Bioimpedance sensor-integrated capsule for monitoring
The present disclosure describes various aspects of various devices, and methods of making and using the devices, for measuring bioimpedance of tissues within a patient's body, such as GI tract tissue. The devices entail using various implementations of capsules or other housings that allow for ingestion or other insertion into a body of the device, equipped with microfabricated sensors and embedded circuitry enabling wireless communication. Among other benefits, this approach addresses a gap in conventional GI tract monitoring devices and methods to non-invasively access the small intestine and directly measure the inflammatory state of intestinal tissue, including ischemia, edema, and mucosal abnormalities. The device integrates 1) bioimpedance measurements resulting from transmural contact of tetrapolar electrodes against intestinal tissue; 2) a packaging scheme for molding the electronics in a biocompatible polymer/resin and conformally wrapping the sensor on the surface of the capsule; and 3) a circuit configuration for signal acquisition and real-time wireless transmission to an external receiver.
1 . A device comprising:
a capsule configured to be ingested by a patient and traverse a patient's gastro-intestinal tract, the capsule comprising:
a processing circuit;
a power source connected to provide power to the processing circuit;
a bioimpedance sensor comprising four disk-shaped electrodes arranged on a flexible substrate that is contoured around a curved side outer surface of the capsule, the bioimpedance sensor being in electrical communication with the processing circuit through a single opening formed in the curved side outer surface of the capsule to provide a bioimpedance signal to the processing circuit measured by the four disk-shaped electrodes; and
a transmitter connected to wirelessly communicate data from the processing circuit outside a patient's body while the capsule is traversing the patient's gastro-intestinal tract.
2 . The device of claim 1 , wherein the single opening is dimensioned to connect the bioimpedance sensor to an interior port oriented radially.
3 . The device of claim 2 , wherein the four disk-shaped electrodes include a pair of outer electrodes configured to inject current and a pair of inner electrodes configured to sense voltage.
4 . The device of claim 3 , wherein each of the four electrodes has a diameter ranging from about 0.5 mm to about 2 mm.
5 . The device of claim 3 , wherein a spacing between inner electrodes of the pair of inner electrodes is between 0.001 mm and 10 mm.
6 . The device of claim 1 , wherein the four disk-shaped electrodes are aligned, on said flexible substrate, parallel to a z-axis of the device that extends along a length of the capsule.
7 . The device of claim 1 , wherein the bioimpedance sensor is configured to measure, with the use of electrical excitation signals at an interrogation frequency ranging from about 1 kHz to about 10 kHz generated inside the capsule, a bioimpedance derived from both extracellular and intracellular spaces of a tissue in contact with said four disk-shaped electrodes.
8 . The device of claim 1 , wherein the processing circuit includes a potentiostat integrated analog-front end circuit and a Bluetooth® Low Energy microcontroller, wherein the Bluetooth® Low Energy microcontroller is configured to interface the bioimpedance sensor with an external receiving device, and wherein the potentiostat is configured to amplify an output current of the bioimpedance sensor.