Method and Apparatus for Providing Rechargeable Power in Data Monitoring and Management Systems

Abstract

Method and apparatus for providing a disposable power supply source integrated into the housing of the transmitter unit mount that is placed on the skin of the patient, and configured to receive the transmitter unit is disclosed. The transmitter unit mount is configured to be disposable with the analyte sensor so that power supply providing power to the transmitter unit is also replaced. The transmitter unit may include a rechargeable battery that is recharged by the power supply unit of the transmitter unit mount when the transmitter is mounted to the transmitter unit mount. Other energy store configurations including single large capacitor (supercap) or a capacitor and DC/DC converter configurations are disclosed.

Description

BACKGROUND

Analayte, e.g., glucose, monitoring systems including continuous and discrete monitoring systems generally include a small, lightweight battery powered and microprocessor controlled system which is configured to detect signals proportional to the corresponding measured glucose levels using an electrometer, and RF signals to transmit the collected data. One aspect of certain glucose monitoring systems include a transcutaneous or subcutaneous analyte sensor configuration which is, for example, partially mounted on the skin of a subject whose glucose level is to be monitored. The sensor cell may use a two or three-electrode (work, reference and counter electrodes) configuration driven by a controlled potential (potentiostat) analog circuit connected through a contact system.

The analyte sensor may be configured so that a portion thereof is placed under the skin of the patient so as to detect the analyte levels of the patient, and another portion or segment of the analyte sensor is in communication with the transmitter unit. The transmitter unit is configured to transmit the analyte levels detected by the sensor over a wireless communication link such as an RF (radio frequency) communication link. To transmit signals, the transmitter unit requires a power supply such as a battery. Generally, batteries have a limited life span and require periodic replacement. More specifically, depending on the power consumption of the transmitter unit, the power supply in the transmitter unit may require frequent replacement, or the transmitter unit may require replacement (e.g, disposable power supply such as disposable battery).

This may be cumbersome and inconvenient to the patient. Moreover, in continuous glucose monitoring systems, when the transmitter unit fails to transmit the glucose data from the sensor due to power failure, the patient may be approaching a critical physiological state such as hyperglycemia or hypoglycemia with little warning or knowledge. This could potentially be fatal to the patient.

At the same time, however, it may be undesirable to limit the functions of the transmitter so as to reduce the power consumption in order to prolong the battery life of the transmitter. For example, the transmitter unit may be configured to transmit less periodically or frequently to save battery power—this may in turn potentially result in inaccurate determination of monitored glucose levels as the detected levels are not sufficiently close together to provide a comprehensive result of the continuous monitoring.

Moreover, increasing the battery size may prolong the operating life of the transmitter unit, but would result in a more physically cumbersome design, and would add extra weight to be carried by the patient which is generally undesirable.

In view of the foregoing, it would be desirable to have an approach to provide a rechargeable power supply for the transmitter unit in the data monitoring and management system such that the compact, lightweight configuration of the transmitter unit worn by the patient can be maintained. Moreover, in view of the foregoing, it would be desirable to have various options for the power supply and/or a rechargeable power supply for the transmitter unit in the data monitoring and management systems.

SUMMARY OF THE INVENTION

In view of the foregoing, in accordance with the various embodiments of the present invention, there is provided a method and apparatus for providing a disposable power supply source integrated into the housing of the transmitter unit mount that is placed on the skin of the patient, and configured to receive or “mate” with the transmitter unit. The transmitter unit mount is configured to be disposable with the analyte sensor, such that with each replacement of the analyte sensor (for example, every three or five days), the power supply providing power to the transmitter unit is also replaced.

In a further embodiment of the present invention, the transmitter unit may further be configured to include a rechargeable battery such that when the transmitter unit is mounted to the transmitter unit mount (that includes a separate disposable power supply), the power supply unit of the transmitter unit mount is configured to charge the rechargeable power supply of the transmitter unit. In this manner, the transmitter unit may be configured to maintain the communication link with the corresponding receiver unit during the period when the patient is replacing the analyte sensor (along with the transmitter unit mount).

