Patent Publication Number: US-2012044341-A1

Title: Optofluidic microscope system-on-chip

Description:
This application claims the benefit of provisional patent application No. 61/375,227, filed Aug. 19, 2010, which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     This relates generally to electronic devices and more particularly to electronic devices having optofluidic microscopes. 
     Optofluidic microscopes have been developed that can be used to generate images of cells and other biological specimens. The cells are suspended in a fluid. The fluid flows over a set of image sensor pixels in a channel. The image sensor pixels may be associated with an image sensor pixel array that is masked using a metal layer with a pattern of small holes. In a typical arrangement, the holes and corresponding image sensor pixels are arranged in a diagonal line that crosses the channel. As cells flow through the channel, image data from the pixels may be acquired and processed to form high-resolution images of the cells. 
     In a conventional electronic device containing an optofluidic microscope, operation of microscope components is controlled using external circuitry. Controlling optofluidic microscopes with external circuitry may increase the volume required in an electronic device housing containing an optofluidic microscope and external circuitry and may increase the cost of production of the device. 
     It would be therefore be desirable to provide optofluidic microscopes or other electronic devices with improved control systems. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of an illustrative electronic device having an optofluidic microscope system-on-chip in accordance with an embodiment of the present invention. 
         FIG. 2  is a diagram of an illustrative optofluidic microscope system-on-chip in accordance with an embodiment of the present invention. 
         FIG. 3  is a diagram of an illustrative optofluidic microscope component of an optofluidic microscope system-on-chip in accordance with an embodiment of the present invention. 
         FIG. 4  is a top view of an illustrative fluid channel that contains a gate structure for controlling the flow of fluid in accordance with an embodiment of the present invention. 
         FIG. 5  is a cross-sectional side view of a portion of an image sensor pixel array of the type that may be used in a fluid channel in an electronic device of the type shown in  FIG. 1  in accordance with an embodiment of the present invention. 
         FIG. 6  is a cross-sectional diagram showing how image sensor pixels may be used to form a light sensor associated with a chamber in accordance with an embodiment of the present invention. 
         FIG. 7  is a cross-sectional end view of an illustrative chamber having an entrance port for receiving a sample in accordance with an embodiment of the present invention. 
         FIG. 8  is a cross-sectional end view of an illustrative chamber having a heater and a flow control electrode in accordance with an embodiment of the present invention. 
         FIG. 9  is a cross-sectional end view of an illustrative chamber having a light source and a reactant in accordance with an embodiment of the present invention. 
         FIG. 10  is a top view of an illustrative system having multiple channels with multiple imagers in accordance with an embodiment of the present invention. 
         FIG. 11  is a graph of illustrative control signals that may be applied to the gate structures in respective channels to ensure that a sample is exposed to different reactants for appropriate amounts of time before being imaged by respective imagers in accordance with an embodiment of the present invention. 
         FIG. 12  is a perspective view of illustrative system environment in which an electronic device of the type shown in  FIG. 1  may be used to gather image data of cells and other biological specimens in accordance with an embodiment of the present invention. 
         FIG. 13  is a flow chart of illustrative steps involved in using an electronic device having an optofluidic microscope system-on-chip in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic device of the type that may be used to image and otherwise evaluate cells and other samples such as biological specimens is shown in  FIG. 1 . As shown in  FIG. 1 , electronic device  10  may include optofluidic microscope system-on-chip (SOC)  11 . Optofluidic microscope SOC  11  may include an optofluidic microscope (OFM)  12  for imaging and evaluating samples. Optofluidic microscope SOC  11  (sometimes referred to herein as microscope SOC, OFM-SOC, etc.) may include processing and control circuitry such as circuitry  9  for operations such as operating optofluidic microscope  12 . Circuitry  9  associated with microscope SOC  11  may include circuitry formed on a common integrated circuit die together with the optofluidic microscope (sometimes referred to as a system-on-chip or SOC arrangement). If desired, microscope SOC  11  may include additional circuitry formed on a separate integrated circuit die. Electronic device  10  may, if desired, include storage such as memory  14 . Memory  14  may include volatile memory (e.g., static or dynamic random-access memory), non-volatile memory (e.g., flash memory), etc. Memory  14  may be configured to store image data, processed image data, spectral data, florescence data, sample identifying data, analysis results, etc. resulting from operation of optofluidic microscope SOC  11 . Electronic device  10  may provide a user with the ability to interact electronic device  10 . User interactions may include inputting identifying information (e.g., information identifying a sample, a sample donor, a geographic location, etc.) and obtaining output information (e.g., reading the result of an analysis performed by the optofluidic microscope), etc. To implement these interactions, electronic device  10  may have input-output devices  18  such as keypads, virtual keypads, buttons, displays, or other suitable input-output components. Input-output devices  18  may be associated with one or more output ports such as output port  98  mounted in a housing such as housing  102  of device  10 . 
