Method and apparatus for body fluid sampling and analyte sensing
View Patent ↗A method of controlling a penetrating member is provided. The method comprises providing a lancing device comprising a penetrating member driver having a position sensor and a processor that can determine the relative position and velocity of the penetrating member based on measuring relative position of the penetrating member with respect to time; providing a predetermined velocity control trajectory based on a model of the driver and a model of tissue to be contacted. In some embodiments, a feedforward control to maintain penetrating member velocity along said trajectory.
1. A method of controlling penetrating member velocity, the method comprising:
advancing the penetrating member to reach a first desired velocity;
providing a controller for applying braking force;
applying variable amounts of braking force and driving force to follow a predicted velocity profile, checking in each braking cycle whether braking force should be varied wherein a braking cycle is varied for penetration depth control.
2. The method of claim 1 , further comprising:
controlling penetrating member depth by using an electronic lancet drive system where penetration of the penetrating member in a direction towards to the skin is determined by the amount of force applied by the motor to achieve a certain velocity at impact with the skin.
3. A method of body fluid sampling comprising:
moving a penetrating member at velocities conforming to a selectable velocity profile or motion waveform;
measuring force applied by user to a front end of a lancing device;
determining amount of tissue tenting;
recording tenting and force; and
applying a braking cycle in response to tenting.
4. The method of claim 3 further comprising using force and tenting to determine stratum corneum thickness based on a slope of multiple force and tenting data points.
5. A method of determining contact between a tip of a penetrating member and target tissue of a patient comprising:
(a) Providing a lancing device comprising a penetrating member driver having a position sensor and a processor that can determine the relative position and velocity of the penetrating member based on measuring relative position of the penetrating member with respect to time;
(b) Measuring a magnitude of deceleration of the penetrating member during at least a portion of an inward cutting stroke of a lancing cycle and comparing the magnitude of the measured deceleration to a known value of deceleration; and
(c) Determining contact if the magnitude of the measured deceleration is greater than the magnitude of the known value of deceleration.