Yet in a further embodiment of the present invention, the transmitter may be configured to include a series of capacitor combinations (and/or in conjunction with other circuitry including a corresponding series of DC/DC converters) configured to store charge so as to provide power to the transmitter. In one embodiment, the capacitor may include a single large capacitor (supercap) as energy store to provide power to the transmitter in the data monitoring and management system.

These and other objects, features and advantages of the present invention will become more fully apparent from the following detailed description of the embodiments, the appended claims and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a block diagram of a data monitoring and management system for practicing one embodiment of the present invention;

FIG. 2 is a block diagram of the transmitter of the data monitoring and management system shown in FIG. 1 in accordance with one embodiment of the present invention;

FIG. 3 illustrates a cross sectional view of the transmitter and transmitter mount configuration for providing power to the transmitter in the data monitoring and management system in accordance with one embodiment of the present invention;

FIG. 4 is a circuit diagram of the energy storage approach for providing power to the transmitter in the data monitoring and management system in accordance with one embodiment of the present invention; and

FIG. 5 illustrates another energy storage approach for providing power to the transmitter in the data monitoring and management system in accordance with another embodiment of the present invention.

DETAILED DESCRIPTION

FIG. 1 illustrates a data monitoring and management system such as, for example, an analyte (e.g., glucose) monitoring system 100 in accordance with one embodiment of the present invention. The subject invention is further described primarily with respect to a glucose monitoring system for convenience and such description is in no way intended to limit the scope of the invention. It is to be understood that the analyte monitoring system may be configured to monitor a variety of analytes, e.g., lactate, and the like.

Indeed, analytes that may be monitored include, for example, acetyl choline, amylase, bilirubin, cholesterol, chorionic gonadotropin, creatine kinase (e.g., CK-MB), creatine, DNA, fructosamine, glucose, glutamine, growth hormones, hormones, ketones, lactate, peroxide, prostate-specific antigen, prothrombin, RNA, thyroid stimulating hormone, and troponin. The concentration of drugs, such as, for example, antibiotics (e.g., gentamicin, vancomycin, and the like), digitoxin, digoxin, drugs of abuse, theophylline, and warfarin, may also be monitored.

The glucose monitoring system 100 includes a sensor 101, a transmitter 102 coupled to the sensor 101, and a receiver 104 which is configured to communicate with the transmitter 102 via a communication link 103. The receiver 104 may be further configured to transmit data to a data processing terminal 105 for evaluating the data received by the receiver 104. Moreover, the data processing terminal in one embodiment may be configured to receive data directly from the transmitter 102 via a communication link 106 which may optionally be configured for bi-directional communication.

Only one sensor 101, transmitter 102, communication link 103, receiver 104, and data processing terminal 105 are shown in the embodiment of the glucose monitoring system 100 illustrated in FIG. 1. However, it will be appreciated by one of ordinary skill in the art that the glucose monitoring system 100 may include one or more sensor 101, transmitter 102, communication link 103, receiver 104, and data processing terminal 105, where each receiver 104 is uniquely synchronized with a respective transmitter 102. Moreover, within the scope of the present invention, the glucose monitoring system 100 may be a continuous monitoring system, or semi-continuous, or a discrete monitoring system.

In one embodiment of the present invention, the sensor 101 is physically positioned in or on the body of a user whose glucose level is being monitored. The sensor 101 may be configured to continuously sample the glucose level of the user and convert the sampled glucose level into a corresponding data signal for transmission by the transmitter 102. In one embodiment, the transmitter 102 is mounted on the sensor 101 so that both devices are positioned on the user's body. The transmitter 102 performs data processing such as filtering and encoding on data signals, each of which corresponds to a sampled glucose level of the user, for transmission to the receiver 104 via the communication link 103.

In one embodiment, the glucose monitoring system 100 is configured as a one-way RF communication path from the transmitter 102 to the receiver 104. In such embodiment, the transmitter 102 transmits the sampled data signals received from the sensor 101 without acknowledgement from the receiver 104 that the transmitted sampled data signals have been received. For example, the transmitter 102 may be configured to transmit the encoded sampled data signals at a fixed rate (e.g., at one minute intervals) after the completion of the initial power on procedure. Likewise, the receiver 104 may be configured to detect such transmitted encoded sampled data signals at predetermined time intervals. Alternatively, the glucose monitoring system 100 may be configured with a bi-directional RF (or otherwise) communication between the transmitter 102 and the receiver 104.

