Our body is a sensitive system. At some situations, doctors can’t easily detect diseases and hence it becomes too late to cure it. Use of electronic pill helps us to easily detect the diseases and can take sudden action against it. In 1972, Professor John Cooper and Dr. Eric Johannessen from Glasgow University, U.K has led to the development of electronic pill. It is a medical monitoring system. Measurement parameters of electronic pills include temperature analysis, pH measurements, conductivity and dissolved oxygen. And they can also capture images and sent it into a system. Electronic pills are swallowable. It has a 16mm diameter, a length of 55mm and 5gram weight. This pill is covered by chemically resistant polyether-terketone (PEEK) coating.
When it moves through gastro-intestinal track it starts to detect diseases and abnormalities. A small electronic pill can easily reach areas such as small intestine and large intestine and can deliver real time information to an external system. Total information will be displayed in a monitor. The electronic pill travels to the digestive system, collects data and sends it into the computer with a distance of 1 meter and more. Main parts of electronic pills are four sensors, an ASIC chip, a radio transmitter and a power source.
Electronic Pill Structure
This device consists of 4 microelectronic sensors. First one is Silicon Diode: which is used to identify the body temperature. Silicon diodes are the commonly used temperature sensors in electronic equipments. This temperature sensor is attached in the substrate. The main advantage of this sensor is that, it is a silicon integrated circuit at very low cost. Second one is ISFET (Ion-Sensitive Field-Effect Transistor). ISFET is used for measuring ion concentration in solution. There are so many diseases which occur due to abnormal pH level. They are; reflux of oesophagus, inflammatory bowel disease, hypertension, activity of fermenting bacteria, pancreatic disease, level of acid excretion and effect of GI specific drugs on target organs. Another one is a Direct Contact Gold Electrode. It helps to measure conductivity. Gold has the best conductivity compared to other elements, so it gives accurate value. Conductivity measures are done by measuring the contents of water and salt absorption, breakdown of organic compounds into charged colloids and the bile secretion.
Three-Electrode Electrochemical Cell is the fourth sensor in electronic pill. It is used to calculate rate of dissolved oxygen and identify the activity of aerobic bacteria in small intestine and large intestine. All these sensors are controlled by application specific integrated circuit. Also, all the other components of the electronic pill are connected to ASIC.
ASIC consist of analog signal conditioning, 10bit analog to digital convertor/digital to analog convertor, relaxation oscillator circuit (OSC) and digital signal processing circuit. All these circuits are powered by two SR48 Ag2O batteries. It has 35 hours working capacity and supply voltage is about 3.1 V. Power consumption is 15.5 mW. Sensors are fabricated on two silicon chips that are located at the front end of the capsule. Both pH and oxygen sensors are enclosed by two separate 8 nL electrolyte chambers containing a 0.1 KOH solution retained in a 0.2% calcium alginate gel. Oxygen sensor is covered by 12 µm thick film of teflon and the pH sensor is covered by 12 µm thick film of nafion. Both sensors are protected by a 15 µm thick dialysis membrane of polycarbonate. All the datas are collected by ASIC and are send it into the base station. From this base station doctors identify the problem. Here the radio transmitter transmits all the datas to the receiving end. Size of the radio transmitter is about 8x4x3 mm. Frequency shift Keying is the modulation scheme used in this radio transmitter. Data transfer rate is 1 Kbps. Frequency is about 40.01 KHz at 20o C. 10 KHz is the bandwidth of the signal that was generated by the radio transmitter. It consumes 2.2 mA of current at 6.8 mW power.
Visual based electronic pill consist of a camera. By using this camera entire picture can be captured and it is send through a wireless connection. Earlier, the electronic pills have narrow band transmission and have limited number of camera pixels. The allowable bandwidth in Medical Implant Communication Services (MICS) is only 300 KHz. It is very difficult to transmit high quality videos during real time transmission. In UWB communication (wideband technology), data rate transmission is equal to or higher than 100 Mbps.
After diagnosis, the electronic pill can come out through bowel movement. In medical field other name for electronic pill is “Magical pill for health care”, because it is very easy to detect disease infected areas or any other abnormalities. Power consumption is very low. Size of this pill is very small, so it is very easy to use. The main drawback of electronic pill is, it is very expensive one, and not available in many countries. Can’t detect radiation abnormalities is one of its another disadvantage. Mainly electronic pills are classified into two types; first one include Camera, which collect disease detected areas and send it to the system, and the second one contains only Sensors. These sensors measure pH level, temperature, oxygen level etc.
Recent Research Outcomes on Electronic Pill
||640 X 4S0 pixels
||3 V coin cell
||NA (2 mW for Tx)
||VGA, 0-2 fps
||768 X 494 pixels
||pH and Temperature
||Sensory: pH and Temperature
||2x1.5V SR48 Ag2O
5.6 mW, 5 m
||3-V coin cell (CR1025)
||pH, temperature, oxygen level