     An illustrative configuration that may be used for optofluidic microscope SOC  11  is shown in  FIG. 2 . As shown in  FIG. 2 , microscope SOC  11  may include an optofluidic microscope (OFM)  12 , and circuitry  9  that includes control circuitry such as camera control circuitry  13 , OFM control circuitry  15 , fluorescence detection chamber (FDC) control circuitry  17 , wireless communications circuitry  19  and/or general purpose processing circuitry such as processing circuitry  21 . In the system-on-chip or SOC arrangement of microscope SOC  11 , OFM  12 , camera control circuitry  13 , microscope control circuitry (i.e., OFM control circuitry)  15 , channel control circuitry (i.e., FDC control circuitry)  17 , wireless communications circuitry  19  and processing circuitry  21  are implemented on common integrated circuit die  34  (sometimes referred to herein as semiconductor substrate  34 , integrated circuit  34 , integrated circuit substrate  34 , or substrate  34 ). The use of a single integrated circuit such as integrated circuit  34  to implement OFM-SOC  11  can help to minimize costs and reduce the size of electronic device  10  of  FIG. 1 . 
     OFM  12  may include an image sensor (or imager) such as image sensor  302  for imaging samples within OFM  12 . Camera control circuitry  13  of  FIG. 2  may be used to control imaging functions for OFM  12 . OFM  12  may include an array of image pixels such as pixel array  304  and image sensor circuitry such as image sensor circuitry  306 . Image sensor circuitry may row control circuitry, column readout circuitry, analog-to-digital conversion circuitry or other circuitry associated with the capture of raw data using image pixels of imager  302 . 
     OFM  12  may include optofluidic microscope (OFM) structures such as one more channels through which fluid may flow during operation of OFM  12 . Camera control circuitry  13  may be used to direct imager  302  of OFM  12  to image the fluid as it flows through one of the channels of OFM  12 . Camera control circuitry  13  may be configured to control exposure time of an imager associated with OFM-SOC  11 , to perform image correction operations such as white balance and color correction operations, or to otherwise operate imaging functions of OFM-SOC  11 . OFM circuitry  15  may be used to control the flow of fluids in channels of OFM  12 . OFM structures  300  may include fluid control structures (e.g., gates, electrodes, etc.) for controlling the flow of fluids through the channels of OFM  12 . OFM circuitry  15  may be used to operate fluid control structures during analysis of fluid samples. OFM  12  may include one or more florescence detection chambers (FDCs) for collecting and analyzing fluid samples within OFM  12 . FDC control circuitry  17  may be used to operation FDC components such as heaters, electrodes, light sources, etc. that may induce florescence of fluid or other samples within an FDC. 
     OFM-SOC  11  may also include wireless communications circuitry such as wireless communications circuitry  19 . Wireless communications circuitry  19  may be used to transmit wireless data to remote equipment such as a computer, a handheld electronic device, a cellular telephone, a network router, a network antenna, etc. For example, wireless communications circuitry  19  may be configured to transmit or receive data at WiFi® frequencies (e.g., 2.4 GHz and 5 GHz), Bluetooth® frequencies (e.g., 2.4 GHz), cellular telephone frequencies (e.g., 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, and 2100 MHz), or other frequencies. Wireless data transmitted using wireless communications circuitry  19  may include identifying data of a particular OFM-SOC, identifying data of a sample, geographic location data identifying the location of the OFM-SOC, analysis data resulting from analysis of a sample within an OFM-SOC such as OFM-SOC  11 , imaging data obtained using OFM-SOC  11 , etc. 
     OFM-SOC  11  may further include general purpose processing circuitry such as processing circuitry  21  of  FIG. 2 . Processing circuitry  21  of OFM-SOC  11  may be configured to operate a display associated with electronic device  10  (see  FIG. 1 ), perform analysis tasks on data obtained using OFM control circuitry  15 , camera control circuitry  13 , and FDC control circuitry  17 . Processing circuitry  21  may be used for additional processing or compression of images captured using OFM  12 , may be used for spectral analysis of imaging data obtained using OFM  12 , etc. Processing circuitry  21  may be used for temperature control operations. For example, processing circuitry  21  may include temperature control elements such as one or more resistive elements that increase in temperature when a current is applied or other temperature control elements for cooling some or all of OFM  12 . Heating of resistive elements of processing circuitry  21  may help heat microscope SOC  11 , OFM  12 , or individual portions of OFM  12 . 