Additionally, in one aspect, the receiver 104 may include two sections. The first section is an analog interface section that is configured to communicate with the transmitter 102 via the communication link 103. In one embodiment, the analog interface section may include an RF receiver and an antenna for receiving and amplifying the data signals from the transmitter 102, which are thereafter, demodulated with a local oscillator and filtered through a band-pass filter. The second section of the receiver 104 is a data processing section which is configured to process the data signals received from the transmitter 102 such as by performing data decoding, error detection and correction, data clock generation, and data bit recovery.

In operation, upon completing the power-on procedure, the receiver 104 is configured to detect the presence of the transmitter 102 within its range based on, for example, the strength of the detected data signals received from the transmitter 102 or a predetermined transmitter identification information. Upon successful synchronization with the corresponding transmitter 102, the receiver 104 is configured to begin receiving from the transmitter 102 data signals corresponding to the user's detected glucose level. More specifically, the receiver 104 in one embodiment is configured to perform synchronized time hopping with the corresponding synchronized transmitter 102 via the communication link 103 to obtain the user's detected glucose level.

Referring again to FIG. 1, the data processing terminal 105 may include a personal computer, a portable computer such as a laptop or a handheld device (e.g., personal digital assistants (PDAs)), and the like, each of which may be configured for data communication with the receiver via a wired or a wireless connection. Additionally, the data processing terminal 105 may further be connected to a data network (not shown) for storing, retrieving and updating data corresponding to the detected glucose level of the user.

Within the scope of the present invention, the data processing terminal 105 may include an infusion device such as an insulin infusion pump or the like, which may be configured to administer insulin to patients, and which may be configured to communicate with the receiver unit 104 for receiving, among others, the measured glucose level. Alternatively, the receiver unit 104 may be configured to integrate an infusion device therein so that the receiver unit 104 is configured to administer insulin therapy to patients, for example, for administering and modifying basal profiles, as well as for determining appropriate boluses for administration based on, among others, the detected glucose levels received from the transmitter 102.

Additionally, the transmitter 102, the receiver 104 and the data processing terminal 105 may each be configured for bi-directional wireless communication such that each of the transmitter 102, the receiver 104 and the data processing terminal 105 may be configured to communicate (that is, transmit data to and receive data from) with each other via the wireless communication link 103. More specifically, the data processing terminal 105 may in one embodiment be configured to receive data directly from the transmitter 102 via the communication link 106, where the communication link 106, as described above, may be configured for bi-directional communication. In this embodiment, the data processing terminal 105 which may include an insulin pump, may be configured to receive the glucose signals from the transmitter 102, and thus, incorporate the functions of the receiver 104 including data processing for managing the patient's insulin therapy and glucose monitoring. In one embodiment, the communication link 103 may include one or more of an RF communication protocol, an infrared communication protocol, a Bluetooth enabled communication protocol, an 802.11x wireless communication protocol, or an equivalent wireless communication protocol which would allow secure, wireless communication of several units (for example, per HIPPA requirements) while avoiding potential data collision and interference.

FIG. 2 is a block diagram of the transmitter of the data monitoring and detection system shown in FIG. 1 in accordance with one embodiment of the present invention. Referring to the Figure, the transmitter 102 in one embodiment includes an analog interface 201 configured to communicate with the sensor 101 (FIG. 1), a user input 202, and a temperature measurement section 203, each of which is operatively coupled to a transmitter processor 204 such as a central processing unit (CPU). As can be seen from FIG. 2, there are provided four contacts, three of which are electrodes—work electrode (W) 210, guard contact (G) 211, reference electrode (R) 212, and counter electrode (C) 213, each operatively coupled to the analog interface 201 of the transmitter 102 for connection to the sensor unit 101 (FIG. 1). In one embodiment, each of the work electrode (W) 210, guard contact (G) 211, reference electrode (R) 212, and counter electrode (C) 213 may be made using a conductive material that is either printed or etched, for example, such as carbon which may be printed, or metal foil (e.g., gold) which may be etched.

