Electronic Design

Smart Pill Goes On A Fantastic Voyage

In science fiction, doctors often shrink themselves to enter the human body and investigate mysterious illnesses. But SmartPill Corp. has a much easier solution in mind for the 3 million Americans who have gastrointestinal (GI) problems severe enough to require hospitalization—34% of which have no known causes. The company simply shrank the tools doctors would use for diagnosis.

The system comprises the SmartPill pH.p capsule, a data receiver, a docking station, a SmartPill activation feature, the MotillGI software, and a laptop computer (Fig. 1). It combines capsule manometry and RF telemetry to communicate pH and pressure measurements for accurate, flexible, and simple diagnosis of GI tract disorders.

A key element of the system is a 13- by 26-mm sensorladen ingestible and disposable pill that enables measurements of GI tract pressure, pH, and transit time parameters. It lets GI specialists view GI tract motility and quickly and accurately diagnose disorders like irritable bowel syndrome, inflammatory bowel disease, ulcers, lesions, small bond cancers and polyps, and gastroesophegal reflux disorder.

The patient's body doesn't absorb the pill after it's swallowed. The pill doesn't interact with the GI tract either, except to be propelled via peristalsis when patients empty their bowels. The pill's sensors transmit data to a receiver patients wear on a belt while they go about their daily activities. The data then is downloaded in the doctor's office, via the docking station, to the computer for analysis.

"The SmartPill Monitoring system is the most accurate on the market," says John R. Semler, chief technology officer of SmartPill Corp. "It compares very favorably with current diagnostic methods for measuring gastric emptying time."

Unlike other GI diagnostic systems, this system allows for greater patient mobility, which in turn provides a more natural test environment. Patients can go about their normal daily activities without any restrictions while the pill goes to work.

Standard gastric emptying scintigraphy tests (GESTs) aren't very sensitive. They also can provide poor reproducibility and poor correlation with symptoms. In comparison, the SmartPill Monitoring system features a sensitivity of 0.85 (versus 0.69 for GESTs) at T50. (T50 and T90 are two standard medical imaging tests.)

The pill's microelectromechanical system (MEMS) sensors measure pressure, pH, and temperature. One of these sensors is an insulated-gate FET (IsFET). The pill also contains temperature-compensation circuitry, a 16-bit analogtodigital converter (ADC), a microprocessor, and a transmitter. Power control circuitry is included along with a 1.5-V silver-oxide battery. Data is transmitted from the pill over the industrial, scientific, and medical (ISM) band in a pulsed burst-mode fashion (Fig. 2).

"Getting all of this circuitry into a small capsule was a great achievement," says Dave D'andrea, the pill's inventor and design engineering manager. "Working with Teledyne Microelectronics, which manufactured the pill, we made use of three-layer pc boards and flexible interconnects to get the job done."

SmartPill Corp. is pricing the system at $15,000. This includes the laptop computer, the docking station, an activation fixture, the data receiver, software, and user manuals. Pills cost $500 each. The Windows-based laptop has been optimized for working with the Smart Pill monitoring system.

TAGS: Components
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