Beginning in our July/August double sized edition of Elektor, we published the first of our three part project on building an electrocardioscope that uses an Android tablet or smartphone as a wireless terminal for viewing the electrocardiograms. The project involves skillfully combining a small PIC interface to control an analog input stage with a great deal of software.
Making use of technology first invented by Willem Einthoven, we’ve developed an application that’s instructive, fascinating and potentially useful to everyone. Traditionally, electrocardioscopes are cumbersome, frail machines energized from conventional AC power outlets. Being able to perform your own electrocardiograms allows you to monitor the mechanical function (and possible dysfunctions) of a heart. An excellent tool for anyone interested in monitoring their personal health or developing a greater understanding of human biology or cardiology.
In anticipation for the final installment of this project, we’ve released an ECG interface in the form of a ready-to-use module which only requires the addition of four electrodes and an Android application (for smartphone or tablet). As it uses Bluetooth communication, there’s no physical connection between this terminal and its interface.
• Interface for Android phones or tablets with Bluetooth
• Simultaneous or individual scrolling display of the three standard leads (DI, DII, and DIII) and the three enhanced leads (aVR, aVL, and aVF)
• Adapts automatically to screen resolution
• Measures and displays cardiac rhythm
• Audible heartbeat indication
• Scrolling speeds: 250/125/62.5 and 31.25 pixels per second
• Display gain: ×1 ×1.2 ×1.5 ×2 ×3 and ×10
• Full-scale sensitivity: 3.2 mV. 10-bit conversion
• Sampling frequency: 2 kHz
• Common-mode rejection: > 100 dB
• Max. contact voltage: ± 150 mV
• Auto-adaptive alignment time constant
• Frequency response: 0.005 Hz to 170 Hz
• Dynamic trace memory: 10 minutes
• ECG recording in flash memory (10 min)
• Periodic injection of 1 mV/2 Hz calibration signal
• Powered by 2 no. 1.5 V primary or 1.2 V rechargeable cells
• Constant display of battery voltage
• Current consumption: 50 mA (standby: <4 μA)
• Battery life: 15 hours (1 Ah cells)
We’re offering a 10% discount when you purchase the finalized circuit board from our Elektor PCB Service!