Further shown in FIG. 2 are a transmitter serial communication section 205 and an RF transmitter 206, each of which is also operatively coupled to the transmitter processor 204. Moreover, a power supply 207 such as a battery is also provided in the transmitter 102 to provide the necessary power for the transmitter 102. Additionally, as can be seen from the Figure, clock 208 is provided to, among others, supply real time information to the transmitter processor 204.

In one embodiment, a unidirectional input path is established from the sensor 101 (FIG. 1) and/or manufacturing and testing equipment to the analog interface 201 of the transmitter 102, while a unidirectional output is established from the output of the RF transmitter 206 of the transmitter 102 for transmission to the receiver 104. In this manner, a data path is shown in FIG. 2 between the aforementioned unidirectional input and output via a dedicated link 209 from the analog interface 201 to serial communication section 205, thereafter to the processor 204, and then to the RF transmitter 206. As such, in one embodiment, via the data path described above, the transmitter 102 is configured to transmit to the receiver 104 (FIG. 1), via the communication link 103 (FIG. 1), processed and encoded data signals received from the sensor 101 (FIG. 1). Additionally, the unidirectional communication data path between the analog interface 201 and the RF transmitter 206 discussed above allows for the configuration of the transmitter 102 for operation upon completion of the manufacturing process as well as for direct communication for diagnostic and testing purposes.

As discussed above, the transmitter processor 204 is configured to transmit control signals to the various sections of the transmitter 102 during the operation of the transmitter 102. In one embodiment, the transmitter processor 204 also includes a memory (not shown) for storing data such as the identification information for the transmitter 102, as well as the data signals received from the sensor 101. The stored information may be retrieved and processed for transmission to the receiver 104 under the control of the transmitter processor 204. Furthermore, the power supply 207 may include a commercially available battery.

The transmitter 102 is also configured such that the power supply section 207 is capable of providing power to the transmitter for a minimum of about three months of continuous operation after having been stored for about eighteen months in a low-power (non-operating) mode. In one embodiment, this may be achieved by the transmitter processor 204 operating in low power modes in the non-operating state, for example, drawing no more than approximately 1 μA of current. Indeed, in one embodiment, the final step during the manufacturing process of the transmitter 102 may place the transmitter 102 in the lower power, non-operating state (i.e., post-manufacture sleep mode). In this manner, the shelf life of the transmitter 102 may be significantly improved. Moreover, as shown in FIG. 2, while the power supply unit 207 is shown as coupled to the processor 204, and as such, the processor 204 is configured to provide control of the power supply unit 207, it should be noted that within the scope of the present invention, the power supply unit 207 is configured to provide the necessary power to each of the components of the transmitter unit 102 shown in FIG. 2.

Referring back to FIG. 2, the power supply section 207 of the transmitter 102 in one embodiment may include a rechargeable battery unit that may be recharged by a separate power supply recharging unit so that the transmitter 102 may be powered for a longer period of usage time. Moreover, in one embodiment, the transmitter 102 may be configured without a battery in the power supply section 207, in which case the transmitter 102 may be configured to receive power from an external power supply source (for example, a battery) as discussed in further detail below.

Referring yet again to FIG. 2, the temperature measurement section 203 of the transmitter 102 is configured to monitor the temperature of the skin near the sensor insertion site. The temperature reading is used to adjust the glucose readings obtained from the analog interface 201. The RF transmitter 206 of the transmitter 102 may be configured for operation in the frequency band of 315 MHz to 322 MHz, for example, in the United States. Further, in one embodiment, the RF transmitter 206 is configured to modulate the carrier frequency by performing Frequency Shift Keying and Manchester encoding. In one embodiment, the data transmission rate is 19,200 symbols per second, with a minimum transmission range for communication with the receiver 104.

Referring yet again to FIG. 2, also shown is a leak detection circuit 214 coupled to the guard electrode (G) 211 and the processor 204 in the transmitter 102 (FIG. 1) of the data monitoring and management system 100. The leak detection circuit 214 in accordance with one embodiment of the present invention may be configured to detect leakage current in the sensor 101 to determine whether the measured sensor data are corrupt or whether the measured data from the sensor 101 is accurate.