     As shown in  FIG. 3 , OFM  12  of device  10  may include pixels  36  in one or more channels such as channel  16 . Pixels  36  of channel  16  may form a portion of pixel array  304  of image sensor  302  of  FIG. 2  and may be arranged to form imager  54  in channel  16 . Pixels  36  may be arranged in a diagonal line that extends across the width of channel  16  or may be arranged in other suitable patterns. The use of a diagonal set of image acquisition pixels  36  in channel  16  may help improve resolution (i.e., lateral resolution in dimension y perpendicular to longitudinal axis  52 ) by increasing the number of pixels  36  per unit length in dimension x. The image acquisition pixels  36  in channel  16  (i.e., the imager sensor pixels) are sometimes referred to as forming an image acquisition region, image sensor, or imager. 
     OFM  12  may include a light source configured to be adjusted to produce one or more different colors of light during image acquisition operations. Channels  16  in OFM  12  of device  10  (see  FIG. 1 ) may be provided with one or more imagers  54 . The different colors of light may be used in gathering image data in different color channels. If desired, a different respective light color may be used in illuminating a sample such as sample  22  as sample  22  passes each respective imager within a set of multiple imagers  54  in a given channel by moving in direction  58  with a fluid in the channel. 
     In some situations, it may be desirable to mix sample  22  with a reactant such as reactants  72 . Examples of reactants that may be introduced into channel  16  with sample such as sample  22  include diluents (e.g., fluids such as ionic fluids), dyes (e.g., fluorescent dyes) or other chemical compounds, biological agents such as antigens, antibodies (e.g., antibodies with dye), reagents, phosphors, electrolytes, analyte-specific antibodies, etc. 
     With one suitable arrangement, one or more reactants may be introduced within a portion of channel  16 . The portion of channel  16  that receives the reactant may be, for example, a portion of channel  16  that has been widened or a portion of channel  16  that has the same width as the rest of the channel. Portions of channel  16  (whether widened or having other shapes) that receive reactant or that may be used to introduce sample material into channel  16  are sometimes referred to herein as chambers (or reservoirs, evaluation chambers, fluorescence detection chambers, etc.)  66 . In the example of  FIG. 3 , channel  16  has three associated evaluation chambers  66  containing reactant  72 . Each chamber  66  may contain a different reactant or a reactant in a different concentration from the reactant in another chamber  66 . OFM  12  of  FIG. 3  having a single channel  16  having three associated chambers  66  is merely illustrative. OFM  12  may contain more than one channel  16 . Each channel  16  may contain one chamber  66 , no chambers  66 , two chambers  66 , three chambers  66  or, if desired, more than three chambers  66 . 
     Channels  16  in OFM  12  may be provided with fluid control components such as electrodes or gating structures. As shown in  FIG. 3 , channels  16  in OFM  12  may be provided with configurable gate structures (gating structures) such as gate structures  60  used to selectively block the flow of a fluid containing sample  22 . In the example of  FIG. 3 , OFM  12  contains a gate structure  60  that controls the flow of a fluid containing sample  22  from entrance chamber  68  into channel  16 . Entrance chamber  68  may contain an entrance port  67  through which fluid samples may be introduced into OFM  12 . OFM control circuitry  15  (see  FIG. 2 ) may be configured to operate a gate structure such as gate structure  60  that is interposed between entrance chamber  68  and channel  16  to allow sample  22  to flow into channel  16 . Imager  54  may be used to capture image data of sample  22  as sample  22  flows past image sensor pixels  36  in channel  16 . 
     As shown in  FIG. 3 , OFM  12  may be provided with additional gate structures  60  adjacent to each evaluation chamber  66 . Gate structures  60  associated with chambers  66  may be selectively operated using OFM control circuitry  15  to allow sample  22  to flow into a selected chamber  66 . Gate structures  60  may be opened using OFM control circuitry  15  in such a way that sample  22  first enters one chamber  66  having a first reactant  72  and subsequently enters a different chamber  66  having a different reactant  72 . 
