Development of an automatic blood sampling system: control of the puncturing needle by measuring forces

For automatic blood sampling to occur, a needle must stop automatically once it is introduced to the blood vessel. Medical technologists can confirm, by the changes in puncturing force, the moment at which the tip of the needle enters the blood vessel. To achieve automatic blood sampling, the authors have attempted to measure the force required to puncture a blood vessel. A device with a force sensor installed inside was developed to measure the force acting on the needle. Experiments involving puncturing of the vena mediana cubiti of 10 volunteers and a rabbit ear vein were performed. A medical technologist was asked to puncture the vena mediana cubiti. In the rabbit experiments, the measuring device was set on an electric-driven linear stage, which was controlled by a personal computer. In the rabbit experiments, a typical peak was observed in the waveform of the puncturing force, and in the volunteer experiments, two typical peaks were observed. It was considered that just after the last peak appeared, the tip of the needle was inserted into the blood vessel. These results have shown that measuring the force at the time of puncturing a blood vessel will be applicable to achieving automatic blood sampling