Additional detailed description of the continuous glucose monitoring system, its various components including the functional descriptions of the transmitter are provided in U.S. Pat. No. 6,175,752 issued Jan. 16, 2001 entitled “Analyte Monitoring Device and Methods of Use”, and in application Ser. No. 10/745,878 filed Dec. 26, 2003 entitled “Continuous Glucose Monitoring System and Methods of Use”, each assigned to the Assignee of the present application, and the disclosures of each of which are incorporated herein by reference for all purposes.

FIG. 3 illustrates a cross sectional view of the transmitter and transmitter mount configuration for providing power to the transmitter in the data monitoring and management system in accordance with one embodiment of the present invention. Referring to the Figure, there is shown a transmitter unit mount 302 which is placed on the skin 301 of the patient, and configured to receive a portion of the sensor 101, and the other end portion of the sensor is inserted, e.g., subcutaneously, under the patient's skin 301. Referring to FIG. 3, the transmitter unit mount 302 is configured to receive or “mate” with the transmitter 102 so that the transmitter 102 is in electrical contact with the sensor 101 that extends from the patient's skin 301 at the sensor contact 304. In one embodiment and as discussed above, the sensor contact 304 may be configured to operatively couple the analog interface unit 201 of the transmitter 102 with the sensor electrodes and contacts (working electrode 210, guard trace 211, reference electrode 212, and counter electrode 213).

While not shown in the Figure, the transmitter unit mount 302 in one embodiment is firmly affixable onto the patient's skin 301 by an adhesive layer on the surface of the transmitter unit mount 302 that is in contact with the patient's skin 301. In this manner, the patient's movement of the body does not substantially affect the position of the transmitter unit mount 302, and thus the sensor 101 in contact with the transmitter 102. Referring back to FIG. 3, also shown is a power supply 303 (such as, for example, a battery) mounted to the transmitter unit mount 302. In one embodiment, the power supply 303 is positioned to establish electrical contact with the transmitter 102 at the power supply contact 305, when the transmitter is mounted onto the transmitter unit mount 302.

More specifically, in this configuration, the internal power supply 207 (FIG. 2) and/or other components of the transmitter 102 are coupled to the external power supply 303 via the power supply contact 305. In this manner, when the transmitter 102 is mounted to the transmitter unit mount 302, the internal power supply 207 of the transmitter 102 is configured to receive power from the external power supply 303, and thus may be configured to transmit sensor data received from the sensor 101.

Within the scope of the present invention, the external power supply 303 mounted to the transmitter unit mount 302 may include a disposable battery, or a printed battery which may be printed onto the surface of the transmitter unit mount 302 on the surface where the transmitter 102 is configured to physically contact the transmitter unit mount 302.

In a further embodiment, as discussed above, the internal power supply 207 of the transmitter 102 may include a rechargeable battery which may be configured to receive power to recharge from the external power supply 303 mounted to the transmitter unit mount 302, when the transmitter 102 is mounted to the transmitter unit mount 302. In this manner, the external power supply 303 may be configured to provide power to recharge the internal power supply 207 of the transmitter 102, and further, to provide power to the transmitter 102.

Within the scope of the present invention, the rechargeable internal power supply 207 in the transmitter 102 and the external power supply 303 mounted on the transmitter unit mount 302 may include one or more of alkaline, nickel metal hydride, lithium, nickel cadmium, lithium hydride, polymer batteries, polymorphic heavy ion salts, bi-metallic interstitial lattice ionic crystals or ferromagnetic materials. Furthermore, in one embodiment, the external power supply 303 may be mounted or coupled to the transmitter unit mount 302 by one of insert molding, welding, casting or printing.

In the manner described above, in accordance with one embodiment of the present invention, a transmitter unit mount 302 may be configured to integrate a power supply 303, such as a battery, that is disposable, so that when the transmitter 102 is mounted, power is provided to the transmitter 102. When the transmitter 102 is dismounted from the transmitter unit mount 302, then the transmitter 102 may be powered off and the transmitter unit mount 302 and the power supply 303 are discarded. The transmitter 102 in one embodiment may also be configured to enter a low power sleep state powered by the remaining charge in the power supply 207.

In one embodiment, the power supply 303 which includes disposable batteries can be very small since it is a disposable battery which is to be replaced with each sensor 101 replacement, and thus does not require a large capacity (thus allowing the size of the battery to be small). One example of such disposable battery as power supply 303 is a silver oxide battery.