       FIG. 4  shows how gate structures such as gate structure  60  may be operated by OFM control circuitry  15  to control the flow of samples such as sample  22  ( FIG. 3 ) in a fluid  20  through channels  16  of OFM  12 . As shown in  FIG. 4 , gate structure  60  may have open and closed positions. In the example of  FIG. 4 , gate structure  60  in its closed position in which the flow of fluid  20  is blocked. When moved in direction  65  to open position  62 , or when otherwise opened, gate structure  60  permits fluid  20  to flow through channel  16 . Gate structures such as gate structure  60  may, for example, be formed from MEMs structures, electrode-based structures, or other structures that can selectively permit fluid to flow or block fluid from flowing. Electrodes or other fluid control mechanisms (e.g., MEMs structures, external pumps, etc.) associated with optofluidic microscope  12  may be used to cause the sample fluid to flow through channel  16 . Gate structures such as gate structure  60  may be used to selectively block the flow of the sample. For example, gate structure  60  may be placed in a closed position to momentarily prevent fluid from flowing and thereby ensure that the fluid remains in contact with a reactant for an amount of time that is appropriate for that reactant to interact with the sample. Once the appropriate amount of time has elapsed, control circuitry such as OFM circuitry  15  or FDC circuitry  17  (see  FIG. 2 ) may open gate structure  60  to allow the fluid sample to proceed past one or more imagers  54  or to flow into one or more chambers such as chambers  66  of  FIG. 3 . 
     A cross-sectional side view of an illustrative image sensor pixel  36  is shown in  FIG. 5 . As shown in  FIG. 5 , image sensor pixels  36  on integrated circuit  34  may each include a corresponding photosensitive element such as photodiode  44 . Complementary metal-oxide-semiconductor (CMOS) technology or other image sensor integrated circuit technologies may be used in forming image sensor pixels  36  and integrated circuit  34 . Light guides such as light guide  46  may be used to concentrate incoming image light  50  into respective photodiodes  44 . Photodiodes  44  may each convert incoming light into corresponding electrical charge. Image sensor circuitry  48 , may be used to convert the charge from photodiodes  44  into analog and/or digital image data. In a typical arrangement, data is acquired in frames. Camera control circuitry  13  may convert raw digital data captured using image sensor circuitry  48  from one or more acquired image data frames into images of samples  22 . Camera control circuitry  13  may perform other high level processing on images of samples  22  (e.g., white balance corrections, color corrections, etc.). 
     A cross-sectional side view of an illustrative optofluidic microscope having a chamber that has been provided with reactant is shown in  FIG. 6 . In electronic device  10  of  FIG. 4 , a fluid sample can be introduced into channel  16  on integrated circuit substrate  34  through entrance port  24  in glass layer  28 . The fluid and associated particles within the fluid such as sample  22  may flow through channel  16  as illustrated by fluid flow arrow  20 . Imager  54  may be used to gather images of sample  22  as sample  22  passes over imager  54 . 
     Part of channel  16  may be used to form chamber  66 . Chamber  66  may be provided with reactant such as reactant  72  and/or components for evaluating samples such as cell  22 . As shown in  FIG. 6 , for example, reactant  72  such as a fluorescent dye or other reactant may be used to cover the lower surface and/or upper surface of chamber  66 . Chamber  66  may therefore be a fluorescence detection chamber (FDC) configured to detect fluorescence by sample  22  using FDC control circuitry  17  on integrated circuit  34 . The lower surface of chamber  66  (i.e., the lower surface of channel  16 ) may have a pattern of image sensor pixels  36  that form one or more light sensors (e.g., one or more light meters) such as light sensor  61 . Light sensor  61  may be formed from a portion of pixel array  304  of  FIG. 2 . The image pixels that make up light sensor  61  may be used collectively (i.e., in a binned fashion) to improve noise performance and/or may be used individually (or in small groups associated with respective light sensors) to gather location-dependent light readings. FDC control circuitry  17  or camera control circuitry  13  of  FIG. 2  may be configured to selectively use pixels  36  collectively or individually. Reactant  72  may be formed on or near the image sensor pixels  36  in chamber  66  and/or on the upper surface of channel  16  (as examples). When fluid and samples  22  reach chamber  66 , reactant  72  may react with the fluid and/or cells. For example, dye in layers  72  may dye the cells. 
