## 4 Conclusions  
This work describes the evaluation of a Rapid Stain Identification Reader System. The Reader System is a ruggedized strip test reader unit that allows analysis and documentation of RSIDTM lateral flow strip tests using pre-configured settings. The unit features a touch screen based on Palm Pilot technology and a charge-coupled device (CCD) imaging system for analyzing RSIDTM cassettes. The test data, including reader ID, test name, sample ID, date and time of the test, results of the analysis and digital images of control and test lines of RSIDTM strips are automatically recorded by and stored in the RSIDTM Reader memory; these data can be downloaded through a USB cable to a computer and are then displayed in the format shown (Figure 1B). In this study we tested the RSIDTM Reader with RSIDTM Blood, Saliva, Semen and Urine Kits and RSIDTM Field Kits for blood, saliva, semen and urine (Independent Forensics, Lombard, IL, USA). Although scoring these tests does not require electronic image analysis or an optical reader, there are administrative and legal pressures to create and maintain an electronic record of the identification of body fluids from forensic evidence. Additionally, an impartial scoring of the tests by a calibrated instrument may be useful in resolving potentially ambiguous results obtained from a sample with very small amount of biological material that will produce very faint bands at the Test line. This latter point is supported by the accurate and reproducible performance of the RSIDTM Reader when testing volumes of blood, saliva, semen and urine that are at the respective detection thresholds. The RSIDTM Reader accurately and reproducibly detected very weak bands generated by very small volumes of body fluids, --estimated 50 nL of blood (Figure 2, Cassettes 3 and 4), 10 nL of saliva (Figure 3, Cassettes 3 and 4), 2.5 nL of semen (Figure 4, Cassettes 3 and 4), and 1 \(\mu\)L of urine (Figure 5, Cassettes 3 and 4). It must be noted that faint bands produced by a high dose hook effect (arguably at  
Figure 6: Results of RSIDTM Reader analysis using Field Kit Protocol. **Top—**Digital image of cassettes (C—Control; T—Test) with analyzed volumes indicated. **Bottom—**Images taken from RSIDTM Reader. Results as scored by RSIDTM Reader are shown (positive [+] or negative [-]). The RSIDTM-Semen test with 5.3 \(\mu\)L of semen demonstrates a high dose hook effect, however a positive result was still scored by the RSIDTM Reader. Note: Camera capture or RSIDTM Reader images are slightly _less_ sensitive than visual observation of the cassettes. the other end of the detection threshold) were also scored accurately by the Reader (field kit protocol, 5.3 \(\upmu\)L of semen, Figure. 6). The accuracy and reproducibility of the Reader system was achieved through extensive calibration testing using six RSID(tm) Readers and more than 800 samples of RSID(tm) Blood, Saliva, Semen and Urine tests from our extensive collection of retained lots of RSID(tm) tests. This background work was performed in our laboratory as part of the developmental validation of the RSID(tm) Reader System. Using this foundation, we have configured the Reader to be accurate, reproducible and an effective, if not required, tool for the identification of body fluids from forensic evidence. Lateral flow strip tests are in general qualitative; only yes/no, positive/negative results can be assessed from the running of these tests. There is the formal possibility of using lateral flow tests for quantitative measurements; given the many unavoidable uncertainties involved in forensic crime analysis including trying to estimate the size of the original stain, the efficiency of extraction, the possibility of degradation over time, the effects of long-term storage, the stability of the bio-marker used by the test, converting these tests for quantitative analysis would offer little benefit to criminal investigators.