Method for detecting an error state when aspirating a liquid
Inventors
FARELL, Danny • LAARMANN, Anna Katharina
Assignees
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Publication Number
US-11867579-B2
Publication Date
2024-01-09
Expiration Date
Abstract
A method for detecting an error state when aspirating a liquid to identify whether a pre-determined volume of liquid was aspirated. The method including: immersing a tip of an aspiration needle in the liquid, aspirating a predetermined partial volume of the liquid in the aspiration needle, continuously acquiring a sensor signal curve, which indicates a pressure in the aspiration needle, during an overall time period, detecting the error state in the case that the sensor signal falls below a first threshold value during the predetermined time period, characterized by providing a reference signal curve, determining a deviation measure, which indicates a deviation of the sensor signal curve from the reference signal curve during the further time period, providing a predetermined second threshold value, detecting the error state as a function of the deviation measure and the second threshold value.
Core Innovation
The invention relates to a method for detecting an error state when aspirating a liquid using an aspiration needle immersed in the liquid. A negative pressure is generated in the aspiration needle for a predefined time period to aspirate a predetermined partial volume of the liquid into the aspiration needle. During an overall time period comprising the predetermined time period and a further time period following it, a sensor signal curve is continuously acquired by continuous measurement of a sensor signal indicating a pressure in the aspiration needle.
A reference signal curve is provided. For the further time period, a deviation measure is determined, which indicates a deviation of the sensor signal curve from the reference signal curve. A first threshold value and a predetermined second threshold value are provided so that an error state is detected if the sensor signal falls below the first threshold value during the predetermined time period or, after expiration of the further time period, if the deviation measure deviates sufficiently from the second threshold value.
The disclosed approach targets detection not only during the predetermined time period based on a direct threshold crossing, but also after the further time period by evaluating a curve-deviation measure between the sensor signal curve and the reference signal curve. Additional refinements describe time alignment of the sensor signal curve to the reference signal curve via correlation, generating the reference signal curve from a base reference curve modified depending on a target aspiration volume, including multiple base reference curves with amplitude scaling, and optionally mean value filtering of the sensor signal.
A device architecture is described including an aspiration needle, an activatable movement device, a pressure generating unit, a pressure sensor unit, and an activation and evaluation unit that acquires the sensor signal curve, provides the reference signal curve, determines the deviation measure for the further time period, and outputs an error signal.
Claims Coverage
The document includes two independent claims, a method and a device. Both independent claims share the same inventive core: time-segmented monitoring with continuous acquisition of a sensor signal curve, comparison to a reference signal curve via a deviation measure, and error detection using a first threshold during the predetermined time period and a second threshold based on the deviation measure after the further time period.
Time-segmented error detection during aspiration using continuous sensor signal curve acquisition
Continuously acquiring a sensor signal curve via continuous measurement of a sensor signal indicating a pressure in the aspiration needle during an overall time period comprising a predetermined time period and a further time period following it.
Error detection by first-threshold crossing during the predetermined time period
Detecting an error state if the sensor signal falls below a first threshold value during the predetermined time period.
Reference-curve deviation measure for error detection after the further time period
Providing a reference signal curve, determining a deviation measure indicating a deviation of the sensor signal curve from the reference signal curve for the further time period, and detecting the error state after expiration of the further time period if the deviation measure deviates sufficiently from a predetermined second threshold value.
Device implementing aspiration needle monitoring with pressure generation, sensor measurement, and activation/evaluation interfaces
Providing an aspiration needle, a pressure generating unit, a pressure sensor unit, and an activation and evaluation unit with interfaces to the pressure generating unit, the pressure sensor unit, and the movement device, wherein the activation and evaluation unit is designed to activate the movement device so that the tip is immersed in the liquid and to perform the time-period monitoring, reference provision, deviation measure determination for the further time period, and threshold-based error detection.
Together, the independent claims cover both a method and a corresponding device in which continuous pressure-indicative sensor signal curve acquisition is performed over the predetermined time period and the further time period, and an error state is detected either by the first threshold during the predetermined time period or by a reference-curve deviation measure relative to the reference signal curve exceeding the second threshold after the further time period.
Stated Advantages
Detecting an error state after expiration of the further time period using a deviation measure relative to a reference signal curve.
Enabling error detection based on both direct sensor signal level during the predetermined time period and curve deviation after the further time period.
Detecting partial clogging and total closure scenarios that may not trigger the first threshold during the predetermined time period.
Documented Applications
Not explicitly described in patent.
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