     In the illustrative configuration of  FIG. 6 , upper portion  64  of chamber  16  has been provided with elements  64 - 1 ,  64 - 2 , . . .  64 -N. Elements  64 - 1 ,  64 - 2 , . . .  64 -N may be transparent colored filter elements that are arranged in a tiled fashion over the upper surface of chamber  66 . Each filter element may be used to filter light entering and/or exiting chamber  66 . For example, each filter element may be used to filter a white light illumination source, thereby illuminating the interior of chamber  66  with various different types of colored light. The sample within chamber  66  (e.g., the fluid containing dyed cells or other sample particles) may respond differently to different colors of light. For example, the sample may fluoresce in response to illumination with one color of light but not in response to another. The use of different colors of light to illuminate different portions of the sample with different wavelengths of interest can therefore be useful in analyzing the sample. Filter elements  37 - 1 ,  37 - 2 , . . .  37 -N may also be used to filter light emissions from within chamber  66 . Lower portion  37  of chamber  66  has been provided with elements  37 - 1 ,  37 - 2 , . . .  37 -N. Elements  37 - 1 ,  37 - 2 , . . .  37 -N may be transparent colored filter elements that are arranged in a tiled fashion over the upper surface of chamber  66 . Each filter element may be used to filter light entering light sensor  61 . For example, each filter element may be used to filter a white light illumination source, thereby illuminating the portions of light sensor  61  with various different types of colored light. The collection of different colors of light using light sensor  61  can therefore be useful in analyzing the sample. Reactant  72  may be provided in a uniform coating over a sidewall, over a lower chamber surface, over an upper chamber surface, or in other suitable chamber regions. If desired, reactant  72  may be patterned. For example, some regions of a chamber may be coated with reactant and other regions of the chamber may be left uncoated. Different reactants may be provided in different regions (e.g., in a tiled pattern on the lower or upper surface of the chamber, etc.). Any suitable number of different reactants may be used within one chamber (e.g., one, two, three, four, more than four, etc.). Channel  16  may be provided with gate structures such as gate structure  60  for controlling the flow of fluid  20  into chamber  66 . 
       FIGS. 7 ,  8 , and  9  are cross-sectional end views of illustrative types of chambers that may be used in implementing chambers in OFM  12  of OFM-SOC  11  of device  10 . As shown in  FIG. 7 , entrance chamber  68  may contain an entrance port. Samples may be introduced into chamber  68  for distribution to an array of channels  16 . Structures such as standoffs  40  (e.g., polymer standoffs) may be used to elevate the lower surface of glass layer  28  from the upper surface of integrated circuit  34 . This forms one or more channels  16 . Channels  16  may have lateral dimensions (dimensions parallel to dimensions x and z in the example of  FIG. 3 ) of a millimeter or less (as an example). The length of each channel (the dimension of channel  16  along dimension y in the example of  FIG. 3 ) may be 1-10 mm, less than 10 mm, more than 10 mm, or other suitable length. Standoff structures  40  may be patterned to form sidewalls for channels such as channel  16 . 
       FIG. 8  shows how evaluation chamber  66  may be provided with a temperature control element such as heater  74 . Heater  74  may be, for example, a resistive heater that is controlled by FDC control circuitry  17  or processing circuitry  21  ( FIG. 2 ). During sample evaluation operations, heater  74  may be turned on and off to cycle the temperature in the interior of the chamber. Voltages may be applied to chambers such as chamber  66  of  FIG. 8  using electrodes such as electrode  38 . By controlling the voltages on electrodes  38  in chambers  66  and/or other channel structures in OFM  12  using FDC control circuitry  17 , the flow of sample fluids such as ionic fluids may be controlled. 
     As shown in the example of  FIG. 9 , chamber  66  may be provided with a light source such as light source  76  that produces light  78  of one or more different colors (using optional color filters in light source  76  and/or light filters integrated into the upper surface of chamber  66  in a pattern of the type shown in  FIG. 9 ). Reactant  72  may be provided on any of the exposed surfaces of chamber  66 . In the  FIG. 8  example, reactant  72  has been provided on a lower chamber surface (as an example). Image sensor pixels  36  may be used to form one or more image sensors  61 . Image sensor pixels  36  of image sensors  61  may be configured to receive light of various colors (using optional color filters over image sensor pixels  36  or integrated into the lower surface of chamber  66 ). 
     OFM  12  of OFM-SOC  11  of device  10  may include one or more channels  16  and one or more chambers  66  associated with each channel.  FIG. 10  is an illustrative example of another embodiment of an OFM of the type that may be included in OFM-SOC  11  of  FIG. 2  having multiple channels  16 . In the example of  FIG. 10 , integrated circuit substrate (substrate  34 ) that has multiple channels  16 . Channels  16  may, in general, be arranged on the surface of substrate  34  in a pattern with parallel channel segments (as shown in  FIG. 10 ), in a pattern with perpendicular channel segments, in a pattern in which channels branch from one another at non-parallel and non-perpendicular angles, or other suitable channel patterns. The arrangement of  FIG. 10  is merely illustrative. Sample reservoir  68  may have exit ports coupled to each of the channels. In the example of  FIG. 10 , there are six parallel channels  16 , so there are six corresponding exit ports that couple sample reservoir  68  to channels  16 . In systems with different numbers of channels (e.g., more than six channels or fewer than six channels), different corresponding numbers of exit ports may be formed in sample reservoir  68 . 
