Analyte meter digital sample detection
An analyte meter is configured to digitally test for the presence of a test strip in the meter and for the presence of a sample in the test strip prior to activating an analog current measurement circuit of the meter. A test strip port connector having a plurality of contacts receives an inserted test strip in which the contacts electrically connect to electrodes on the test strip for digitally detecting both the presence of a test strip and a sample added to the test strip. A control circuit monitoring the contacts maintains the analyte meter in a low power mode until detecting both the test strip and the sample, whereupon the control circuit activates the meter and enables an analog analyte measurement circuit.
1. An analyte meter comprising:
an strip port opening configured for receiving a test strip, the strip port opening extending to a strip port connector configured to electrically connect to electrodes disposed on the test strip when the test strip is inserted into the strip port opening, said strip port connector comprising:
a first contact for detecting a digital strip-detect signal when the test strip is inserted into the strip port opening; and
a second contact for detecting a digital sample-detect signal when a sample is applied to the inserted test strip; and
a control circuit electrically connected to the first and second contacts, the control circuit being configured to maintain the analyte meter in a low power mode in the absence of detecting both the digital strip-detect signal and the digital sample-detect signal.
2. The analyte meter of claim 1 , wherein the second contact is coupled to an electronic switch for electrically connecting the second contact to a sample-detect input of the control circuit when the analyte meter is in the low power mode, the electronic switch being controllable by the control circuit.
3. The analyte meter of claim 2 , wherein the second contact is coupled to the electronic switch for electrically connecting the second contact to a an analyte current measurement circuit when the control circuit detects both the digital strip-detect signal and the digital sample-detect signal, and wherein the control circuit switches the analyte meter to an active mode.
4. The analyte meter of claim 1 , wherein the digital strip-detect signal and the digital sample-detect signal each comprise a falling voltage generated by connecting each of the first and second contacts to a different pull-up resistor.
5. The analyte meter of claim 4 , wherein said strip port connector further comprise a ground contact, and wherein the digital strip-detect signal and the digital sample-detect signal each comprise a falling voltage generated by connecting each of the first and second contacts to the ground contact.
6. The analyte meter of claim 5 , wherein said electrodes disposed on the test strip comprise a pair of electrodes configured to be electrically connected only by the sample that is applied to the inserted test strip.
7. The analyte meter of claim 6 , wherein one of said pair of electrodes disposed on the test strip is coupled to the ground contact and the other of said electrodes is coupled to the second contact when the test strip is inserted into the strip port opening.
8. A method of operating an analyte meter having a strip port opening configured for receiving a test strip inserted therein, the method comprising:
maintaining the analyte meter in a low power inactive mode in the absence of a test strip being inserted in the strip port opening;
detecting a digital strip-detect signal at a first interrupt contact of the analyte meter indicating that a test strip is inserted into the strip port opening;
monitoring a second interrupt contact of the analyte meter to detect a digital sample-detect signal indicating that a blood sample is applied to the inserted test strip; and
placing the analyte meter in an active mode, thereby activating an analyte current measuring circuit in the analyte meter in response to detecting the sample-detect signal.
9. The method of claim 8 , wherein said detecting the digital strip-detect signal at the first interrupt contact comprises detecting a voltage drop at the first interrupt contact, the voltage drop at the first interrupt contact being caused by the test strip electrically connecting the first interrupt contact to a ground contact when the test strip is inserted in the strip port opening.
10. The method of claim 9 , wherein said detecting the digital sample-detect signal at the second interrupt contact comprises detecting a voltage drop at the second interrupt contact, the voltage drop at the second interrupt contact being caused by the applied sample electrically connecting the second interrupt contact to the ground contact when the sample is applied to the inserted test strip.
11. The method of claim 10 , wherein said monitoring the second interrupt contact of the analyte meter to detect the digital sample-detect signal includes resuming the low power inactive mode if the digital sample detect signal is not detected by the analyte meter within a preset time limit.
12. The method of claim 11 , wherein said step of activating the analyte current measuring circuit comprises shifting an electrical connection from between the second interrupt contact and an interrupt detection circuit to between the second interrupt contact and an input to the analyte measuring circuit.
13. A digital circuit connected to a strip port opening for generating digital signals indicating both the presence of a test strip in the strip port opening and the presence of a blood sample in the test strip, the digital circuit comprising:
a first contact electrically connected to a first pull up resistor and to a strip detect input of a control circuit;
a second contact electrically connected to a second pull up resistor and to a sample detect input of the control circuit; and
a third contact electrically connected to a ground, wherein the test strip is configured to electrically connect the first contact to the third contact when the test strip is inserted into the strip port opening and to electrically connect the second contact to the third contact when the blood sample is applied to the test strip.
14. The digital circuit of claim 13 , wherein the electrical connection between the first contact and the third contact generates a falling voltage signal received at the strip detect input of the control circuit and the electrical connection between the second contact and the third contact generates a falling voltage signal received at the sample detect input of the control circuit.
15. The digital circuit of claim 14 , wherein the test strip comprises a first electrode for connecting to the second contact when the test strip is inserted into the strip port opening and a second electrode for connecting to the third contact when the test strip is inserted into the strip port opening, and wherein a blood sample applied to the test strip electrically connects the first electrode and the second electrode.
16. The digital circuit of claim 15 , further comprising an electronic switch for disconnecting the second contact from the sample detect input of the control circuit, and for connecting the second contact to a sample current measurement circuit.