TiSense Implantable MEMs Sensor

About TiSense

From an innovation perspective, we offer something greater than our standard catheter-based offerings, which currently range from 7-29 days of use. This module is ISO 10993 compliant and is extremely versatile - tailored to each customer’s unique use case or application.

A 3D rendering of the TiSense implantable mems sensor

Schematics of Millar's TiSense implantable mems sensor

Product Features

Module Configuration and Technical Information

TiSense is a MEMS piezo-resistive sensor module filled with silicone oil, communicating pressure from a thin membrane in front. All body contacting portions are constructed from titanium, the pins from the feedthrough are platinum-iridium. TiSense measuring system respects internal vacuum pressures.

Note: Care should be taken when soldering wires on pins to prevent heat damage. It is recommended to use a flex PCB to terminate the pins.

TiSense Applications

TiSense can be used in various medical contexts like chronic heart failure and hydrocephalus, allowing for accurate, dynamic pressure measurements.

Example Clinical Applications

Chronic Heart Failure1

See Chronic Heart Failure

Chronic Heart Failure

Suited for exposure to millions of pressure cycles, TiSense enables devices that can be placed at various points in the heart, offering readily available pressure data.

Hydrocephalus2

See Hydrocephalus

Hydrocephalus

Paired with a shunt system, TiSense aids in managing CSF pressure to a desired value, enabling continuous measurement of intracranial pressure.

Intra Ocular Pressure3

See Intra Ocular Pressure

Intra Ocular Pressure

With a minimal height profile, TiSense is suited for long-term implantation in the inner eye, interfacing with a hermetic implant that houses signal conditioning electronics.

A diagram of the human body highlighting the heart

TiSense Drift Over Simulated Time of 4 years (160 Million Cycles. Click to view Larger version

Drift Testing

The long-term accuracy and stability of TiSense’s output over time has been assessed and quantified by an ongoing reliability drift test. TiSense is subjected to 80/120 mmHg sinusoidal-wave pressure cycles inside an environment filled with water at 37 °C for simulating conditions within the human body. After every 20 million cycles (approximately one week) the pulsatile tester is stopped for collecting the drift data. The graph represents the drift over 13 weeks where TiSense was subjected to over 160 million pressure cycles which is equivalent to 4 years of life in the human body.

Specifications

Sensor Operation Specification
Parameter	Min	Typical	Max	Units	Notes
Operational Pressure Range	510		1010	mmHga	Range IS +/-250 mmHg centered around atmospheric pressure (760 mmHGA). There can be +/-15 mmHg variation in atmospheric pressure at the time ot characterization.
Accuracy Error	-0.5		0.5	% (of applied pressure)	Includes errors from non-linearity over a range of 500 mmHg applied pressure.
Warm-up Time		1		Hour	Final implanted temperature range.
Electrical Specifications
Resistance	2.2	3.2	4.2	KΩ	Resistance of each sensing element as measured from C-A pin or C-P pin
Excitation Range	1		6	Volts DC
Sensitivity of Sensor		10			μV signal per volt of excitation per mmHg incident pressure. When completed with equivalent 3K resistors into a full bridge.
Mechanical Specifications
Height of Module	1.57	1.7	1.83	mm	Pin length not included
Diameter of Module	3.87	4	4.13	mm
Material	Titanium Grade 2
Number of Pins	3
Environmental Specifications
Operational Temperature Range	35	37	39	deg.C
Storage Temperature Range	20		40	deg.C	Storage range until further testing is performed.