     Fluid samples may be introduced into sample reservoir  68  through entrance port  67  (e.g., a hole in a cover such as hole  24  in cover layer  28  of  FIG. 6 ). By introducing fluid into reservoir  68  through entrance port  67 , a fluid sample may be distributed among the channels. 
     It may be desirable to introduce reactant into channels  16 . For example, reactants may be used to make cells and other particles more visible within channels  16  (e.g., by staining the cells with dye, etc.). As shown in  FIG. 10 , reactant  72  may be supplied  10  to each channel  16  using a corresponding reactant chamber  70 . There may be one or more different reactants in each reactant chamber  70 . 
     OFM control circuitry such as OFM control circuitry  15  of  FIG. 2  may be configured to operate gate structures  60  in order to control the amount of time that the sample spends in each reactant chamber  70 . In some situations (e.g., when a reactant is slow-acting or when a longer reactant exposure time is desired), it may be desirable to hold the sample in a particular reactant chamber for a relatively long period of time. In other situations (e.g., when a reactant is fast acting or when a shorter reactant exposure time is desired), it may be desirable to hold the sample in a reactant chamber for a relatively short period of time. Using gate structures  60  of  FIG. 10 , some portions of a sample may be exposed to reactant  72  for longer than others portions of the sample. Different reactants may also be placed in different respective chambers  70 . 
     Consider, as an example, a situation in which a particular type of cell is to be imaged following staining of the cell with a dye. The appearance of the stained cell may be different depending on how long the cell is exposed to the reactant. It may therefore be desirable to expose some portions of the sample to the reactant for short periods of time, while exposing other portions of the same sample to the reactant for longer periods of time. The cell may also respond differently to different concentrations of the reactant and different types of reactants. Using reservoir  68 , a sample may be distributed to each of the reactant chambers  70  in OFM  12 . Reactant chambers  70  may hold one or more types of reactant  72  in one or more different concentrations. Gate structures  60  may be used to hold the sample in different reactant chambers for different amounts of time (i.e., different sample hold times). 
     Once the sample has been held in a reactant chamber for a sufficiently long period of time, the gate structure that is associated with that reactant chamber may be opened to release the sample into an adjoining channel. Upon release, the sample in each channel will flow past the imager  54  (or imagers) in that channel. Camera control circuitry such as camera control circuitry  13  of  FIG. 2  may be used to operate imagers  54  in gathering image data for the sample. The image data may be processed using camera control circuitry  13  to form images of the sample. The images that are formed may be displayed for a user on a display, may be stored in memory such as memory  14  of  FIG. 1  or further processed or analyzed using processing circuitry  21  of  FIG. 2 . Because each imager  54  can gather image data from a sample that has been exposed to reactant in a different way (e.g., a different reactant type, different exposure time, different reactant concentration, etc.), each imager  54  can gather a different type of image data. During image processing operations using camera control circuitry  13  and processing circuitry  21 , the image data may be processed to form images of cells and other particles in the sample. 
     As shown in  FIG. 10 , after a portion of the sample passes by each imager  54 , that portion of the sample may flow into a corresponding FDC chamber  66 . FDC chambers  66  may be spent sample reservoirs or may contain components for evaluating the sample. For example, chambers  66  may include components that are controlled by camera control circuitry  13  or FDC control circuitry  17  of  FIG. 2  and that are been configured to serve as light sensors, light sources for illuminating the sample (e.g., for fluorescence measurements), heaters for heating the samples, additional reactant, etc. 
       FIG. 11  is a graph showing how the control signals (i.e., signals generated using control circuitry  15  of  FIG. 2 ) that are applied to each gate structure  60  in  FIG. 10  may potentially be different. Each trace in the example of  FIG. 11  corresponds to an illustrative control signal for a different respective one of the six gate structures  60  in  FIG. 10 . In this example, the status of the gate structures is controlled by the state of the control signal generated by OFM control circuitry  15 . When the control signal for a given gate structure is deasserted (e.g., when the control signal is taken low), the gate structure is held in its closed state. When the control signal for a given gate structure is asserted (e.g., when the control signal is taken high using OFM control circuitry  15 ), the gate structure is placed in its open state. As shown in  FIG. 11 , at time t 0 , a first of the gate structures  60  (i.e., the uppermost gate structure  60  in  FIG. 10 ) may be opened, whereas the remaining gate structures  60  remain closed. At time t 1 , a second of the gate structures  60  is opened by asserting control signal  78 . The four remaining gate structures are likewise moved from their closed to open states at times t 2 , t 3 , t 4 , t 5 , and t 6 , respectively, as illustrated by control signals  80 ,  82 ,  84 ,  86 , and  88 . Using this type of arrangement, the portion of the fluid sample that is contained in the first reactant chamber (i.e., the sample in the uppermost reactant chamber in the example of 10  FIG. 10 ) is exposed to a first reactant in a first concentration for a first period of time (i.e., time t 0 , assuming that the fluid is placed in the reactant chambers at time t=0). The portion of the fluid sample that is placed in the other reactant chambers is exposed to reactant for different exposure times (i.e., sample hold times t 1 , t 2 , t 3 , t 4 , t 5 , and t 6 ). Each reactant chamber potentially has a different type of reactant and a different reactant concentration. The use of potentially different respective hold times for the sample in each reactant chamber allows the hold times for holding the sample in the reactant chambers to be individualized to the type and concentration of reactant in each reactant chamber and other factors. 
