For practical utilization of this cell monitoring system, a simple,
reliable, and most importantly, user-friendly optical sensing
device was necessary. Toward this, we developed an optical instrument
employing an everyday information technology (IT) device—a
smartphone. Among the high-performance sensors installed in
smartphones (such as gyroscope, accelerometer, magnetometer,
and proximity and light sensor), embedded charge-couple device
(CCD) cameras, owing to their high resolution and definition, have