Within the scope of the present invention, there is also provided an embodiment which includes a second rechargeable battery integrated with the transmitter 102 so that the transmitter 102 may be configured to maintain the RF communication link with the receiver 104 and/or the data processing terminal 105. In this embodiment, as discussed above, when the transmitter 102 is mounted to the transmitter mount unit 302, the internal power supply 207 of the transmitter 102 is configured to recharge from the energy powered by the external power supply 303 of the transmitter unit mount 302.

FIG. 4 is a circuit diagram of the energy storage approach for providing power to the transmitter in the data monitoring and management system in accordance with one embodiment of the present invention. Referring to the Figure, there is shown the disposable power supply 401 of the transmitter unit mount 302 which is configured to be replaced with the replacement of the sensor 101 (FIG. 1). Also, shown is the transmitter 102 including, among others, the internal power supply 207, which, in one embodiment, includes a plurality of DC/DC converters 403, 404, 405, each operatively coupled to a respective capacitors 406, 407, 408. Also shown in FIG. 4 is a resistor 409 operatively coupled to a rechargeable battery 402 of the transmitter 102. The rechargeable battery 402 of the transmitter 102 shown in FIG. 4 in one embodiment corresponds to the power supply 207 of the transmitter 102 shown in FIG. 2.

In one embodiment, referring to FIG. 4, when the transmitter 102 is mounted to the transmitter unit mount 302, the power supply 401 of the transmitter unit mount 302 is configured to charge the rechargeable battery 402 of the transmitter 102. The DC/DC converter 403 in one embodiment is configured to boost the voltage signal from power supply 401 (e.g., 1.5 Volts) to the voltage level needed for the processor 204 of the transmitter 102 to operate (for example, to 3 Volts). Indeed, as shown in FIG. 4, the voltage level at the Analog Front End (AFE) of the transmitter 102 can be derived from the node 410 shown in the Figure.

Referring back to FIG. 4, in one embodiment, the energy from capacitor 406 and/or from the rechargeable battery 402 of the transmitter 102 may be used to charge the capacitor 407 to a predetermined value (e.g., between a 5 Volt to 35 Volt range) by the DC/DC converter 404 boosting the voltage level to the predetermined range from the 3 Volts at node 410. In one embodiment, both the rechargeable battery 402 and the capacitor 406, or alternatively, the rechargeable battery 402 or the capacitor 406, may be used to charge the capacitor 407, depending upon the various system requirements and the design trade-offs. One example of the capacitor 407 is a Tantalum type capacitor.

Indeed, increasing the voltage from 3 Volts to 30 Volts, for example, provides approximately 100 times the energy storage (since the energy stored in a capacitor is equal to one half of the product of the capacitance multiplied with the capacitor voltage squared—i.e., ½CV²). Then, referring again to FIG. 4, the stored energy in capacitor 407 is converted by the DC/DC converter 405 and filtered by capacitor 408 to a functional voltage level which the processor 204 of the transmitter 102 may be configured to utilize for the RF transmission operation (e.g., 3.3 Volts or 5 Volts).

As pulsed (or peak) current is drawn by the processor 204 in the transmitter 102, during the RF transmission operations, the voltage across the capacitor 407 drops from a high value towards the minimum value for DC/DC converter operation. In other words, in one embodiment, the capacitor 407 is “trickle charged” at a low current during periods when the pulse current is not active, and when the large peak load occurs, the capacitor 407 is configured to draw charge from the capacitor and not the source.

In this manner, in one embodiment of the present invention, the DC/DC converters 404 and 405 and the corresponding capacitors 407 and 408, are configured to draw a small current from the energy store (e.g., capacitor 406 or the rechargeable battery 402), and to store energy on capacitor 407 that provides a large peak (pulsed) current capability to the processor 204 and RF transmitter 206. This allows low current drive power sources, such as a printed battery or a low current coin-cell battery to power the transmitter 102 in normal operations. For test and configuration purposes, a more robust power source such as a bench power supply may be used to support continuous operation.