       FIG. 12  is a perspective view showing how an electronic device  10  may be configured to communicate with data analysis equipment  104 . Data analysis equipment  104  may be based on one or more computers or other computing equipment. Equipment  104  may, for example, include computing equipment such as computing equipment  92 . An associated display such as display  94  may be used in presenting visual information to a user such as images of cells and other samples  25  acquired using device  10 . User input interface  96  may be used to gather input from a user and to supply output for a user. For example, user input interface  96  may contain user input devices such as keyboards, keypads, mice, trackballs, track pads, etc. User input interface  96  may also include equipment for supplying output such as speakers for providing audio output, status indicator lights for providing visible output, etc. 
     Equipment  104  may include a data port such as data port  90 . Data port  90  may be, for example, a Universal Serial Bus (USB) port. As shown in  FIG. 1 , device  10  may have an output port such as connector  98  (e.g., a USB connector) that is configured to mate with the connector in port  90 . Connector  98  may be mounted in a housing  102  of device  10 . Device  10  may include a fluid sample entrance port such as port  66 . Port  66  may be aligned with port  66  of  FIG. 2  or  10 , so that samples that are placed in port  66  of device  10  flow into sample reservoir  68  of microscope  12  within housing  102 . After a sample has been introduced into device  10  through port  67 , camera control circuitry  13  on integrated circuit die  34  ( FIG. 1 ) may be used to gather image data for forming one or more sample images. 
     After sample processing is complete, the user may insert device  10  into port  90 , so that the data from device  10  may be passed to equipment  104  using general purpose processing circuitry  21  ( FIG. 2 ) and further analyzed (e.g., to produce images of the sample from raw image data, to produce enhanced images, etc.). 
     Alternatively, device  10  may be connected to computing equipment  92  via a wired connection such as wired connection  103 . Computing equipment  92  may be a portable electronic device (e.g., a mobile phone, a personal digital assistant, laptop computer, or other computing equipment). Computing equipment  92  may be used to process data from device  10 . Computing equipment  92  may be used to transmit data from device  10  to computing and data processing equipment  93  along communications path  95 . Communications path  95  may be a wired or wireless connection. Communications path  95  may be used to directly transfer data from device  10  to computing and data analysis equipment  93  using wireless communications circuitry formed on a common integrated circuit die with an OFM in device  10  such as wireless communications circuitry  19  of  FIG. 2 . Alternatively, communications path  95  may be used to transfer data from device  10  to computing and data analysis equipment  93  over a wired network. Computing and data processing equipment  93  may be a remote mainframe computer, may be a cloud computing network (i.e. a network of computers on which software can be run from computing equipment  92 ) or other computing equipment. 
     Wireless communications circuitry  19  in device  10  may be configured to transfer data over wireless communication path  97  to antenna  99 . Antenna  99  may relay data communicated wirelessly from device  10  to a network  101  and to computing and data processing equipment  93 . Equipment such as device  10  having an OFM-SOC such as OFM-SOC  11  (see, e.g.,  FIG. 2 ) may be produced inexpensively in volume and may be disposed of after a single use (as an example). 
     Illustrative steps involved in using an electronic device having an optofluidic microscope system-on-chip to gather and analyze data on a sample are shown in  FIG. 13 . 
     At step  200 , a user of the device may place a sample in sample reservoir  68  ( FIG. 3 ) through sample entrance port  67  ( FIGS. 3 and 10 ). Once the sample flows into reservoir  68  and, if desired, associated reactant chambers  70 , the sample will interact with the reactant. 
