section generally comprises means, e.g. holes, that cooperate with a matching means at the fitting portion to fit the belt around the body (e.g. torso). A remaining portion of the tail can comprise a connector for readout of electrode signal(s). This portion generally remains free during use (not wrapped around the body). Because the belt is elastic, stretchable, a snug, yet comfortable fit around a part of the body (e.g. abdomen of the baby) may be realized. It will be appreciated that the belt can be provided in a number of different sizes, e.g. lengths tuned in accordance with a size category of the baby.

FIG. 1 schematically illustrates a monitoring system comprising a belt 1 in accordance with an embodiment of the present invention. The system comprises a wearable device 1, embodied as a belt to be worn around an abdominal part of the body 100 of a preterm baby. It is not essential that the wearable device is embodied as a belt 1, and in principle the wearable device 1 may be embodied differently, for example as a harness. The wearable device in accordance with the invention includes or provides a carrier, here the belt 1, to the electrodes and other components.

Hereafter, it will be assumed that the wearable device is embodied as a belt, and that the belt itself is the carrier. Therefore, the terms ‘carrier’ and ‘belt’ may sometimes have been interchanged in the text and be referred to by the same reference numeral.

The belt comprises a plurality of electrodes 8 that make contact with the skin of the baby 100. The electrodes 8 receive electric physiological signals from the body 100 of the baby, in particular from the muscles from which the respiratory signal may be obtained, and from the heart of the baby. The system further comprises one or more electronic units configured for reading out, processing, and displaying and/or recording, electric physiological signals from the one or more sensor comprised in the belt.

The belt is connected to a sensor unit 40. This unit receives the electric physiological signals from the electrodes 8, and amplifies these using amplifier circuitry 41. The sensor unit 40, from the signals received from the electrodes 8, generates a sensor signal. The sensor signal is transmitted to a receiver unit 50, which processes the signal, and provided to a monitor unit 60 for presentation on a display 62.

The sensor signals from the sensor unit 40 will be transmitted wirelessly, via wireless signal S, to the receiver unit 50. To this end, the sensor unit 40 comprises a data communication unit 42. Similarly, the receiver unit 50 likewise comprises a data communication unit 56. For example, the communication units 40 and 50, may be configured for enabling data communication via Bluetooth low energy. However, alternative data communication protocols may likewise be applied by the units 42 and 56. The receiver unit 40 further comprises a processor 51 that is configured for processing the sensor signals and provide vital signs signals to the monitor 60. The processor may apply certain algorithms that are stored in a memory of the receiver module to perform this task.

The receiver unit 50 is connected to that monitor 60 using a third connector 52 which is received in a cradle or fourth connector 61 in the monitor unit 60. As mentioned herein before, dependent on the embodiment, the receiver unit may be connected in a different way to the monitor 60. For example, the receiver unit 50 may have a wired connection and a plug that connects to a socket in the monitor 60. The receiver unit 50 may alternatively apply wireless communication to the monitor 60 in yet a different embodiment, without departing from the present invention. Also, in a preferred embodiment, receiver unit 50 may be integrated into the monitor 60, e.g. via the cradle 61.

The monitor 60 comprises a display 62 in which the vital sign signals are presented, for example to the medical staff. For example, the monitor unit 60 may present an ECG signal 63 and a respiratory signal 64.

The connection between the belt 1 and the sensor unit 40 is provided via a connector assembly 30. The connector assembly consists of a first connector 31 and a second connector 32 that are complementary to each other, in the sense that they are cooperatively shaped to enable a tight mechanical and electrical connection. The electric physiological signals from the electrodes 8 are provided to the first connector via a conductive path. As seen more clearly in FIGS. 2, 5, and 7, the conductive path is provided by an electric circuit, wiring 16, carried or provided by the flex-PCB 10. The flex PCB includes a carrier substrate 10s that is sufficiently flexible for the flexible belt. The carrier substrate is typically formed by a flexible plastic substrate. The substrate can e.g. be polyimide, polyether ether ketone (PEEK) or polyester film. In a preferred embodiment, the carrier substrate is formed by polyimide (e.g. as commercially available under the name Kapton®—DuPont). A dielectric cover layer 10c covers the wiring opposite the carrier substrate. The dielectric cover layer comprises, or is essentially formed of, a plastic dielectric composition. The composition can be similar or the same as the carrier substrate, E.g. polyimide, PEEK or polyester. The cover layer preferably has a thickness ≤70 μm. Typically in a range between 20 and 70 μm, e.g. about 25-45 μm. Thicker layers would negatively affect belt flexibility and/or stretchability and thus wearer comfort. The flex-PCB as a whole, including carrier, wiring, cover layer and optional adhesive layers preferably has a thickness ≤500 μm, typically 225-500 μm, e.g. 285±50 μm.

FIG. 2 provides a schematic partial a cross-section side view of an embodiment of the present invention at the electrode portion. The electrode 8 is mounted on a flex-PCB 10. As best seen in FIGS. 6-7, the flex-PCB includes the wiring for readout and a dielectric cover layer 10c that covers the wiring opposite the carrier substrate 10s. Together the substrate 10s and cover 10c provide a first barrier structure 21 that encapsulates the wiring 10. The belt is further provided with a secondary barrier structure 22