FIG. 5 illustrates another energy storage approach for providing power to the transmitter in the data monitoring and management system in accordance with another embodiment of the present invention. Referring to the Figure, in one embodiment of the present invention, a single large capacitor (supercap) 501 is used for energy store in the transmitter 102, as opposed to, for example, the capacitor 406 shown in the embodiment in FIG. 4. Moreover, it can be seen that the power supply 502 (e.g., battery) of the transmitter 102 shown in FIG. 5 is similar to the power supply 402 shown in FIG. 4. Further, the boost circuit 503 shown in FIG. 5 in one embodiment corresponds to the DC/DC converter 403 of the embodiment shown in FIG. 4.

Referring back to FIG. 5, the use of the single supercap 501 in parallel with the power supply 502 for energy storage has advantages in terms of size and cost. Moreover, it should be noted that the equivalent series resistance (ESR) of the capacitor is an important design consideration. Indeed, in general, supercaps have a higher ESR which tends to limit the efficiency and effectiveness of the supercap design, especially in cases where the working voltage is greater than 2.5 volts. Moreover, within the scope of the present invention, the battery 502 may need to have relatively high current capacity (for example, compared to the rechargeable battery 402 shown in FIG. 4), due to ESR of the supercap 501.

In one embodiment, the supercap 501 may be configured to provide a low internal resistance energy source that allows a large current to be delivered to the transmitter unit 102. It is difficult to achieve this directly from a battery. Small batteries generally cannot deliver a high current, so for a relatively small and compact size design such as for the design of the transmitter unit 102, this provides a significant advantage. Also, while at low temperatures the internal resistance of batteries increase, this may be mitigated by using a supercap or other type of storage capacitor connected in parallel with the battery.

In the manner described above, an apparatus including a data transmission unit in one embodiment includes a sensor, a transmitter base including a first power supply, and a transmitter unit coupled to the transmitter base, the transmitter unit including a second power supply, the transmitter unit further configured to establish electrical contact with the sensor, and further, where the transmitter unit is configured to draw power from one or more of the first power supply and the second power supply.

The sensor may in one embodiment include an analyte sensor transcutaneously positioned in a patient such that at least a portion of the analyte sensor is in fluid contact with a biological fluid of the patient.

Moreover, the first power supply may include a disposable battery, such as, for example, a silver oxide battery, and where the second power supply may include a rechargeable battery configured to selectively draw power from the first power supply.

In a further embodiment, each of the first power supply and the second power supply may include one of a disposable battery or a rechargeable battery.

The transmitter unit in one embodiment may be configured to transmit one or more signals, where the one or more signals correspond to a respective one or more signals received from the sensor, and where the transmitter unit may be configured for wireless communication or may include a physical connection. Additionally, the one or more signal received from the sensor corresponds to one or more analyte levels (for example, glucose levels) of a patient detected by the sensor.

An apparatus in a further embodiment of the present invention includes a sensor transcutaneously positioned in a patient, a transmitter base including a transmitter base power supply, a transmitter unit coupled to the transmitter base power supply of the transmitter base, the transmitter base power supply of the transmitter base configured to provide power to the transmitter unit, the transmitter unit further configured to establish electrical contact with the sensor.

In one embodiment, the sensor may include an analyte sensor where least a portion of the analyte sensor is in fluid contact with a biological fluid of the patient, where the biological fluid includes one of interstitial fluid, lactate or oxygen.

Moreover, the apparatus in one embodiment may also include a receiver unit configured to receive the one or more signals from the transmitter unit.

In still a further embodiment, the transmitter base power supply may include a disposable battery such as for example, a silver oxide battery.

Also, the transmitter unit may further include a transmitter unit power supply disposed substantially within the housing of the transmitter unit, where the transmitter unit power supply may in one embodiment include a rechargeable battery, and also, where the rechargeable battery may be configured to substantially draw power from the transmitter base power supply.

An apparatus in still a further embodiment includes a rechargeable battery, and a transmitter unit coupled to the rechargeable battery configured to draw power from the rechargeable battery.

A method in still another embodiment of the present invention includes the steps of providing a power supply to a transmitter mount, operatively coupling a transmitter unit to the transmitter mount such that the transmitter unit is in electrical contact with the power supply, operatively coupling a transcutaneously positioned analyte sensor to the transmitter unit such that the transmitter unit receives one or more signals corresponding to one or more analyte levels from the sensor.

