Fig 1. The Plessey Semiconductors PS25101 EPIC sensor comes in the same metal or plastic disc style probe assembly that was used for the demonstration systems. The PS25201 has a more compact package for surface-mount assembly onto a PCB.
Fig 2. Patients simply hold one dry-contact EPIC sensor in each hand. An oscilloscope can measure the sensor’s output.
Plymouth, U.K.: Plessey Semiconductors is now sampling its electric potential integrated circuit (EPIC) sensors, with the first samples optimised for use as an electrocardiogram (ECG) sensor. According to Plessey, these products provide resolution that’s as good as or better than conventional ECG electrodes.
EPIC sensors are dry contact, as no gels or similar fluids are required. The patient can simply hold one sensor in each hand. This is very quick to set up, unlike the current approach that requires seven or more leads to be carefully applied to specific locations on the body whilst the patient lies down. Also, EPIC sensors can be easily cleaned between uses, while conventional ECG sensors have to be disposed of after every use at a cost of $2 a set.
These potential sensors are so sensitive that Plessey speculates new ways of taking ECG measurements may be possible, such as building the sensor into a stretcher for immediate monitoring of the patient’s heart rate and respiratory action, or even built into clothing to monitor stress levels in emergency response personnel such as firemen.
As the sensors are very compact and the detection circuitry requires very low power, the EPIC sensor opens up the opportunity for ECG monitoring over a long period of time so abnormalities can be picked up during normal activities without the stress of being in a hospital.
EPIC is offered in two package formats. The PS25101 is supplied in the same custom engineered, metal or plastic disc style probe assembly that was used for the first prototype sensors and demonstration systems (Fig. 1). It comes complete with a connecting lead and DIN plug termination.
The PS25201 is an ultra-high impedance sensor supplied in a more compact custom package with four exposed balls for surface-mount assembly onto the printed-circuit board (PCB) of a customer’s equipment design. It measures 10 mm square and 3 mm high.
Because of the large coupling capacitance of the human body of around 250 pF, the EPIC sensor can be used to obtain true ECG signals by detecting the potential at surface of the skin, which is typically 1 mV p-p (Fig. 2). These sensors are designed for use in high-reliability medical applications and, if required, can be built with an anodised titanium electrode.