Methods and systems relating to biological systems with embedded mems sensors
Small implantable silicon-based devices offer an ability to revolutionize the management of trauma victims. For example, implantable pressure sensors allow the devastating outcomes of compartment syndrome to be minimized through continuous or periodic monitoring whilst being compatible with the ongoing drives to increase out-patient care and reduced hospitalization time. Further, small implantable silicon-based sensor microsystems according to embodiments of the invention whilst being capable of measuring pressures under diverse conditions are easily used by nurses in hospital settings as well as also being easily deployed by paramedical personnel in cases of accidents, natural disasters, war, etc. Beneficially, the implantable sensor microsystem will not interfere with movement of the patient during stabilization, surgery, intensive care stay, outpatient management, etc.
1. A pressure sensor device at least partially implantable into a body, comprising:
a flexible circuit having a first surface and a second surface opposite the first surface, the flexible circuit being provided with at least one opening extending between the first surface and the second surface;
an antenna for at least transmitting data;
at least one pressure sensor mounted on the first surface of flexible circuit over a respective one of the at least one opening of the flexible circuit for measuring a pressure within the body, the measured pressure being coupled to the at least one pressure sensor through the respective one of the at least one opening of the flexible circuit;
a wireless interface circuit connected to the antenna and the at least one pressure sensor, the wireless interface circuit for transmitting a signal indicative of the measured pressure via the antenna;
an encapsulant deposited over at least a portion of the at least one pressure sensor and a portion of the flexible circuit including the first surface and excluding the second surface of the flexible circuit; and a flexible coating encapsulating at least the at least one pressure sensor and the encapsulant.
2. The pressure sensor device of claim 1 , wherein the wireless interface circuit is adapted to convert an incoming wireless signal received by the antenna into electrical power for powering the pressure sensor device.
3. The pressure sensor device of claim 1 , further comprising a battery for powering the pressure sensor device.
4. The pressure sensor device of claim 1 , wherein the at least one pressure sensor comprises at least one pressure sensing element and at least one reference pressure element, and the measured pressure corresponds to an absolute pressure.
5. The pressure sensor device of claim 4 , wherein the absolute pressure is determined based upon the capacitances of the at least one pressure sensing element and the at least one reference pressure element.
6. The pressure sensor device of claim 1 , wherein the at least one opening is filled with the flexible coating.
7. The pressure sensor device of claim 1 , wherein the encapsulant comprises a biocompatible material.
8. The pressure sensor device of claim 1 , wherein the encapsulant is made of one of an epoxy and a thermoplastic adhesive.
9. The pressure sensor device of claim 1 , wherein the at least one pressure sensor comprises at least one microelectromechanical systems (MEMS) pressure sensor.
10. The pressure sensor device of claim 1 , wherein the flexible circuit is made of a polyimide material.
11. The pressure sensor device of claim 1 , wherein the flexible coating is biocompatible and made of an elastomer material.
12. The pressure sensor device of claim 11 , wherein the elastomer material comprises polyether ether ketone (PEEK).
13. The pressure sensor device of claim 1 , wherein the antenna and the wireless interface circuit are mounted on the flexible circuit.
14. The pressure sensor device of claim 13 , wherein the flexible coating further encapsulates the antenna and the wireless interface circuit.
15. The pressure sensor device of claim 1 , comprising a first portion and a second portion, the flexible coating encapsulating only the first portion, the first portion comprising the at least one pressure sensor, the encapsulant and the flexible circuit and the second portion comprising the antenna and the wireless interface circuit.
16. The pressure sensor device of claim 15 , further comprising a tail comprising electrical connections for connecting together the first and second portions.
17. The pressure sensor device of claim 1 , further comprising a layer of silicone gel located between the at least one pressure sensor and the flexible coating.
18. The pressure sensor device of claim 1 , wherein the antenna is operable over a predetermined wireless frequency range which is compatible with a wireless system operating according to a predetermined standard, the predetermined standard being at least one of radio frequency identification and near field communication.
19. The pressure sensor device of claim 1 , wherein the wireless interface circuit is further adapted to transmit, along with the measured pressure, a unique identification code for the pressure sensor device stored within the wireless interface circuit.
20. The pressure sensor device of claim 1 , wherein a thickness over the at least one pressure sensor is below a predetermined thickness to reduce a responsivity of the at least one pressure sensor by a predetermined amount relative to an unencapsulated pressure sensor.