Various other modifications and alterations in the structure and method of operation of this invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. It is intended that the following claims define the scope of the present invention and that structures and methods within the scope of these claims and their equivalents be covered thereby.

Claims

1. An apparatus comprising: a transmitter including an analog front end, a processor, a first power supply configured to provide an operational voltage level to the analog front end, and a single large capacitor, wherein the first power supply is coupled to a boost circuit, and wherein the single large capacitor is coupled in parallel with the first power supply; anda transmitter mount configured to receive the transmitter and including a second power supply configured to provide a supply voltage level to the first power supply of the transmitter to charge the first power supply of the transmitter when the transmitter is received by the transmitter mount;wherein the boost circuit is configured to convert the supply voltage level received from the second power supply to the operational voltage level and wherein the single large capacitor is configured to store the operational voltage.

2. The apparatus of claim 1 wherein the second power supply has a high current capacity relative to that of the first power supply.

3. The apparatus of claim 1 further comprising a replaceable sensor configured to electrically couple with the analog front end of the transmitter.

4. The apparatus of claim 3 wherein the second power supply of the transmitter mount is configured to be replaced upon replacement of the sensor.

5. The apparatus of claim 3 wherein the sensor includes a transcutaneous insertion portion adapted for transcutaneous positioning under a skin surface of a patient.

6. The apparatus of claim 5 wherein the sensor is an analyte sensor configured to generate multiple analyte-related signals and wherein the transmitter is configured to transmit one or more signals corresponding to a respective one or more of the multiple analyte-related signals.

7. The apparatus of claim 1 wherein the first power supply is a rechargeable battery.

8. The apparatus of claim 1 wherein the second power supply is a replaceable battery.

9. The apparatus of claim 1 wherein the first power supply is a rechargeable battery, and further, wherein the second power supply is a replaceable battery.

10. An apparatus comprising: a transmitter including an analog front end, a processor and an internal power supply configured to provide a first operational voltage level to the analog front end, the internal power supply including a rechargeable battery coupled to a power circuit including a first DC/DC converter operatively coupled to a first capacitor, a second DC/DC converter operatively coupled to a second capacitor, and a third DC/DC converter operatively coupled to a third capacitor; anda transmitter mount configured to receive the transmitter and including a replaceable power supply configured to provide a supply voltage level to the internal power supply of the transmitter to charge the rechargeable battery of the transmitter when the transmitter is received by the transmitter mount;wherein the first DC/DC converter is configured to convert the supply voltage level received from the replaceable power supply to the first operational voltage level and wherein the first capacitor is configured to store the first operational voltage;wherein the second DC/DC converter is configured to convert the first operational voltage to a predetermined voltage level and wherein the second capacitor is configured to store the predetermined voltage level; andwherein the third DC/DC converter is configured to convert the predetermined voltage level to a second operational voltage level that is provided to the processor when the processor is performing an RF transmission.

11. The apparatus of claim 10 wherein the second operation voltage level and the first operational voltage level are different.

12. The apparatus of claim 10 wherein the second DC/DC converter uses voltage stored in at least one of the first capacitor and the rechargeable battery to convert the first operational voltage to the predetermined voltage level.

13. The apparatus of claim 10 wherein the first operational voltage level is greater than the supply voltage level.

14. The apparatus of claim 13 wherein the first operational voltage level is about twice as great as the supply voltage level.

15. The apparatus of claim 10 wherein the predetermined voltage level is greater than the first operational voltage level.

16. The apparatus of claim 15 wherein the predetermined voltage level is about 10 times as great as the first operational voltage level.

17. The apparatus of claim 10 wherein the second operational voltage level is less than the predetermined voltage level.

18. The apparatus of claim 10 further comprising a replaceable sensor configured to electrically couple with the analog front end of the transmitter.

19. The apparatus of claim 18 wherein the replaceable power supply of the transmitter mount is configured to be replaced upon replacement of the sensor.

20. The apparatus of claim 18 wherein the sensor includes a transcutaneous insertion portion adapted for transcutaneous positioning under a skin surface of a patient.

21. The apparatus of claim 20 wherein the sensor is an analyte sensor configured to generate multiple analyte-related signals and wherein the transmitter is configured to transmit one or more signals corresponding to a respective one or more of the multiple analyte-related signals.