What is EPIC?
EPIC is an acronym for "Electric Potential Integrated Circuit" but the term has become synonymous with the integrated circuit technology, the sensor itself, and, in a wider context, the physical principles of operation of the device within a system.
EPIC is a noncontact electrometer, meaning that there is no direct DC path from the outside world to the sensor input, a condition that is somewhat analogous to the gate electrode of an MOS transistor. The electrode is protected by a capping layer of dielectric material to ensure that the electrode is isolated from the body being measured. The device is AC coupled with a lower corner frequency (-3dB) of a few tens of MHz and an upper corner frequency above 200 MHz. This response is adjustable and can be tailored to suit a particular application. Such an electrometer cannot be DC coupled because the Earth's electric field close to the surface is ≈100-150 V/m.
In single-ended mode the device can be used to read electric potential; used in differential mode it can measure the local electric field; or it can be deployed in arrays to provide spatial potential mapping (locating a conducting or dielectric material placed within free space).
- The integrated circuit provides a unique high impedance amplifier design
- The PCB hybrid solution includes EPIC chip, tuning circuit and the sensor electrode
A great amount of interest has been generated within the medical community where the primary focus is on using EPIC for surface body electrode physiology applications such as electrocardiograph (ECG), electromyograph (EMG), electroencephalograph (EEG), and electrooculargraph (EOG).
Because of EPIC's mode of operation, it can be used to detect any disturbance in the local electric field at distances of up to several tens of meters. The human body, because it acts as a large container of conducting/polarizable material, causes a large perturbation in the electric field and so presents an easily detectable target for the sensor. Sitting a few meters away from the sensor, one has only to raise the sole of one's foot to create a strong signal. Arrays of sensors can be used to provide spatial resolution and therefore the location of a target. Such arrays can also distinguish between humans and quadrupeds because the time signature of the response is a direct function of cadence. Such a system of sensors could perhaps be used for border security in remote areas.
The ability of EPIC to resolve signals unique to various muscles or groups of muscles presents opportunities for improved man-machine interaction. For example, a quadriplegic who currently depends on either a unicorn stick or a suck/blow tube to issue commands to equipment within his or her local environment could achieve a faster and more efficient interaction using EPIC for eye tracking and detection of activity in any muscle groups still under voluntary control. Alternatively, because EPIC can assign a unique signature to the use of certain muscle groups, it opens up many possibilities for interfacing with and controlling prosthetic limbs.
EPIC is also a useful tool in the microscopic domain. Small sensors scanning a microchip, for example, can show areas of high or low potential, allowing the user to map the current distribution within metal tracks and other circuit elements. Faults in dielectric materials can also be detected either by passive means (by detecting piezoelectric effects) or by identifying leakage paths in an active circuit.
- Sports Fitness - Plessey launches a sports watch with ECG monitoring capabilities which is Bluetooth 4.0 compatable
- Communications - smart-phones and tablets for ECG and proximity sensing
- Consumer - remote sensing controllers for video games consoles
- Automotive - alertness, occupancy and slow speed collision avoidance