     At step  201 , wireless communications circuitry  19  ( FIG. 2 ) may be used to exchange (i.e., transmit and receive) data with a host system such as data analysis equipment  104  of  FIG. 12 . Data exchanged with data analysis equipment  104  may in clued control data for controlling OFM  12 , setup data for configuring OFM  12  for testing or other data. If desired, wireless communications circuitry  19  may be used to exchange data with data analysis equipment  104  before introducing a sample into sample reservoir  68  as described in connection with step  200 . 
     Different reactant chambers may require different amounts of sample hold time. Accordingly, OFM control circuitry  15  ( FIG. 2 ) may selectively activate gate structures  60  during the operations of step  202 . OFM control circuitry  15  may, for example, open gate structures  60  in different channels at different times, as described in connection with the gate control signals of  FIG. 4 . This causes the sample fluid from each reactant chamber to flow over a corresponding imager after being held for a different respective sample hold time. 
     At step  204 , as the sample fluid flows over imagers  54 , camera control circuitry  13  ( FIG. 2 ) may operate imagers  54  to acquire image data for the cells or other samples in the fluid. 
     At step  206 , image processing operations may be performed by processing circuitry  21  ( FIG. 2 ) of device  10 . During image processing operations, processing circuitry  21  may extract information from processed image data in order to determine an appropriate FDC chamber  66  for further analysis of the sample. 
     At step  208 , OFM control circuitry  15  may selectively activate gate structures  60  associated with FDCs for further analysis of the sample. 
     At step  210 , FDC control circuitry  17  ( FIG. 2 ) may be used to operate image pixels, heaters, electrodes, light sources or other components of fluorescence detection chambers  66  during analysis of the sample. 
     At step  212 , image processing operations may be performed using processing circuitry  21  on fluorescence image data captured in FDCs  66 . Fluorescence image data may be analyzed using processing circuitry  21  to determine a test result from the fluorescence image data. As an example, a sample containing viral cells may fluoresce differently than a sample without viral cells. Processing circuitry  21  may be configured to determine the presence (or lack thereof) of viral cells in the sample based on the fluorescence image data. 
     At step  214 , if desired, processing circuitry  21  may be used to operate a display associated with input-output devices  18  ( FIG. 1 ) to display a test result (e.g., positive or negative viral test results) to a user of device  10 . 
     Test results, image data, fluorescence image data or other data may be stored in memory  14  of device  10 . 
     At step  216 , wireless communications circuitry formed on integrated circuit die  34  ( FIG. 2 ) may be used to transmit some or a portion of image data, fluorescence image data, test results (e.g., spectral analysis results, cell counting results, etc.) or other data to computing and data analysis equipment such as computing and data analysis equipment  93  of  FIG. 12 . 
     Various embodiments have been described illustrating an electronic device for imaging and evaluating samples of fluids containing cells and other materials. An integrated circuit may be provided with fluid channels and control circuitry. Sets of image sensor pixels from an image sensor array on the integrated circuit may form imagers in the fluid channels. Control circuitry on the integrated circuit may be configured to operate the image sensor pixels. The fluid channels and image sensor pixels may form a portion of an optofluidic microscope formed on the integrated circuit. The optofluidic microscope may include one or more reactant chambers, evaluation chambers or fluorescence detection chambers associated with each fluid channel. Control circuitry on the integrated circuit may be configured to operate gate structures within the channels to control fluid flow through the fluid channels. Control circuitry on the integrated circuit may be configured to operate gate structures adjacent to the evaluation chambers to control fluid flow from the fluid channels into the evaluation chambers. 
     A sample may be introduced into a channel for imaging by the imagers and for evaluation using other sample evaluation structures. The channels on the integrated circuit may have multiple branches. Flow control structures such as electrodes and gate structures such as microelectromechanical systems (MEMS) gate structures may be used to route fluid through various branches in the channel. For example, flow control structures may be used to route a sample to one or more different chambers for evaluation. Chambers in the channel may include reactant for reacting with the sample, a light source for providing illumination for the sample, a heater for heating the sample, and image sensor pixels. Chamber control circuitry on the integrated circuit may be configured to operate operable components such as the light source, the heater, and, if desired, the image sensor pixels. The image sensor pixels may be used in forming one or more light sensors in each chamber. Camera control circuitry on the integrated circuit may be configured to operate image pixels in the fluid channels for imaging of the samples. Camera control circuitry may be further configured to perform processing operations such as white balance and color correction of captured image data. 
     The optofluidic microscope SOC may include wireless communications circuitry on the integrated circuit die for wireless communicating data to remote computing equipment. The optofluidic microscope SOC may include general purpose processing circuitry on the integrated circuit die for image processing, temperature control or other operations of the OFM-SOC. 
     The foregoing is merely illustrative of the principles of this invention which can be practiced in other embodiments.